Measurement of the color of the target in the area of ​​interest and N color measurement targets under controlled lighting

Abstract

A mobile phone accessory (1) associated with a smartphone, comprising: a support and handling housing having an interior space (11a), an inner face (13a), a hole (16) to be associated with an AOI target and located within a light entrance point (15), and a rear wall portion (14b); an illumination member (22) having an axis (22a) and for generating light for illuminating said point (15); a camera field of view (19) having an axis (19a) and for taking a reflected photograph of said point (15) and its contents; a diffuser plate (27) having a diffuser opening (30) with a center (19aa) and a center (22aa) and comprising a high-opacity portion and a low-opacity portion, said mobile phone accessory containing N color measurement targets The target is fixed on a surface (13a) of a front wall portion (14a) with the measuring hole (16) on the side, and the point (15) is seen through the scattering opening (30). The scattering plate (27) has a varying opacity, wherein a portion (25) or a region (32a) on and around the center (22aa) has a high opacity, and a portion (26) or a region (26b) opposite and near the scattering opening (30) has a low opacity, and the opacity decreases continuously from the portion or region with high opacity to the portion or region with low opacity. The scattering plate (27) also makes the illumination uniform within the range of the AOI target and the range of the N color measurement targets (17).

Description

[0001] The field of the present invention is to measure the color of an area of ​​interest of an original, unaltered material from the outside, based on a comparison of the color of the area of ​​interest with a color of N appropriately known and selected colors of a color measurement target taken from the same photograph, obtained by reflection under identical controlled and known lighting conditions (i.e., light uniformly distributed over the area of ​​the area of ​​interest and the color measurement target). The color measurement of the area of ​​interest can be performed by the user themselves, typically at home, using a smartphone accessory that is adapted and intended to be functionally and structurally associated with a smartphone that has downloaded an application for measuring the color of the target. However, the field of the present invention does not exclude professional use.

[0002] The term "area of ​​interest" (most commonly abbreviated as AOI) must be included as a limited, selected surface area of ​​the original, unaltered material, not a portion extracted from the material. The AOI target is provided without destroying or requiring damage to the material, preserving its original shape. Therefore, the color measurement of the AOI target is non-destructive.

[0003] Such an AOI target may be an area of ​​human skin (skin target).

[0004] The requirements and constraints described above help define the scope of the present invention. AOI targets are typically areas of human skin (skin targets). However, there are other applications with similar requirements and constraints, such as measuring the color of fashion accessories, decorative finishes, textiles, painted walls, other cosmetics, and even the skin of animals or plants. Nevertheless, the following description is made with reference to skin targets, and the scope of the present invention encompasses other targets with similar characteristics.

[0005] More specifically, measuring a person's skin color is done for cosmetic, healthcare, medical, or practical purposes. For example, a person might want to choose a product—makeup like lipstick or face powder—or clothing that matches their skin color. Alternatively, a person might want to monitor their tan after prolonged sun exposure. The term "skin" must be understood to include hair and, more generally, any part of the human body.

[0006] US824374 describes a diagrammatic system in which all the colors found in pigments and their shades, various intensities and brightnesses are shown in a convenient logical order and represented by symbols, and the hues of newly discovered pigments and their brightnesses and intensities can be added and shown on this system in the same order or sequence without disturbing the pre-existing structure.

[0007] US4523852 describes an improved method and apparatus for visually comparing the results of colorimetric test methods with color reference standards, thereby improving the quantification of such tests.

[0008] Color charts, reference cards, or calibration cards are used to compare several colors. These are flat plates that contain several colored reference objects, called "calibration targets," on one side, for example in the form of squares arranged side by side in rows and columns (24 squares in the so-called MacWhite chart). They are used to check the color reproduction of imaging systems or to calibrate cameras (US9749502).

[0009] US2019 / 0279400 describes a color reference chart for comparing an unknown color sample to a set of known color values, the set of known color values ​​comprising a plurality of discrete color reference elements or reflectance samples divided into four quadrants around a central portion, the central portion being a hole or transparent window that enables a portion of the color sample to be observed when the color reference chart is placed between an image capture device and the color sample.

[0010] Based on the fact that scene images captured by multiple cameras have different color values ​​due to different color rendering of different devices, J. Marguier and Al published in The article "Assessing Human Skin Color from Uncalibrated Images," published in the 2007 Wiley journal, Volume 17, pages 143-151, proposes a method for accurately retrieving color information from uncalibrated images captured under uncontrolled lighting conditions, using an unknown device and without access to the original data, but with a limited number of reference colors in the scene. This method is used to assess skin color. The subject is imaged with a calibration target in the scene. This target is extracted, and its color values ​​are used to calculate a color correction transform applied to the entire image. The best mapping is achieved using a target composed of skin color patches representing the entire range of human skin tones. The color information extracted from the image correlates well with color data from spectral measurements of the skin.

[0011] As is well known, mobile devices or portable digital devices that can run programmed applications adapted to perform specific functions, such as smartphones and tablets (the term "smartphone" must be understood in its general meaning; simply put, all such mobile devices or portable digital devices are referred to by the term "smartphone") and include a display, several buttons or numeric keys or a touchpad, a camera, a flashlight, memory for data storage, and one or more downloaded applications (such applications are simply referred to as "apps") have penetrated almost all aspects of life, including monitoring and tracking the current conditions (health, personal care) of smartphone users, gaming, measurement, social network mapping, and health. Using a smartphone camera requires calibration to ensure that the colors captured are true to life. This can be done using the principle of a color calibration target.

[0012] It is well known that in visual observation or observation through optical devices, as well as in photography, video, and film, the lighting of the object being observed or filmed is of paramount importance. There are several types of lighting for the object to be filmed, for example, generally speaking, soft lighting and hard lighting on the one hand, and front lighting, 45° lighting, side lighting, bottom lighting, and so on on the other hand. There are also various methods of controlling light to manipulate how it interacts with the object to be filmed, and there are also various devices that can achieve this, including reflectors, light diffusers, opaque or translucent screens, filters, and other optical devices (US4853744).

[0013] What has just been revealed is part of the common knowledge of those in the field.

[0014] The present invention is based on the principle of measuring the color of an AOI target (e.g., more specifically, a skin target) using N selected color measurement targets, and also for the goal and purpose of achieving this measurement quickly, easily, cheaply, accurately, automatically, and possibly by the user himself, usually at home, using a smartphone accessory, the present invention is suitable and intended to be functionally and structurally associated with a smartphone.

[0015] US2018 / 0143076 describes a device for measuring the color of a substrate, which can be The device interfaces with a smartphone and converts color readings into any number of current color models or spaces. The device comprises a lower housing and an upper housing that cooperate with each other, and a detector portion comprising a printed circuit board attached to the interior of the lower housing. The printed circuit board contains an LED and a color sensor mounted on the underside of the printed circuit board. The device also includes a transparent light pipe and a transparent lens mounted between the underside of the printed circuit board and the interior of the lower housing. Light transmitted by the LED impinges on the substrate and is at least partially reflected back to the color sensor for measurement. However, this device is expensive and unsuitable for personal use.

[0016] US 2017 / 085761, US 9906697, and US 10139712 describe a device for taking close-up photos of the skin to examine its condition, or a device serving as a portable microscope. The device comprises a smartphone equipped with a camera and an LED, and a smartphone accessory (referred to as an external optical module) that is mounted on the smartphone and used to take close-up photos. The smartphone accessory comprises a macro lens, a light guide, and a housing with a hole. The light guide, formed of a transparent material, receives light emitted from the LED and emits the light along the optical axis through an emitting surface disposed on the periphery of the macro lens, illuminating a target in front of the hole. However, the target is not necessarily in contact with the hole. The light guide comprises a light incident portion, a light emitting portion, and a reflective plate to prevent light within the light guide from leaking out. The light emitting portion is disposed on the periphery of the macro lens and is in the form of a transparent flat plate. The light transmitted from the light incident portion is emitted through an emitting surface formed on its upper surface. The reflective plate is formed on the outer surface of the light guide. Light emitted from the LED and entering through the incident surface is transmitted to the light emitting portion and then emitted to the target. The light guide can be either completely opaque or completely transparent. This device does not include or work with a color target and cannot capture color. Furthermore, the emitting surface does not produce a constant illumination on the target surface, which is crucial for proper color measurement processing of photographs, as described in the article "Assessing Human Skin Color from Uncalibrated Images" by J. Marguier and Al. Therefore, this device is neither intended nor suitable for, nor capable of, measuring the color of AOI targets, and its light guide is not suitable for smartphone accessories. Instead, it is intended and intended to be associated with a smartphone to measure the color of AOI targets.

[0017] WO2007111353 relates to a light diffuser characterized by comprising a light diffusing portion formed of foam produced by applying radiant energy and thermal energy, the light diffusing portion having a predetermined cell density distribution pattern. Such a diffusing portion may include different regions.

[0018] US Pat. No. 5,963,333 describes a handheld device for collecting reflectance, density, spectrophotometry, colorimetry, luminescence, or radiometric readings from a sample surface, comprising: a housing having a substantially flat bottom surface and a top surface contoured to fit a human finger or palm; a sensor mounted to the housing, the sensor including a focusing aperture and containing circuitry and optics for performing a reflectance, density, spectrophotometry, or colorimetric reading from a portion of the sample surface aligned with the focusing aperture; a switch operatively coupled to the sensor for activating the sensor to perform a reading; and a data link operatively coupled between the sensor and a computer for relaying data from the sensor to the computer. The sensor comprises: a printed circuit board mounted within the housing; a plurality of light sources mounted within the housing, each emitting light in a significantly different wavelength band; a sample light detector mounted to the printed circuit board; a first optical element for directing a first portion of light emitted by each light source toward the sample surface; and a second optical element for directing a portion of light reflected from the sample toward the sample light detector. The reflective cone has a conical reflective surface tilted 22.5°, so that light from the LED is reflected and strikes the target at a 45° angle. This device has the same disadvantages as described above.

[0019] US2002 / 0036778 describes a handheld, portable color measurement device for measuring three different colors in a color target, comprising: a color measurement probe housing; a hollow probe head attached to one end of the probe housing, the probe head being adapted to be placed next to the color target to be measured; a white light source mounted inside the probe housing and connected to a power source; a color measurement switch mounted on the probe housing, connected to the power source and to the white light source, the white light source illuminating the color target surrounded by the end of the probe head when the measurement switch is actuated; means for capturing a reflected light signal of the color target when the color target is illuminated, disposed inside the probe housing; a three-color sensor mounted inside the probe housing, receiving the reflected light signal from the capturing means; a microprocessor mounted in the probe housing and connected to the power source and the three-color sensor, the microprocessor for processing the reflected light signal; and a display means connected to the microprocessor for displaying the reflected light signal as a percentage of red, green, and blue. Measurement of skin color is not contemplated, and the device is neither lightweight nor inexpensive.

[0020] WO2012 / 058641 describes an optical device that releasably attaches to a smartphone to image the skin surface and body cavities. The device includes optical enhancement elements such as a magnifying lens, an illumination redirecting element, and a filter. A lens slider is provided to allow one or more lenses to be moved along the optical axis. The images can be viewed and analyzed on the mobile device, or transmitted to another location / device for analysis by an individual or software. The results can be used to provide a diagnosis, or for a variety of other applications, including image comparison over time and product recommendations. The device may include a scope for a body cavity or a cylindrical tube for a non-body cavity portion of the skin. It may include an optical fiber, a diffuser, and a calibration module. However, this optical device is neither suitable for nor intended for use by the user to measure the color of the skin themselves.

[0021] WO2004 / 081653 describes a magnifying shooting unit that allows the camera of a camera-equipped mobile phone to capture magnified images using illumination light. The magnifying shooting unit is for use attached to a camera-equipped mobile phone having a lens, an imaging element, and illumination, and includes a magnifying glass, a first reflector, and a second reflector, the second reflector being housed in a main body having a contact portion on its front surface and a first aperture, a second aperture, and a second component on its rear surface, the second component being used to detachably attach the unit to the camera-equipped mobile phone. When the magnifying shooting unit is attached to the camera-equipped mobile phone, the magnifying glass is located in front of the mobile phone lens to allow magnified image capture. In addition, illumination light from the mobile phone illumination is reflected from the second reflector and the first reflector in sequence and directed to the subject, thereby illuminating it.

[0022] US2014 / 0285806 relates to methods and components for calibrating and matching color and light. Some embodiments also incorporate additional functionality, including but not limited to communication, sensing, display, and data processing elements. Various embodiments may be performed and / or implemented using hardware, software, one or more entities, and / or some combination of hardware, software, and / or one or more entities.

[0023] DE102004033585 describes a method for automatically determining a color, characterized in that at least one color to be determined and one or more reference colors, such as grayscales G1 to G16, red, yellow, blue, white and / or black, are recorded in a computer-readable manner, a computer program installed on a data processing device reads the recorded data, compares the recorded data of at least a portion of the reference colors with stored reference color comparison values, and the color is automatically determined by evaluating at least a portion of the recorded data of the color to be determined and at least a portion of the difference values ​​determined in the comparison between the read data and the stored comparison values.

[0024] Known dermatoscopes include one or more magnifying lenses and an illumination system for precise observation of the skin. They do not include cameras, electronic sensor processors, or software applications capable of determining the color of a skin target. Furthermore, they are not small or lightweight enough for personal use. US2004 / 0062056 describes a dermatoscope having several LEDs arranged around an optical device for indirect illumination of the skin target. A light waveguide, consisting of a perforated tapered prism with its end facing the skin target, is provided in front of each LED, along with a contact plate composed of glass or transparent plastic. FR2826856 describes a dermatoscope comprising: an atlas having a plurality of image reference devices or means for displaying reference images; and a portable optical instrument for direct observation of a skin area, including means for generating an image of the skin target that can be compared with a reference image. The skin target can be illuminated by illumination means having different inclinations. The optical instrument includes at least one screen that can be inserted between the light source and the skin target so that the skin target is illuminated only by diffuse light from beneath the screen. This type of dermatoscope does not ensure sufficiently uniform illumination of the skin target and cannot measure skin color.

[0025] US9445749 and other related patents or patent applications by the assignee of the same name describe a smartphone accessory suitable for and intended to be associated with a smartphone for measuring the color of a sample target. The accessory includes an opaque housing so that when the sample target is positioned therein, the accessory is opaque to the exterior of the accessory and can be removably attached to the smartphone in a manner that at least optically couples the smartphone accessory to the smartphone camera. Given that insufficient uniformity of the illuminated sample target can affect colorimetric measurements, three possible arrangements are provided. In the first arrangement, an indirect optical path is provided within the design that redirects light from the smartphone flash around a portion of the wall structure in the accessory housing to illuminate the rear surface of the sample target with diffuse light. A second arrangement also utilizes a flash to illuminate the sample target, with a diffuser (not described in detail) incorporated between the flash and the front surface of the sample target. A third arrangement utilizes LEDs mounted in the accessory housing behind the sample target, with a light diffuser positioned between the LEDs and the rear surface of the sample target. In the final arrangement, the accessory includes not only the LEDs but also a battery. This smartphone accessory is specifically designed for measuring and analyzing sample targets, such as analytes, such as bodily fluids like sweat, saliva, urine, and blood. To this end, a modular test platform is provided for the target, such as a test strip with a test area and a calibration area for receiving the target analyte, with the appropriate chemistry and shape for use in the smartphone and achieving a specific colorimetric reaction. Furthermore, this smartphone accessory is not intended, suitable, or capable of measuring the color of skin targets. Finally, this smartphone is not suitable for personal use.

[0026] EP1866637 describes a similar smartphone accessory, suitable and intended for use with a smartphone, to measure the color of a test strip (sample target) housed within a removable test stick. The device can also operate in either transmission or reflection mode, depending on whether the light beam is transmitted through or reflected from the test strip. The LED is located within the accessory and is associated with polarized glass or a plate to disperse the light. This accessory has the same drawbacks and limitations as described above.

[0027] The article "A Smarthone-Based Automatic Measurement-Method for Colorimetric pH Detection Using a Color Adaptation Algorithm" by Sung Deuk Kim and al outlines a device for measuring the color of pH indicator paper (sample target) based on comparison with a colored reference target paper located to its side, where a camera simultaneously takes photos of the pH indicator paper (sample target) and the colored reference target paper.

[0028] US2003 / 0169421 describes a spectrophotometer in which the electronic circuitry and LEDs are housed in a standard housing and mounted on a common circuit board. Several LEDs are arranged in a circular pattern concentric with the collection channel. The light from each LED is directed through a filter. A diffraction disk is located in the light path after the LED and mixes the light beams at a certain angle. A first condenser captures the light. A second imaging system, consisting of an imaging lens and a redirecting mirror, then creates a limited illumination point in the measurement target at a specific angle of incidence (i.e., 45°). This spectrophotometer is also not suitable for quick, easy, inexpensive, accurate, and automatic measurement of the color of a skin target by the user themselves using a smartphone accessory.

[0029] There is a need for a device for measuring the color of an AOI target of original, unaltered material, such as a skin target, from the outside, particularly for cosmetic or similar applications, which device is inexpensive, lightweight, easy to operate and handle, accurate, and can be used by the user themselves, typically at home, using an existing smartphone having a camera and flash, and a downloaded application suitable for measuring the colors in a photograph (or arranged to enable transmission to a different location or different processing device where appropriate processing procedures for measuring the colors in the photograph are performed), the device being functionally and structurally associated with a smartphone accessory.

[0030] Regarding US2017 / 085761, the problem to be solved is to enable a smartphone accessory to measure the color of an AOI target (here skin), the measurement being based on a comparison of the color of the AOI target with N appropriately known and selected colors of a color measurement target on the same photograph obtained under the same lighting conditions (i.e., light uniformly distributed within the range of the AOI target and the color measurement target). Summary of the Invention

[0031] According to one aspect, the subject of the present invention is a mobile phone accessory suitable and intended to be functionally and structurally associated with a portable digital device capable of running a program for performing functions, such as a smartphone with a camera and a flash, and suitable and intended to be associated with an area of ​​interest AOI target of a material M, and comprising:

[0032] a support and handling housing having an opaque wall defining an interior space that is not disturbed by external light when in use, the wall having an inner face and including an aperture suitable and intended for association with the material M and the AOI target and located within the light entrance point, and a rear wall portion,

[0033] an illumination member having an illumination axis, arranged at least partially in said housing and adapted and intended, in use, to generate light illuminating said light entry point,

[0034] a camera field of view member having a field of view axis, arranged at least partially in said housing and adapted and intended for taking a reflected photograph of said light entry point and its contents,

[0035] A diffuser plate, located within the housing, is adapted and intended to be functionally associated with the illumination member when in use, has a diffuser opening in which the center of the camera field is at the intersection of the field of view axes and the illumination center is at the intersection of the illumination axes, and includes a high-opacity portion located near the illumination member and a low-opacity portion located at the periphery of the high-opacity portion.

[0036] This mobile phone accessory is characterized by the following features:

[0037] The housing comprises a front wall portion which extends towards the rear wall portion and is spaced apart from the rear wall portion and in which the hole, i.e. the measuring hole, is located.

[0038] The outer portion of the front wall portion includes an area surrounding the measurement aperture, which is suitable and intended to be in contact with the material M located externally around the AOI target and is suitable and intended to hide any passage of external ambient light,

[0039] The mobile phone accessory includes N color measurement targets, which are located in the internal space and fixed on the inner surface of the front wall portion having the measurement hole on the side, and together form a color measurement area unit.

[0040] the light entrance point with the measurement aperture and, in use, with the AOI target and N color measurement targets located within the camera field of view member as seen through the scattering opening,

[0041] The scattering plate has varying opacity, wherein a portion or region on and around the illumination center has high opacity, and a portion or region opposite and near the scattering opening has low opacity, and the opacity decreases continuously from the portion or region with high opacity to the portion or region with low opacity. The scattering plate also makes the illumination within the AOI target range and the N color measurement target ranges uniform.

[0042] Therefore, the mobile phone accessory is suitable and intended to allow taking pictures of the illuminated AOI target and the illuminated N color measurement targets under the same uniform lighting conditions.

[0043] According to an embodiment, the high-opacity portion and the low-opacity portion have unequal opacities in terms of their range, the scattering plate has high opacity in the area on and around the illumination center, has low opacity in the area opposite to the area and near the scattering opening, and has continuously decreasing opacity in the area from the high-opaque area to the low-opaque area.

[0044] According to an embodiment, the opacity of the diffuser plate varies continuously or discretely.

[0045] According to an embodiment, the opacity of the high-opacity portion or its area is greater than the opacity of the low-opacity portion or its area, i.e. greater than 70%, particularly greater than 80%, particularly greater than 90%, particularly equal to or close to 100% (at which time it is opaque).

[0046] According to an embodiment, the opacity of the low-opacity portion or its region is less than the opacity of the high-opacity portion or its region, i.e. less than 70%, particularly less than 10%, particularly equal to or close to 0% (completely transparent at this time).

[0047] According to an embodiment, the opacity of the diffusion plate varies from completely opaque to completely transparent.

[0048] According to an embodiment, the diffuser plate is made of a plastic material filled with light-shielding pigments at a desired density to obtain a suitable opacity variation.

[0049] According to another embodiment, the diffuser plate comprises a transparent back surface on which is fixed a portion of film or dots of a certain opacity to allow obtaining an appropriate opacity variation. As one possibility, the diffuser plate alternates high opacity portions with low opacity portions in order to create an opacity that is averaged between them.

[0050] According to an embodiment, the mobile phone accessory does not include a light source such as an LED inside, and the light source is outside the accessory, such as a flashlight of a smartphone.

[0051] According to an embodiment, the camera field of view member includes a camera window located in the rear wall portion, adapted and intended to pass through the field of view of a camera external to the accessory, such as a camera of a smartphone, the mobile phone accessory being characterized in that it does not include a camera internally.

[0052] According to an embodiment, the camera field of view member comprises a lens to have semi-focus on the center of the AOI target and on the centers of at least a substantial number, if not all, of the N color measurement targets (e.g., most of such targets).

[0053] According to an embodiment, N appropriate color measurement targets sufficient to allow accurate measurement of the color of the AIO target are selected to have defined colors within a narrow color gamut representing the entire AOI target color range, and the color measurement targets collectively form a color measurement area unit. Therefore, the mobile phone accessory is suitable and intended to measure the color of the AOI target by allowing photographs of the illuminated AOI target and the N illuminated color measurement targets to be taken under the same lighting conditions, and processing such photographs to compare the color of the photographed AOI target with the color of the photographed color measurement targets of the color measurement area unit, so as to measure the color of the AOI target.

[0054] According to an embodiment, the color measurement targets are arranged side by side along at least one line of the color measurement area unit, while the color measurement targets belonging to two consecutive lines are arranged side by side.

[0055] According to an embodiment, the radius of the color measurement area unit is larger, firstly smaller than 4 times, in particular smaller than 3 times, and secondly larger than 2 times the radius of the measurement aperture.

[0056] According to an embodiment, the number N of color measurement targets sufficient to allow accurate measurement of the color of the AIO target is at least 20, less than 50, particularly less than 40, particularly less than 30, particularly equal to or close to 25.

[0057] According to an embodiment, one color measurement target is in the form of a dot, with a width smaller than 1 cm, in particular smaller than 0.7 cm, in particular smaller than 0.5 cm, in particular equal to or close to 0.2 cm.

[0058] According to an embodiment, the mobile phone accessory is characterized by a method for realizing a color measurement area unit of N color measurement targets, the method comprising the following steps:

[0059] Make a large number of several basic color materials available, from which a certain proportion of basic color materials can be extracted.

[0060] making available a substrate, either the housing or a separate substrate which is subsequently fixed to the housing,

[0061] preparing N portions of fine color materials from basic color materials by mixing specific identified basic color materials in sufficient proportions so that the color of each portion of the fine color material exactly matches the color of the intended color measurement target,

[0062] A small amount of fine color material is sampled from each of the N portions to obtain N available samples of the small amount of fine color material,

[0063] N fine color material samples are deposited onto a substrate in a proper order and arrangement so as to form N color measurement area units of a color measurement target.

[0064] According to another aspect, the present invention is directed to an apparatus for measuring the color of an AOI target, which is an area of ​​interest of a material M, the measurement being performed relative to appropriate N color measurement targets having defined colors within a narrow color gamut representing the entire color range of the AOI target, by performing illumination and light reflection on the AOI target and the N color measurement targets, and photographs of the illuminated AOI target and the illuminated color measurement targets, under identical uniform lighting conditions, processing such photographs to compare the color of the photographed AOI target with the color of the photographed color measurement targets of the color measurement area units, so as to measure the color of the AOI target, the apparatus comprising:

[0065] a smartphone capable of running a program for performing the function, such as a smartphone having a camera and flash and appropriate processing software for measuring the colors in a photograph,

[0066] Mobile phone accessories, as already described, and

[0067] A removable connecting member is provided for fixing the mobile phone accessory to the smartphone, in particular being integral with the accessory.

[0068] According to an embodiment of the device:

[0069] The light for illuminating the AOI target and the N color measurement targets is a flash of the smartphone,

[0070] The camera that takes the picture of the illuminated AOI target and the N color measurement targets is the camera of the smartphone,

[0071] The arrangement of the mobile phone accessory allows the light beam generated by the flash of the smartphone to pass through the field of view of the camera of the smartphone,

[0072] An appropriate processing program, such as an application, for measuring the colors in the photograph is loaded on the smartphone rather than on the mobile phone accessory.

[0073] According to another aspect, the subject of the invention is a method for measuring the color of an AOI target being an area of ​​interest of a material M, wherein:

[0074] making available a material M, an area of ​​interest AOI containing such material,

[0075] Making available a smartphone capable of running a program for performing the function, such as a smartphone with a camera and flash, loaded with a suitable processing program, such as an application, for measuring the colors in the photograph,

[0076] Making the mobile phone accessory available for use, as already described,

[0077] structurally associating the smartphone and the mobile phone accessory by means of the removable connecting member,

[0078] applying the material M and the mobile phone accessory to each other so that the material M is located on the outer surface of the housing and the AOI target is located in front of the measuring hole,

[0079] commanding the smartphone to use a flashlight and a photo to illuminate and reflect light on the AOI target and the color measurement target and the photo of the illuminated AOI target and color measurement target under the same uniform lighting conditions,

[0080] And, using an appropriate processing program for measuring colors in the photograph, the photograph is processed to measure the colors of the AOI target.

[0081] According to an embodiment of the method, said material M is human skin, and wherein said method is performed by this human to measure the color of said skin.

[0082] According to another aspect, the invention relates to a photograph of an AOI target and N color measurement targets, the photograph being obtained by means of the device already described, the photograph being suitable for processing using a suitable processing procedure for measuring the colors in the photograph, the photograph comprising two adjacent areas, one showing the photographed AOI target and one showing the photographed N color measurement targets. BRIEF DESCRIPTION OF THE DRAWINGS

[0083] Figure 1A and 1BRespectively, rear and front perspective views of a smartphone structurally associated with a mobile phone accessory via a removable connecting member according to the present invention, the smartphone and the mobile phone accessory together forming an apparatus for measuring the color of an area of ​​interest (AOI) of a material M relative to N color measurement targets.

[0084] Figure 2 is a perspective exploded view showing the back of a smartphone and a mobile phone accessory, the smartphone and mobile phone accessory not being structurally related but with arrows indicating such connection, without showing removable connecting members, and in the case of the smartphone, showing a camera lens and flash.

[0085] Figure 3A 、 3B 3C are three external views of the mobile phone accessory with the removable connecting member installed, namely the front, rear and side views. The figure shows the outside of the housing of the mobile phone accessory. Figure 3A The front wall portion of the housing and the measuring chamber are shown in more detail. Figure 3B More particularly shown are the rear wall portion of the housing, the camera window and the lighting window. Figure 3C The peripheral wall portion of the housing is shown in more detail.

[0086] Figure 4 is similar Figure 3C , showing a material whose color must be measured, such as human skin, which is in contact with the outer surface of the front wall portion of the housing, and the AOI target corresponding to the measurement hole.

[0087] Figure 5A This is a cross-sectional view of a mobile phone accessory, adjacent smartphone components, materials in contact with the outer surface of the housing's front wall, and the intermediate reference plane of the AOI target corresponding to the measurement aperture. For a mobile phone accessory, this diagram shows the housing, measurement aperture, color measurement area, light entry point, camera field of view, illumination window, camera window, and diffuser. For a smartphone, this diagram shows the housing components in contact with the mobile phone accessory, the camera lens, and the flash. Figure 5B It is a cross-sectional view of the mobile phone accessory and the adjacent parts of the smartphone (housing) according to a transverse plane perpendicular to the reference plane.

[0088] Figure 6 is based on Figure 5A The view of arrow F shows a diffuser plate with juxtaposed high-opacity parts and areas and low-opacity parts and areas, wherein the opacity OPA% varies continuously from completely opaque to completely transparent, and the diffuser plate also has a diffuser opening through which the light incident point with the measurement aperture and the color measurement target can be seen, just like a camera field of view. Figure 6 In the figure, the position of the illumination window is indicated by a dotted line.

[0089] Figure 7 is a perspective view of the inner face of the housing front wall portion and its peripheral wall portion, showing the light incident point with the measurement aperture and the color measurement target.

[0090] Figure 8A 、 8B 8C and 8D are front and rear elevation views of the diffuser plate and two side views of the diffuser plate, respectively. The figures show the contour of the diffuser plate, its diffuser openings, its opacity variations, and the protrusions at its rear that are structurally associated with the housing. Figure 8E yes Figures 8A to 8D A perspective view of a diffuser plate symbolically illustrating how the diffuser plate is implemented to obtain variations in opacity.

[0091] Figure 9 FIG1 is an elevation view of a diffuser plate according to a possible embodiment, showing the variation of its opacity OPA%, namely, two extreme opacities of 100% and 0%, and eight intermediate opacities with decreasing opacities between the two, namely, 91%, 67%, 37%, 31%, 27%, 20%, 14% and 9%. Figure 9 In the figure, the position of the illumination window is indicated by a dotted line.

[0092] Figure 10A 、 10B and 10C is Figure 9 Three elevational views of three possible but non-limiting other embodiments of the scattering plate. In the figures, possible positions of the illumination windows are indicated by dotted lines. Figure 10A In the embodiment, the scattering plate includes a completely opaque portion around its conical side up to the scattering opening, a completely transparent portion near the scattering opening and the spherical side, and a continuously changing intermediate opacity portion. Figure 10B In the example, there are two extreme opacity levels, 100% and 0%, and an intermediate opacity level, here 18%, with a discrete transition. These three schemes illustrate the many possible arrangements of diffusers at varying opacities. The dotted line indicates the location of the illumination window.

[0093] Figures 11A to 11H Figures 1 and 2 show eight alternative embodiments of the diffuser. In these figures, the schematic circles represent illumination windows or light sources, and the double arrows represent light incident points. According to an embodiment, the diffuser is flat ( Figure 11B 、 11D , 11F and 11H) or curved (Figs. 11a, 11C, 11E, 11G). According to an embodiment, the opacity OPA% varies continuously ( Figure 11D 、 11E ) or discrete changes ( Figure 11A 、 11B, 11C, 11F, 11G, 11H).

[0094] Figure 12A 、 12B and 12C are three schemes representing the consecutive steps for depositing a fine color material sample onto a base member according to a first possible variant embodiment, wherein the base is a solid support provided with side-by-side perforations, and the sample of the fine color material is solid and has a shape complementary to the shape of the base holes.

[0095] 13a, 13B and 13C are three schemes representing successive steps according to a second possible variant embodiment, wherein the substrate is a solid support provided with open cavities opening on its receiving surface, and the sample of fine color material is liquid and deposited into the cavities.

[0096] Figure 14A 、 14B and 14C are three schemes representing successive steps according to a third possible variant embodiment, in which the substrate may be the housing itself.

[0097] Figure 15 It is a photo taken with a smartphone, which includes the photographed AOI target and N color measurement targets. DETAILED DESCRIPTION

[0098] As described above, the descriptions and meanings of words used must be included according to the field of the invention, the general knowledge of those skilled in the art, and the context of the invention.

[0099] The description is made with reference to an embodiment in which the color measurement of the AOI target is performed by measuring the area of ​​interest of a generally flat surface S of an original, unaltered material M (hereinafter referred to as "material") from the outside relative to N color measurement targets 17 by illuminating and reflecting light on the AOI target and the N color measurement targets 17, taking a photograph of the illuminated AOI target and the N color measurement targets 17 ( Figure 15 ), and undergo appropriate processing procedures for measuring the colors in the photograph. According to one possible application, the material M whose color is measured is human skin, the measurement of its color being more particularly intended for cosmetic or similar purposes.

[0100] As shown, mobile phone accessory 1 is adapted and intended to be functionally and structurally associated with smartphone 2, or more generally, with a portable digital device or multi-functional mobile device, during use, capable of executing programs for performing functions through an operating system. The phrase "adapted and intended" used with respect to a particular component that incorporates one or more technical, functional, and / or structural characteristics and / or applications and / or purposes must be interpreted as meaning that the component is arranged, designed, constructed, and implemented so that, during use, it possesses or can possess these functional and / or structural characteristics, and / or is used or can be used for such applications, and / or achieves or can achieve such purposes. Therefore, even without specific mention or description of these characteristics, applications, or purposes, the particular component implicitly implies features that enable them. The phrase "use" must be interpreted as meaning that color measurement of an AOI target can be performed, such as when the flash is on and the camera is turned on. The term "associated" with respect to two components must be interpreted as meaning that the two components are connected in some manner for a common purpose or result, i.e., that the components are functionally and / or structurally combined. The term "functional" refers to a method of operation that produces a specific result. The term "structural" refers to the material implementation or arrangement.

[0101] The present invention also relates to a mobile phone accessory 1 itself, and to a device 1+2 comprising a structurally and functionally well-combined mobile phone accessory 1 and a smartphone 2, which can be used autonomously, i.e., a user of the device 1+2 can handle and move the device independently, and can ensure that the color of an AOI target can be measured even without another device or electrical connection to another device. The present invention also relates to a method for implementing the device 1+2 to measure the color of an AOI target. The present invention also relates to the specific application of the device 1+2 or the method for measuring human skin color. The present invention also relates to photographs obtained using the device that allow the color of an AOI target to be measured.

[0102] When structurally combined, smartphone 2 and mobile phone accessory 1 are handled as a single unit. For this purpose, a removable connecting member 3 is provided for securing mobile phone accessory 1 to smartphone 2. According to the example shown in the drawings, such a member comprises dual cards 3a and 3b, which also exert a biased retaining force on mobile phone accessory 1 and smartphone 2. For example, dual connecting cards 3a and 3b are elastically deformable and may comprise two integrally formed vertical sections, each having a ring sector shape. One such ring sector is adapted and intended to be secured around mobile phone accessory 1, while the other ring is adapted and intended to be used to clamp smartphone 2. According to various embodiments, such dual cards 3a and 3b may be either a separate component, distinct and separate from mobile phone accessory 1 and smartphone 2, or integrally formed with the housing of mobile phone accessory 1 or smartphone 2.

[0103] Smartphone 2 internally comprises a housing 4 having, among other things, control, navigation, and function buttons and touch elements 5, function ports, a front face 6 with a display 7 providing tactile touch, and a rear face 8 with a camera lens 9 and a flash 10, which can be used in conjunction with mobile phone accessory 1. Smartphone 2 can be a standard smartphone available on the market. Smartphone 2 also includes a suitable processing program, such as a loaded application, for measuring colors in photographs. This suitable processing program for measuring colors in photographs is based on the principle of measuring the color of an AOI target by comparing the color of the photographed AOI target with the color of a color measurement target 17 of a color measurement area unit 17a. The photographed AOI target and the photographed color measurement target 17 are located in the same photograph taken under the same lighting conditions. The same lighting conditions mean that the light is evenly distributed within the AOI target and the color measurement target 17, resulting in accurate colors for all targets. According to a different but equivalent embodiment, instead of loading an application on smartphone 2, an arrangement is provided in which smartphone 2 is transmitted to a different location or processing device, where the suitable processing program for measuring colors in photographs is performed.

[0104] Suitable processing programs for measuring color in photographs are known to those skilled in the art or readily available. The term "color measurement target 17" is used with the qualifier "measurement" because the function of this target 17 is to accurately measure the color of the AOI target using another processing program under the same uniform lighting conditions using a common photograph of the AOI target and the color measurement target 17. Mobile phone accessory 1 itself does not load or contain any color measurement processing programs.

[0105] For the purpose of describing the mobile phone accessory 1 , reference is made to its main reference plane P. The main reference plane P is substantially parallel to the substantially flat surface S of the material M.

[0106] The mobile phone accessory 1 includes a housing 11 that supports and protects the components or members of the mobile phone accessory 1. The housing 11 is also a handling member that allows the user to easily and quickly connect or disconnect the mobile phone accessory 1 to the smartphone 2.

[0107] The housing 11 includes an opaque, rigid outer wall, for example, made of a plastic material, which defines an interior space 11a. The components or elements of the mobile phone accessory 1 are housed within this interior space 11a. This interior space 11a is designed to be shielded from light (ambient light) from outside the accessory during use. On one hand, the interior space 11a can be virtually divided into a so-called illumination side 12a and a so-called camera field of view side 12b, both communicating with each other without any physical separation. On the other hand, the interior space 11a can be virtually divided into a so-called target side 12c (AOI target and color measurement target 17) and a so-called scattering and camera side 12d. The walls of the housing 11 and the housing 11 itself have an inner surface 13a and an outer surface 13b. The inner surface 13a flanks the interior space 11a and is non-reflective, for example, having a matte black finish. The outer surface 13b is accessible to the user's hand and can come into contact with the material M containing the AOI target. It may also be matte black. The wall of housing 11 comprises several sections arranged in series: a front wall section 14a, a rear wall section 14b, and an annular peripheral wall section 14c. Front wall section 14a and rear wall section 14b extend substantially parallel to and parallel to reference plane P. They at least partially face each other, are spaced apart from each other, and are connected by peripheral wall section 14c, which determines the spacing between front wall section 14a and rear wall section 14b and must be adapted to optical requirements. The qualifiers "front" and "rear" with respect to wall sections 14a and 14b are not restrictive. They are used to distinguish between the two wall sections 14a and 14b. The qualifier "front" relates to wall section 14a that faces material M. The qualifier "rear" relates to wall section 14b that faces away from front wall section 14a. Front wall section 14a and its inner and outer surfaces 13a and 13b extend at least substantially flat along a substantial length (not just along the edges) in both directions along reference plane P. According to an embodiment, the inner face 13a of the front wall portion 14a extends at least substantially flat, while being curved with a small recess facing the interior space 11a.

[0108] Said arrangement allows the housing 11 and the mobile phone accessory 1 to have the general shape of a half-truncated sphere, with opposite sides being spherical (on the side of the rear wall portion 14b) and conical (on the side of the front wall portion 14a), as shown in the accompanying drawings ( Figure 2 、 3B, 4, 5A and 5B). This general shape allows for the correct positioning of the components or members of the mobile phone accessory 1. This general shape is also ergonomic, allowing the housing 11 to be easily manipulated in the palm of the hand. This general shape is contained within an enclosure having a length of approximately 4.2 cm, a width of approximately 3 cm, and a thickness of approximately 2.7 cm. The entire housing 11 is obtained by the rigid assembly of two half-shells, which cannot be disassembled under normal circumstances. One half-shell 11b is located on the target side 12c and includes a front wall portion 14a, and the other half-shell 11c is located on the scattering and camera side 12d and includes a rear wall portion 14b.

[0109] When in use, the front wall portion 14a forms an at least substantially flat light entry point 15, which is located substantially within the illumination side 12a and the target side 12c. Light entry point 15 refers to a generally circular area on the back surface or the support that is illuminated more intensely than adjacent areas due to the incident light beam being directed onto it. In other words, the fact that the front wall portion 14a forms light entry point 15 means that when the light beam is directed onto the inner surface 13a of the front wall portion 14a, it strikes the inner surface 13a and the material M located in front of the measuring aperture 16, forming light entry point 15. Light entry point 15 has a so-called point center 15a.

[0110] Front wall portion 14a includes a through-hole 16, which is typically generally circular or polygonal in shape. It is located within the light entry point 15 and opens onto both the illumination side 12a and the target side 12c. Through-hole 16 is generally located in the central portion of front wall portion 14a, its area being limited to a portion of the area of ​​front wall portion 14a. Measurement hole 16 has a center, namely, point center 15a. Measurement hole 16 is suitable and intended for use with material M, its AOI target, and color measurement target 17. Measurement hole 16 enables the AOI target, located outside housing 11, to be illuminated from interior space 11a, thereby becoming part of and encompassing light entry point 15. The primary purpose of measurement hole 16 is to allow for color measurement of the AOI target, rather than to reveal an extended area of ​​material M (for detecting defects). The wall thickness of housing 11 surrounding measurement hole 16 is minimized to avoid any ambient occlusion of the AOI target and to allow for a similar distance between the camera, the AOI target, and the N color measurement targets 17. According to an embodiment, a thickness of approximately 1 mm is suitable. The color measurement target 17 also illuminated from the interior space 11 a is also part of the light incident point 15 and is included therein.

[0111] On the outer surface 13b of the front wall portion 14a of the housing 11, a region surrounding a measurement aperture 16 is provided, extending at least substantially in both directions from the reference plane P. In one possible embodiment (not shown), the surrounding region may include a continuous, annular soft rim adapted and intended to allow the mobile phone accessory 1 to contact the material M located externally around the AOI target and to conceal any external ambient light from passing between the outer surface 13b of the housing 11 and the material M in contact therewith. When the material M and the rim are in contact with each other, the AOI target is visible from the interior space 11a through the measurement aperture 16, and the AOI target is illuminated solely by the light beam forming the light entry point 15, which contains the AOI target and the color measurement target 17, rather than by ambient light. According to the example shown in the drawings, the outer surface 13b of the housing 11 may simply be flat and smooth to ensure sufficient contact with the material while preventing the passage of ambient light, rather than providing a specific rim. According to the example shown in the drawings, the radius of the measurement aperture 16 may, by way of example, be between 3 cm and 6 cm, particularly between 4 cm and 5 cm, and particularly equal to or approximately 4.5 cm. The outer radius of the front wall portion 14 a may be, for example, three to five times the radius of the measuring hole 16 (possibly even larger).

[0112] According to the example shown in the drawings, the mobile phone accessory 1 internally contains N color measurement targets 17. These N color measurement targets 17 have defined colors within a narrow color gamut that represents the entire color range of the AOI target. These N color measurement targets 17 collectively constitute a so-called "color measurement area unit" 17a, reflecting the fact that these N color measurement targets 17 must be considered functionally as a unit to allow for color measurement of the AOI target and structurally form an area. The N color measurement targets 17 are selected to provide accurate values ​​for the color of the AOI target. As an example, N is at least 20 and less than 50, particularly less than 40, and even more particularly less than 30. Specifically, according to an embodiment, N is equal to or approximately 25, a number of color measurement targets 17 suitable for accurate color measurement of AOI targets, such as skin targets. The N color measurement targets 17 are located within the illumination side 12a and target side 12c of the interior space 11a and are secured to the inner surface 13a of the front wall portion 14a. The present invention is based on selecting appropriate and sufficient N color measurement targets 17 and selecting appropriate limiting colors within a narrow color gamut representing the entire AOI target color range, so that the color of the AOI target can be measured using the color measurement area unit 17a.

[0113] According to one possible embodiment, the N color measurement targets 17 are directly affixed to the inner surface 13a of the front wall portion 14a. According to another possible embodiment, the N color measurement targets 17 are indirectly affixed to the inner surface 13a of the front wall portion 14a via an intermediate substrate. In the latter case, the N color measurement targets 17 are first affixed to the substrate, and then the substrate containing the N color measurement targets 17 is affixed to the inner surface 13a of the front wall portion 14a. In this case, the mobile phone accessory 1 initially does not contain the N color measurement targets 17, but they are reported later.

[0114] N color measurement targets 17 are placed within the light incident point 15 and adjacent to, near, and around the measurement aperture 16. Therefore, a color measurement area unit 17a is also placed within the light incident point 15 and adjacent to, near, and around the measurement aperture 16. Typically, the color measurement area unit 17a is annular, specifically circular or polygonal in shape. The color measurement area unit 17a has a center, which is also the point center 15a.

[0115] According to the example shown in the drawings, N color measurement targets 17 are arranged side by side along at least one line (eg, a circle) of the color calibration area unit 17a, and there are several such lines (eg, Figure 6 The color measurement targets 17 belonging to the two continuous lines are arranged crosswise and side by side (see Figure 6 ). On the one hand, according to an embodiment, first, the maximum radius of the color measurement area unit 17a is less than 4 times, and particularly less than 3 times, the radius of the measurement hole 16. Secondly, the maximum radius of the color measurement area unit 17a is greater than 2 times the radius of the measurement hole 16. For example, the maximum radius of the color measurement area unit 17a is approximately 2.5 cm. On the other hand, according to an embodiment, the radius of one color measurement target 17 is less than 1 cm, particularly less than 0.7 cm, particularly less than 0.5 cm, and particularly equal to or close to 0.2 cm. Therefore, the volume of each color calibration target can be approximately 13 to 15 mm. 3 .

[0116] There are various ways of implementing N color measurement targets 17, that is, implementing N color measurement targets 17 fixed to the inner face 13a of the front wall portion 14a using the arrangement described above. According to one possible embodiment (which itself may be the subject of a number of variant embodiments), this implementation method comprises the steps now described.

[0117] The method begins with the availability of a large quantity of several liquid primary color materials, from which certain proportions of primary color materials can be extracted. These primary color materials are required to obtain a material having N color measurement targets 17 by mixing appropriate quantities of these materials. In other words, the different colors of the primary color materials are selected to obtain a material having N colors within a narrow color gamut that represents the entire AOI target color range. Once the manufacturer of the mobile phone accessory 1 for color measurement knows the types of materials to be used in the device 1+2, they can determine the necessary colors of the primary color materials themselves or obtain them from color measurement experts with color measurement targets, and further acquire sufficient primary color materials.

[0118] The method described requires the availability of a solid substrate 18. The substrate 18 must be suitable and intended to receive and hold the N color measurement targets 17 and ultimately allow the N color measurement targets 17 to be fixed to the inner face 13a of the front wall portion 14a in the arrangement described previously. To this end, the substrate 18 has a flat receiving surface 18a, to which the N color measurement targets 17 are fixed. According to one possible variant embodiment, the substrate 18 is the housing 11 itself, or more precisely, the portion of the housing 11 at the light entrance point 15. The receiving surface 18a of the substrate 18 is then the inner face 13a of the housing 11. According to another possible variant embodiment, the substrate 18 is not the housing 11 itself, but rather a separate solid support 18 that is suitable and intended to be fixed to the inner face 13a of the housing 11 at the light entrance point 15 later (when decorated with the N color measurement targets 17). This solid support or base 18 can be a thin plate or film, one side of which is a receiving surface 18a and the other side surface 18b is a fixing surface on the inner surface 13a of the housing 11. According to these implementation forms, the solid support or base 18 is stable in shape or has a certain flexibility so as to perfectly match the shape of the inner surface 13a of the front wall portion 14a.

[0119] The method continues by preparing N portions of fine color materials from the primary color materials by mixing sufficient and precise proportions of the specific identified primary color materials so that the color of each of the N portions of fine color materials is exactly the same as the color of the intended color measurement target.

[0120] The method continues by sampling a small amount of fine color material from each of the N portions. By doing so, N small amounts of fine color material samples are ultimately obtained, the colors of which are exactly the same as the colors of the N color measurement targets 17, which can be used to realize the N color measurement targets 17 on the substrate 18.

[0121] The combination of these operating steps has the advantage, among other things, that a large number of fine color materials having precisely required colors can be processed, thereby realizing a large number of color measurement targets 17 which also have precisely required colors.

[0122] The method continues by depositing the N fine color material samples thus achieved onto the substrate 18 in a suitable order and arrangement to form a color measurement area unit 17 a having N color measurement targets 17 on the inner face 13 a of the outer wall of the housing 11 .

[0123] According to a first possible variant embodiment ( Figure 12A 、 12B and 12C), the substrate 18 is a solid support provided with side-by-side perforations 18 c arranged in a pattern identical to the desired pattern of the N color measurement targets 17. The N fine color material samples are solid and have shapes complementary to the shapes of the holes 18 c of the substrate 18. Here, depositing the N fine color material samples onto the substrate means introducing each solid sample of the fine color material into a hole.

[0124] According to a second possible variant embodiment ( Figure 13A 、 13B 13C), the substrate 18 is a solid support having recesses 18d opened on a receiving surface 18a, the recesses being arranged in a pattern identical to the desired pattern of the N color measurement targets 17. The N fine color material samples are in a liquid state. Here, depositing the N fine color material samples onto the substrate means depositing each liquid sample of the fine color material into a recess 18d and eventually hardening it.

[0125] In the first and second embodiments, the solid support or base 18 decorated with the N color measurement targets 17 is further securely fixed in place to the inner surface 13a of the outer wall by ultrasonic welding, gluing, or any other equivalent fixing means. The solid support or base 18 may be a single piece or comprised of multiple components, as appropriate.

[0126] According to a third possible variant embodiment ( Figure 14A 、 14Band 14C), the substrate 18 is the housing 11 itself, or more precisely, the portion of the housing 11 at the light incident point 15, and the receiving surface 18a is the inner surface 13a of the housing 11. The N fine color material samples are in liquid form. Here, depositing the N fine color material samples onto the substrate means depositing each liquid sample of the fine color material at an appropriate location on the inner surface 13a of the housing 11 and eventually hardening it. In this variant embodiment, a component suitable for and intended to deposit N color measurement targets 17 in a desired order and arrangement is provided. Such a component may be or include a programmed robot and / or a small open cavity on the inner surface 13a of the housing 11. Such a programmed robot may include a method for depositing the N color measurement targets 17.

[0127] According to another embodiment not shown, the mobile phone accessory 1 comprises means which are functionally, in particular structurally, associated with the N color measurement targets 17. In such an embodiment, the mobile phone accessory 1 does not initially contain the N color measurement targets 17 inside.

[0128] Mobile phone accessory 1 also includes a camera field of view 19 having a field of view axis 19a. According to the example shown in the figures, this field of view axis is perpendicular to reference plane P and lies within camera field of view side 12b of interior space 11a. Camera field of view 19 is arranged within housing 11. The term "field of view" in relation to a camera, which can also be referred to as "field of view" or "angle of view," corresponds to the spatial area perceived by the camera. It is the solid angle to which the camera is sensitive to light. Camera field of view 19 is associated with the camera external to mobile phone accessory 1, namely, the camera of smartphone 2 with camera lens 9. Therefore, mobile phone accessory 1 does not contain a camera internally.

[0129] The rear wall portion 14b includes a camera window 20 within the camera field of view 19. The camera window 20 has a camera window center 20a and a field of view axis 19a passing through the camera window center. Specifically, the camera window 20 is generally circular or polygonal in shape. The camera window 20 opens onto the camera field of view side 12b and the diffuser and camera side 12d of the interior space 11a. The camera window 20 is adapted and intended to be associated with the camera lens 9 of the smartphone 2, i.e., to be in coaxial contact with each other and to be maintained in this state by a removable connecting member 3, thereby securing the mobile phone accessory 1 to the smartphone 2. The camera window 20 can simultaneously capture images of an AOI target and N color measurement targets 17 arranged near the AOI target. According to the example shown in the drawings, a lens 21 is provided within the camera field of view side 12b, adjacent to the inner surface 13a of the rear wall portion 14b. If necessary, such a lens 21 is required so as to have a semi-focus on the center of the AOI target (on the axis 19a) and a semi-focus on the centers of at least a considerable number (if not all) of the N color measurement targets 17 (for example, most of such targets 17). If the lens 21 is present, it is arranged in a fixed position and does not need to be moved or replaced axially by the user, and the mobile phone accessory 1 does not have a slider or equivalent member to move the lens.

[0130] On the outer face 13b of the rear wall portion 14b of the housing 11, according to an embodiment not shown, a protrusion may be provided around a camera window 20, which is adapted and intended to bring the outer face 13b of the rear wall portion 14b of the mobile phone accessory 1 into contact with the rear face of the smartphone 2. The radius of the camera window 20 may be between 0.3 cm and 2 cm. According to the examples and possible embodiments shown in the figures, the lateral distance between the rear wall portion 14b and the front wall portion 14a, more specifically, between the camera window 20 and the measuring aperture 16, relative to the reference plane P, may be between 2 cm and 8 cm.

[0131] The mobile phone accessory 1 further includes an illumination member 22, which is functionally associated with a light scattering member 23 (or 27, as shown later with respect to the plate). The illumination member 22, which is at least partially disposed within the housing 11, is adapted and intended to generate light that, when in use, illuminates the light entry point 15 and, therefore, the AOI target and the N color measurement targets 17. The light scattering member 23 is adapted and intended to scatter the light of the illumination member 22 so that the light that illuminates the light entry point 15 (and, therefore, the AOI target and the N color measurement targets 17) is uniform across its entire extent.

[0132] The illumination member 22 is associated with a light source external to the mobile phone accessory 1, since this light source is the flash 10 of the smartphone 2. Therefore, the mobile phone accessory 1 does not contain a light source such as an LED inside.

[0133] According to the example shown in the drawings, the rear wall portion 14b includes an illumination window 24 having an illumination window center 24a and an illumination axis 22a passing through the illumination window center and perpendicular to the reference plane. The illumination window 24 is part of the illumination component 22. The illumination window 24 opens onto the illumination side 12a and the diffuser and camera side 12d. According to the example shown in the drawings, the rear wall portion 14b includes an illumination window 24 having an illumination window center 24a and an illumination axis 22a passing through the illumination window center. The illumination window is part of the illumination component 22 and opens onto the illumination side 12a and the diffuser and camera side 12d.

[0134] The illumination window 24 is adapted and intended to be coaxially associated with the flash 10 of the smartphone 2, and is maintained in this position by a removable connecting member 3. The illumination window 24 allows the smartphone 2's flash 10 to illuminate the AOI target and the N color measurement targets 17. According to the example shown in the figures, the illumination window 24 does not necessarily have to be in full contact with the rear surface of the smartphone 2; a small space may exist between them. According to another possible embodiment (not shown), a protrusion surrounding the illumination window 24 may be provided on the outer surface 13b of the rear portion of the housing. This protrusion is adapted and intended to bring the outer surface 13b of the rear wall portion 14b of the mobile phone accessory 1 into contact with the rear surface of the smartphone 2. In all embodiments, the illumination window 24 is adapted and intended to transmit the light beam generated by the flash 10 of the smartphone 2. In this second embodiment, the illumination window 24 only allows the light generated by the flash 10 to pass, while preventing external ambient light from passing. In a possible embodiment, the illumination window 24 is protected by a transparent material. Depending on the possible embodiment, the size of the illumination window 24 may be between 0.3 cm and 2 cm. According to another embodiment, instead of the illumination window 24, a transparent or translucent illumination area is provided on the rear wall portion 14b located in the illumination side 12a and arranged at the same position. Like the illumination window 24, this illumination area also has an illumination axis and an illumination window center 24a.

[0135] Through the illumination window 24 or illumination area, the light beam from the flash 10 of the smartphone 2 is directed and shaped so that substantially parallel light (relative to the illumination axis 22a) enters the illumination side 12a. The arrangement of the illumination member 22, the light scattering member 23, and the camera field of view 19 is such that the light beam generated by the flash 10 and diffused by the light scattering member 23 hits the light entrance point 15 contained within the camera field of view 19, without any obstructions (such as mirrors, etc.) in between.

[0136] Regardless of the configuration and size of smartphone 2, illumination window 24 or illumination area is of sufficient size to enable functional association with flash 10 of smartphone 2. Thus, according to the example shown in the figures, illumination window 24 is rectangular. According to a possible embodiment, the distance between camera window center 20a and illumination window center 24a, i.e., the distance between field of view axis 19a and illumination axis 22a, can be between 0.8 cm and 2 cm.

[0137] The light scattering member 23 is at least partially disposed within the housing 11, and according to the example shown in the drawings, is completely disposed within the housing 11. The light scattering member 23 is adapted and intended to be functionally associated with the illumination member 22 during use. The light scattering member 23 has the function of uniformizing the illumination of the light incident point 15 and its contents (the AOI target and the N color measurement targets 17). The light scattering member 23 includes at least two extended portions 25 and 26 having different opacities (OPA%) for the light from the illumination member 22.

[0138] The term "opacity" applies to an object, such as a plate or sheet with two opposing sides, and refers to a measure of the object's ability to prevent light, such as that produced by a smartphone flash, from passing through it (from one side to the other). The higher the opacity metric, the more opaque the object. If the Opacity (OPA%) is 100%, the object is completely opaque, as no light passes through. If the Opacity (OPA%) is 0%, the object is transparent, as all light passes through. If some light, but not all, passes through the object, the object is translucent.

[0139] The expression "high opacity" here refers to an opacity OPA% between 70% and 100% in an absolute sense. The expression "higher opacity" here refers to an opacity in a relative sense, this opacity OPA% being greater than another. Conversely, the expression "lower opacity" here refers to an opacity in a relative sense, this opacity OPA% being less than another. All faces of an object may have a constant opacity OPA% or a variable opacity OPA%, i.e. higher in one or several areas of its face and lower in one or several other areas. The opacity OPA% of portions 25 and 26 and between them may vary discretely or continuously. In a possible embodiment, it may vary discretely by alternating high opacity portions with low opacity portions, thereby creating an opacity that is averaged between one of the high opacity portions and one of the low opacity portions. For example, the scattering member 23 comprises a pattern of dots having said high opacity portions ( Figure 8A and 8E ).

[0140] According to the example shown in the accompanying drawings, the light scattering member 23 is in the form of a plate 27, which is mounted on and supported by the housing 11 and is in a fixed position. It is referred to herein as the scattering plate 27. The scattering plate 27 is rigid and complete (except for the scattering opening 30 mentioned below). According to possible embodiments, the scattering plate 27 is relatively thin, for example, about 0.5 mm. According to a first possible embodiment, the scattering plate 27 is planar (i.e., extending along a plane). According to a second possible embodiment, the scattering plate 27 is curved like a portion of a cylinder or a portion of a sphere, i.e., a cap-shaped sphere. In the latter case, the axis of the cylinder or the center of the sphere is the axis passing through the center of the illumination window 24a or the center of the illumination window 24a itself. The first embodiment in which the scattering plate 27 is flat is further described.

[0141] The diffuser plate 27 is another component of the housing 11. It is structurally suitably associated with the housing 11 to maintain it in a fixed position. To this end, the housing 11 and / or diffuser plate 27 may include appropriate protrusions or recesses, or, in the case of the housing 11, may include an appropriate shape of the inner surface 13a. According to the example shown in the drawings, a collar 28a is provided as part of the housing 11, positioned around the camera window 20. This collar 28a may comprise a continuation of the inner surface 13a of the housing 11, which supports the diffuser plate 27. Furthermore, a protrusion 28b of the diffuser plate 27 is provided, which abuts against the inner surface 13a of the rear wall portion 14b. Within the housing 11 and the interior space 11a, the diffuser plate 27 is arranged parallel to the reference plane P. The diffuser plate 27 separates the diffuser and camera side 12d from the target side 12c. The diffuser plate 27 has two opposing sides: a front side 29a and a rear side 29b, surrounding a peripheral edge 29c. The front face 29a of the diffuser plate 27 faces the target side 12c, the AOI target, and the N color measurement targets 17. The rear face 29b of the diffuser plate 27 faces the diffuser and camera side 12d and the illumination window 24 or area. The qualifiers "front" and "rear" of the diffuser plate 27 are not restrictive. They are used to distinguish between the two faces 29a and 29b of the diffuser plate 27. The qualifier "front" relates to the face of the diffuser plate 27 facing the front wall portion 14a of the housing 11. The qualifier "rear" relates to the face of the diffuser plate 27 facing the rear wall portion 14b of the housing 11. The diffuser plate 27 is located at least within the illumination side 12a. However, according to the example shown in the figures, the diffuser plate 27 is located not only within the illumination side 12a but also within the camera side 12d. It also has an opening, referred to herein as a diffuser opening 30, whose location, shape, and size allow the camera field of view 19 to be unrestricted, clipped, or distorted. In other words, the diffuser opening 30 corresponds to the trajectory of the camera field of view 19 on the diffuser plate 27. The qualifier "diffuser" applied to the opening 30 is not restrictive, but serves only to distinguish the opening 30 from other holes, apertures, etc. of the accessory 1. The peripheral edge 29c of the diffuser plate 27 abuts the inner surface 13a of the housing 11 at the peripheral annular outer wall portion, and therefore, the shape of the edge resembles the shape of the housing 11 cut by the plane of the diffuser plate 27. According to the example shown in the figures, the peripheral edge 29c has a circular profile with a spherical side 31a and a conical side 31b, diametrically opposed, forming an elliptical shape (e.g., the shape of an egg). The diffuser plate 27 has two axes perpendicular to its plane and to plane P. These two axes define two relative optical centers on the diffuser plate 27 where they intersect. One of the axes is the field of view axis 19a, located on the spherical side 31a, and is also the axis of the diffuser opening 30. The other axis is the illumination axis 22a (of the illumination window 24 or illumination area), located on the conical side 31b.Thus, on the one hand, the diffuser plate 27 has a so-called associated phase field center 19aa at the intersection of the field of view axis 19a and the diffuser plate 27, which is the center of the diffuser opening 30. On the other hand, the diffuser plate 27 has a so-called associated illumination center 22aa at the intersection of the illumination axis 22a and the diffuser plate 27. The diffuser plate 27 is positioned near the illumination window 24 or the illumination area so that the light beams from the illumination window 24 or the illumination area completely hit the rear face 29b of the diffuser plate 27. According to a possible embodiment, the rear face 29b of the diffuser plate 27 may be slightly spaced apart from the inner face of the illumination window 24 or the illumination area, for example, by approximately 5 mm.

[0142] The diffuser plate 27 is arranged to include at least two extended portions 25, 26 with different opacities OPA%, namely a first high-opacity portion 25 and a second low-opacity portion 26. The high-opacity portion 25 is arranged near the illumination window 24 or the illumination area, and is located in the illumination window 24 or the illumination area (its position is Figure 6 、 Figure 9 and Figures 10A to 10C The light incident point 15 (and its contents, i.e., the AOI target and the N color measurement targets 17) is located between the high-opacity portion 25 and the rear wall portion 14b (indicated by a dotted line). The high-opacity portion 25 extends parallel to the reference plane P near the rear wall portion 14b (when the diffusion plate 27 is flat). The low-opacity portion 26 is arranged on the periphery (or a portion of the periphery) of the high-opacity portion 25.

[0143] The opacity OPA% of the low-opacity portion 26 is less than the opacity OPA% of the high-opacity portion 25, while the opacity OPA% of the high-opacity portion 25 is greater than the opacity OPA% of the low-opacity portion 26. The high-opacity portion 25 has an opacity OPA% greater than 70%, particularly greater than 80%, particularly greater than 90%, particularly equal to or close to 100% (in which case it is completely opaque). The low-opacity portion 26 has an opacity OPA% less than 70%, particularly less than 10%, particularly equal to or close to 0% (in which case it is completely transparent).

[0144] Among others, Figure 9As shown, the high-opacity portion 25 has an unequal opacity OPA% throughout its entire range, with a larger opacity OPA% in a first region 32a and a smaller opacity OPA% in a second region 32b. The first region 32a is located on and around the associated illumination center 22aa of the diffuser plate 27, and on and around the axis between the illumination window center 24a and the point center 15a. The second region 32b is located spaced apart from the associated illumination center 22aa of the diffuser plate 27, and spaced apart from the axis between the illumination window center 24a and the point center 15a. In the first embodiment, the region 32a with a larger opacity OPA% can itself have an unequal opacity OPA% in terms of its range, i.e., higher on and around the associated illumination center 22aa and smaller at locations spaced apart therefrom. In the second embodiment, the region 32a with a larger opacity OPA% can itself have a unique, identical opacity OPA%. Similarly, according to different possible embodiments, the region 32b with smaller opacity OPA% may itself have unequal opacities OPA% with respect to its extent, i.e., higher adjacent to the region 32a and smaller at a position spaced apart from this region 32a, or may have the same opacity OPA%. According to another embodiment, the high-opacity portion 25 has the same opacity OPA% throughout its entire extent, i.e., an area with one single opacity OPA%.

[0145] Similarly, the low-opacity portion 26 itself may have unequal opacity OPA% with respect to its extent, i.e., higher in an area 26a adjacent to the high-opacity portion 25 (and possibly area 32b), and lower in an area 26b spaced apart from the high-opacity portion 25 (and possibly area 32b). According to another embodiment, the low-opacity portion 26 has the same opacity OPA% throughout its entire extent, i.e., an area with a single opacity OPA%.

[0146] However, regardless of its implementation, the diffuser plate 27 has a high opacity OPA% in the area 32a on and around its associated illumination center 22aa, specifically, it is completely opaque, and has a low opacity OPA% in the area 26b opposite the area 32a and near the diffuser opening 30, specifically, it is completely transparent, and has a continuously decreasing opacity in the area from the high opacity OPA% area to the low opacity area. The opacity OPA% of the diffuser plate 27 varies continuously or discretely. Explicit reference Figure 9 、 10A to 10C and 11A to 11H, which illustrate different possible implementations and are not limiting.

[0147] According to one possible embodiment, the diffuser plate 27 may be made of a single plate. According to another embodiment, the diffuser plate 27 may comprise several portions of plates placed and fixed end to end. According to another embodiment, the diffuser plate 27 may comprise several portions of plates fixedly overlapped.

[0148] The diffuser plate 27 can be made of a plastic material filled with light-shielding pigments of the desired density to obtain the appropriate variation in opacity OPA%. According to another implementation, the diffuser plate 27 can include a transparent back surface on which is a fixed portion of a film or dots having a certain opacity to allow obtaining the appropriate variation in opacity OPA%. Figure 8A and 8E In the depicted implementation, the diffuser plate 27 comprises, on the front face 29a, a pattern of small protrusions 34 having a free end lateral surface on which are fixed small dots made of aluminum foil (or a composite containing aluminum) die-cut from an aluminum tape (or a composite containing aluminum) 35. The density of the pattern of protrusions (the number of identical protrusions or the surface of different protrusions) depends on the desired opacity OPA%: the higher the opacity OPA%, the higher the density. The aluminum tape (or the composite containing aluminum) is die-cut so as to cover only the free end lateral surfaces of the protrusions and not the spaces between the protrusions, leaving the remaining aluminum tape 36. In this way, the density of the dots made of aluminum foil (or a composite containing aluminum) allows to obtain an appropriate desired opacity OPA%. According to the accompanying drawings ( Figure 8B 、 8C and 8D), the diffuser plate 27 may have a rear face 29d having a small conical protrusion 33.

[0149] According to an unillustrated embodiment in which the diffuser plate 27 is located only on the illumination side 12a and not on the camera side 12d, the diffuser plate 27 is shorter, and its outer contour is generally a curved triangle. It may lack the diffuser opening 30 described above, which itself has a closed contour, but instead has a single notch to prevent the camera field of view 19 from being narrowed, cut off, or distorted. This notch is an opening that itself has an open contour. The term "diffuser opening 30" should be interpreted as also encompassing a notch that itself has an open contour.

[0150] According to a possible implementation, the weight of the mobile phone accessory 1 may be between 7.3 g and 10 g.

[0151] The present invention also relates to a method for implementing an apparatus 1+2 comprising a smartphone 2 and a mobile phone accessory 1 to measure the color of an AOI target. In this method, a material M having an area of ​​interest (AOI), a smartphone 2, and a mobile phone accessory 1 are provided. The smartphone 2 and mobile phone accessory 1 are then structurally associated with a removable connecting member 3 so that the camera window 20 of the mobile phone accessory 1 is coupled to the camera lens 9 of the smartphone 2, and the illumination window 24 or illumination area of ​​the mobile phone accessory 1 is coupled to the flash 10 of the smartphone 2. The material M and mobile phone accessory 1 are then applied to each other so that the material M is on the exterior 13b of the housing 11 and the AOI target is in front of the measurement aperture 16.

[0152] Next, smartphone 2 is instructed to use a flashlight and take a photo 36. This means that light is illuminated and reflected at the light incident point 15, that is, the AOI target, and the N color measurement targets 17. As previously described, due to the arrangement of illumination member 22, light scattering member 23, and camera field of view 19, photo 36 is a photograph of the illuminated AOI target and the N color measurement targets 17 under identical lighting conditions. Photo 36 is then processed using an appropriate processing program for measuring colors in the photo, comparing the captured color of the AOI target with the captured colors of the N color measurement targets 17 of the color measurement area unit 17a, to measure the colors of the AOI targets. This appropriate processing program for measuring colors in the photo can be a downloaded application loaded on smartphone 2, or smartphone 2 can be arranged to be transmitted to a different location or processing device, where the appropriate processing program for measuring colors in the photo is performed.

[0153] In a specific application, the method is performed by a person who wishes to measure the color of their skin. This application is not limiting. The method can be performed by other people, for personal or professional purposes, and the material M whose color we want to know may not be skin, but any other material M.

[0154] Figure 15 Shown in accordance with Figure 9 The arrangement is completed in the photo 36. This photo 36 is suitable for the color measurement process. The photo 36 includes two adjacent areas 37 and 38, which respectively show the AOI target and the N color measurement targets 17. Figure 15 The upper part of the diagram shows two gray blocks, which, from left to right, are the color values ​​of the brightest area of ​​the front wall and the darkest area of ​​the front wall. The closer these values ​​are, the more uniform the light incident points illuminating the measurement hole 16 and the color measurement area unit 17a are.

[0155] The measurement of the AOI target is expressed in LAB units, where L represents brightness, a represents green-red, and b represents yellow-blue.

Claims

1. A mobile phone accessory (1) adapted and intended to be functionally and structurally associated with a portable digital device (2), the portable digital device being capable of running a program for performing a function, and adapted and intended to be associated with an area of ​​interest (AOI) target of a material M, and comprising: a support and handling housing (11) having an opaque wall defining an interior space (11a) which is protected from external light when in use, the opaque wall having an inner face (13a) and including an aperture (16) suitable and intended for association with the material M and the AOI target and located within the light entry point (15), and a rear wall portion (14b), an illumination member (22) having an illumination axis (22a), arranged at least partially in said housing (11) and adapted and intended, in use, to generate light illuminating said light entry point (15), a camera field of view member (19) having a field of view axis (19a), arranged at least partially in said housing (11) and adapted and intended for taking a reflected photograph of said light entry point (15) and its contents, a diffuser plate (27) located within the housing (11), adapted and intended to be functionally associated with the illumination member (22) in use, having a diffuser opening (30) in which the camera field center (19aa) is at the intersection of the field of view axis (19a) and the illumination center (22aa) is at the intersection of the illumination axis (22a), and comprising a high-opacity portion located near the illumination member (22) and a low-opacity portion located at the periphery of the high-opacity portion, Its characteristics are: The housing (11) comprises a front wall portion (14a) extending towards and spaced apart from the rear wall portion (14b) and in which the hole (16), i.e. the measuring hole (16), is located. The outer surface (13b) of the front wall portion (14a) includes an area surrounding the measurement aperture (16), the area being suitable and intended to be in contact with the material M located externally around the AOI target and being suitable and intended to conceal any passage of external ambient light, The mobile phone accessory comprises N color measurement targets (17), which are located in the internal space (11a) and fixed on the inner surface (13a) of the front wall portion (14a) having the measurement hole (16) on the side, and together form a color measurement area unit (17a). the light entrance point (15) with the measurement aperture (16) and, when in use, with the AOI target and the N color measurement targets (17) located within the camera field of view member (19) is viewed through the scattering opening (30), The scattering plate (27) has a varying opacity, wherein a portion (25) or region (32a) on and around the illumination center (22aa) has high opacity, and a portion (26) or region (26b) opposite and near the scattering opening (30) has low opacity, and the opacity decreases continuously from the portion or region with high opacity to the portion or region with low opacity. The scattering plate (27) also makes the illumination within the range of the AOI target and the range of the N color measurement targets (17) uniform. Therefore, the mobile phone accessory (1) is suitable for and intended to allow photographs of the illuminated AOI target and the illuminated N color measurement targets (17) to be taken under the same uniform lighting conditions.

2. The mobile phone accessory (1) according to claim 1, characterized in that The high-opacity portion (25) and the low-opacity portion (26) have unequal opacities in terms of their ranges, the scattering plate (27) has high opacity in the area (32a) on and around the illumination center (22aa), has low opacity in the area (26b) opposite to the area (32b) and near the scattering opening (30), and has continuously decreasing opacity in the area from the high-opacity area to the low-opacity area.

3. The mobile phone accessory (1) according to any one of claims 1 and 2, characterized in that The opacity of the scattering plate (27) varies continuously or discretely.

4. The mobile phone accessory (1) according to any one of claims 1 to 3, characterized in that The opacity of the high-opacity portion (25) or the region (32a) thereof is greater than the opacity of the low-opacity portion (26) or the region (26b) thereof, that is, greater than 70%.

5. The mobile phone accessory (1) according to any one of claims 1 to 3, characterized in that The opacity of the low-opacity portion (26) or the region (26b) thereof is less than the opacity of the high-opacity portion (25) or the region (32a) thereof, that is, less than 70%.

6. The mobile phone accessory (1) according to any one of claims 1 to 3, characterized in that The opacity of the scattering plate (27) varies from completely opaque to completely transparent.

7. The mobile phone accessory (1) according to any one of claims 1 to 3, characterized in that The diffusion plate (27) is made of a plastic material filled with light-shielding pigments of a desired density to obtain appropriate opacity variations.

8. The mobile phone accessory (1) according to any one of claims 1 to 3, characterized in that The scattering plate (27) comprises a transparent back surface on which is a fixed portion of film or dots with a certain opacity to allow obtaining an appropriate opacity variation.

9. The mobile phone accessory (1) according to claim 8, characterized in that The scattering means alternates high opacity sections with low opacity sections in order to create an opacity that is averaged between them.

10. The mobile phone accessory (1) according to any one of claims 1 to 3, wherein the mobile phone accessory does not contain a light source inside, but the lighting member (22) is associated with a light source outside the accessory (1).

11. A mobile phone accessory (1) according to any one of claims 1 to 3, wherein the camera field of view member (19) includes a camera window (20), the camera window being located within the rear wall portion (14b) adapted and intended to pass through the field of view of a camera external to the accessory (1), the mobile phone accessory (1) being characterized in that it does not contain a camera internally.

12. The mobile phone accessory (1) according to any one of claims 1 to 3, characterized in that The camera field of view member (19) includes a lens (21) so as to have a semi-focus on the center of the AOI target.

13. The mobile phone accessory (1) according to any one of claims 1 to 3, characterized in that N suitable color measurement targets (17) sufficient to allow accurate measurement of the color of the AOI target are selected to have defined colors within a narrow color gamut representing the entire AOI target color range, the color measurement targets collectively forming a color measurement area unit (17a), whereby the mobile phone accessory (1) is suitable and intended to measure the color of the AOI target by allowing photographs of the illuminated AOI target and the N illuminated color measurement targets (17) to be taken under the same lighting conditions, processing such photographs to compare the color of the photographed AOI target with the color of the photographed color measurement targets (17) of the color measurement area unit (17a) in order to measure the color of the AOI target.

14. The mobile phone accessory (1) according to any one of claims 1 to 3, characterized in that The color measurement targets (17) are arranged side by side along at least one line of the color measurement area unit (17a), and the color measurement targets (17) belonging to two consecutive lines are arranged side by side.

15. The mobile phone accessory (1) according to any one of claims 1 to 3, characterized in that The radius of the color measurement area unit (17a) is firstly smaller than 4 times the radius of the measurement hole (16), and secondly larger than 2 times the radius of the measurement hole (16).

16. The mobile phone accessory (1) according to any one of claims 1 to 3, characterized in that The number N of the color measurement targets (17) sufficient to allow accurate measurement of the color of the AOI target is less than 50.

17. The mobile phone accessory (1) according to any one of claims 1 to 3, characterized in that A color measurement target (17) is in the form of a dot and has a width of less than 1 cm.

18. The mobile phone accessory (1) according to any one of claims 1 to 3, characterized in that A method for realizing the color measurement area unit (17a) of the N color measurement targets (17), the method comprising the following steps: Make available a large number of several basic color materials, from which a certain proportion of the basic color materials can be extracted, making available a substrate (18), which is the housing (11) or a separate substrate which is subsequently fixed to the housing (11), preparing N portions of fine color materials from the basic color materials by mixing sufficient proportions of the identified basic color materials so that the color of each portion of the fine color material is completely consistent with the color of the intended color measurement target, Sampling a small amount of fine color material from each of the N portions to obtain N available samples of the small amount of fine color material, depositing N fine color material samples onto the substrate (18) in a suitable order and arrangement so as to form the color measurement area units (17a) of the N color measurement targets (17), The device includes a number N of color measurement targets (17) in a narrow color gamut, N being at least 20 and less than 30, each color measurement target (17) being in the shape of a dot, having a radius less than 1 cm and a volume of 13 to 15 N color measurement targets (17) together form a color measurement area unit (17a), the color measurement area unit (17a) is fixed on the inner surface (13a) of the front wall portion (14a), is placed within the position of the light incident point (15), and is adjacent to, close to, and around the measurement hole (16), the N color measurement targets (17) are arranged side by side along at least one line of the color measurement area unit (17a), and the color measurement area unit is annular and centered on the point center (15a).

19. An apparatus for measuring the color of an AOI target as an area of ​​interest of a material M, said measurement being performed relative to appropriate N color measurement targets (17) having defined colors within a narrow color gamut representing the entire AOI target color range, by performing illumination and light reflection on said AOI target and said N color measurement targets (17) and photographs of the illuminated AOI target and the illuminated color measurement target (17) under the same uniform lighting conditions, processing such photographs to compare the color of the photographed AOI target with the color of the photographed color measurement target (17) of the color measurement area unit (17a) so as to measure the color of said AOI target, said apparatus comprising: a smartphone (2) capable of running a program for performing the function, having a camera and a flash and an appropriate processing program for measuring the colors in the photograph, A mobile phone accessory (1) according to any one of claims 1 to 18, and A removable connecting member (3) is used to fix the mobile phone accessory (1) to the smart phone.

20. The device for measuring AOI target color according to claim 19, wherein: The light for illuminating the AOI target and the N color measurement targets (17) is a flash of the smartphone (2), The camera that takes the picture of the illuminated AOI target and the N color measurement targets (17) is the camera of the smartphone (2), The arrangement of the mobile phone accessory (1) allows the light beam generated by the flash of the smartphone (2) and allows the field of view of the camera of the smartphone (2) to pass through, An appropriate processing program for measuring the colors in the photograph is loaded in the smartphone (2) rather than in the mobile phone accessory (1).

21. A method for measuring the color of an AOI target as an area of ​​interest of a material M, characterized in that: making available a material M, an area of ​​interest AOI containing such material, Making available a smartphone (2) capable of running a program for performing the function, having a camera and a flash, and loaded with a suitable processing program for measuring the colors in the photograph, making available a mobile phone accessory (1) according to any one of claims 1 to 18, The smartphone (2) and the mobile phone accessory (1) are structurally associated by means of a removable connecting member (3), The material M and the mobile phone accessory (1) are applied to each other so that the material M is located on the outer surface (13b) of the housing (11) and the AOI target is located in front of the measuring hole (16), commanding the smartphone (2) to use a flashlight and a photo to illuminate and reflect light on the AOI target and the color measurement target and the photo of the illuminated AOI target and the color measurement target under the same uniform lighting conditions, And using the appropriate processing program for measuring color in the photograph, the photograph is processed to measure the color of the AOI target.

22. The method according to claim 21, characterized in that The material M is human skin, and the color of the skin is measured.

Images