System and method for inspecting chromaticity uniformity of multiple portions of object

Abstract

A system (10) and a method are provided, the method comprising the steps of S1) illuminating a portion (Aj) of an object (A) by a light beam having a selective respective illumination wavelength ([lambda] i) under respective illumination conditions; s2) acquiring a corresponding monochromatic digital image () representing the portion (Aj) under a corresponding illumination condition; s3) repeating steps S1 and S2 for a plurality of predetermined irradiation conditions () and for each portion (Aj) whose chromaticity uniformity needs to be compared; s4) calculating, for each monochromatic digital image (), a respective luminous intensity value () representing the luminous intensity reflected by the portion Aj under the respective illumination conditions; s5) for each combination () comprising a first portion (Ah) and a second portion (Ak) of the object (A), calculating, from a mathematical model (M) as a function of the luminous intensity value (), respective chromaticity contrast values representing the chromaticity uniformity of these portions (Ah, Ak), and S6) outputting uniformity data (D) representing the chromaticity uniformity of the portions (A1,..., Aj,..., Am) from the chromaticity contrast values ().

Description

Technical Field

[0001] This invention relates to a system and method for checking the color uniformity of multiple parts of an object. Technical Background

[0002] In the manufacturing industry, it is generally important that manufactured goods intended for sale possess homogeneous characteristics throughout the entire production process and for all customer orders. In particular, it is desirable for the aesthetic characteristics of manufactured goods to remain as consistent as possible.

[0003] In particular, but not limited to, color uniformity between multiple parts of an object is crucial in the textile industry.

[0004] Traditionally, the color uniformity of an object is checked by visually inspecting fabric samples.

[0005] Before visual inspection, a piece of material is physically cut (usually called a "cut-length," typically 20 cm x 150 cm). The cut-length is then prepared by bringing disparate fabric areas closer together to obtain an actual fabric sample to be inspected. The visual inspection is then performed by a trained operator who visually assesses the color uniformity of the fabric sample.

[0006] However, visual inspection of fabric samples has some drawbacks.

[0007] One of the most significant drawbacks is that the evaluation results are subjective and operator-dependent, and the same operator's judgment may vary on different dates or at different times of the day. Furthermore, preparing fabric samples is time-consuming. Additionally, material waste occurs when cutting fabric pieces for use as samples. The operator also spends considerable time performing visual inspections and completing decision-making processes to determine whether the fabric sample has the desired level of color uniformity.

[0008] In addition to the visual inspection mentioned above, systems and methods for measuring color, particularly by means of a spectrophotometer, are also known in the textile industry.

[0009] However, such systems and methods also have some drawbacks.

[0010] One drawback is that, due to the technology employed, the area defined by the spectrophotometer is extremely small (typically no more than 30 mm in diameter). Another drawback is that the spectrophotometer is only effective on solid-color fabrics, as the presence of any pattern will produce different results depending on the defined area. Yet another drawback is that the spectrophotometer is difficult to use for testing "fluffy" fabrics (such as wool, cashmere, etc.) because its working principle is based on the angle of light incidence on the fabric.

[0011] Examples of such systems and methods using spectrophotometers can be found in patent publication text DE 101 02 607A1. In that patent publication text, in order to examine the color of fabrics and similar materials, a data processing unit compares a digitized image obtained from a standard model with an image acquired from a test fabric.

[0012] However, this example also has some drawbacks that need improvement. According to the patent publication text DE 101 02 607 A1, one drawback is that a white calibration must be performed (usually at the beginning of each day or at some point during the day) in order to always be able to reference the standard "baseline" conditions.

[0013] Another drawback is that, in the system described in the patent publication DE 101 02 607 A1, the observed object must be laid flat, and different color regions need to be analyzed differently by physically separating the areas of the image. This deviates from the analogy principle of human visual inspection (which does not distinguish between parts).

[0014] US 2013 / 293702 A1 describes a multispectral imaging color measurement system, comprising a darkroom, a sample platform, and an imaging device for capturing the object under test; a controllable illumination device, a filter wheel unit, an imaging signal processing unit, and an electronic control unit. A method for processing the imaging signal of the multispectral imaging color measurement is also proposed.

[0015] US 9,838,612 B2 describes an inspection apparatus for inspecting a target. The apparatus includes a monochrome image retrieval module, an illumination module, and a control module. The monochrome image retrieval module is positioned above the target, with its optical axis facing the target. Each illumination module includes a light-emitting element of a different color. The control module controls the illumination modules to sequentially generate illumination light in sequence according to different colors and different incident angles, and further controls the monochrome image retrieval module to sequentially retrieve monochrome images, each monochrome image responding to one illumination by the illumination light. The control module inspects the target based on the monochrome images. Summary of the Invention

[0016] One object of the present invention is to provide a system and method that can overcome some of the shortcomings of the prior art.

[0017] According to the present invention, this and other objectives are achieved by systems and methods having the technical features described in the appended independent claims.

[0018] In particular, compared to the aforementioned visual inspection, the present invention provides a system and method for ensuring the repeatability of inspection results when checking the color uniformity of multiple parts of an object, even under different times and operating conditions. The time required for the operator to complete the inspection is also significantly reduced. Furthermore, especially when checking the color uniformity of textile objects, it is no longer necessary to physically cut the material to create so-called "pieces." Finally, more in-depth process data is obtained, which can be stored through an information technology system.

[0019] Furthermore, compared to colorimetric uniformity checks (especially those performed using a spectrophotometer), this invention provides a system and method in which the defined area to be checked can be limited to the desired size (while spectrophotometers are limited to very small sizes due to the technology employed). Moreover, the system and method according to the invention perform color-independent measurements based on luminescence intensity, thus being effective even in the presence of patterns. Furthermore, unlike solutions using spectrophotometers, the system and method of the invention do not present difficulties in checking the colorimetric uniformity of "hairy" fabrics (e.g., wool, cashmere, etc.) because the type of illumination and image acquisition is not significantly affected by the angle of incidence of light on the object under test.

[0020] According to an advantageous aspect of the invention, the system and method avoid the need for continuous and frequent calibration, since periodic verification (e.g., once a month) is sufficient to ensure the repeatability of measurement results over time (keeping the object as a reference standard).

[0021] It should be understood that the appended claims are a key component of the technical teachings provided in the following detailed description of the invention. Specifically, the appended dependent claims define some preferred embodiments of the invention, which include some optional technical features.

[0022] Further features and advantages of the invention will become apparent from the following detailed description, which is provided by way of non-limiting example only, and in particular with reference to the accompanying drawings outlined below. Attached Figure Description

[0023] Figure 1 This is a perspective view of a system for checking the color uniformity of multiple parts of an object. The system was manufactured according to an exemplary embodiment of the present invention.

[0024] Figure 2 and Figure 3 yes Figure 1 The front and side views of the system are shown.

[0025] Figure 4 The irradiation device shown in the foregoing figures is similar to that of the system shown in the foregoing figures. Figure 2Front view. (And) Figure 2 The difference is, Figure 4 The light source constituting the irradiation device is shown.

[0026] Figure 5 The irradiation device shown in the foregoing figures is similar to that of the system shown in the foregoing figures. Figure 3 A side view. Specifically, Figure 5 The light source of the irradiation device and the light radiation emitted by the light source are described.

[0027] Figure 6 This is a cross-sectional side view illustrating exemplary and preferred applications of the system shown in the foregoing figures in the textile industry.

[0028] Figure 7 This is a functional block diagram of the system shown in the aforementioned figures.

[0029] Figure 8 This is a schematic flowchart illustrating a series of steps in a method for checking the color uniformity of multiple parts of an object. The method is implemented according to an exemplary embodiment of the present invention and can be used in the system shown in the foregoing figures.

[0030] Figure 9 yes Figure 6 The system shown is applied to the textile industry. (Front-view perspective)

[0031] Figure 10 It is a fabric (whose color uniformity is determined by...) Figure 6 and Figure 9 The diagram shows a system for inspection.

[0032] For completeness, the following is a list of alphanumeric labels (figure reference numerals) and names used in this document to identify the parts, elements and components shown in the figures outlined above.

[0033] Object A1, …, A j , …, A m Parts of the object Reserved location Irradiation axis Y, optical axis Z, fixed axis W, transverse axis d 12 Irradiation distance d16 detection distance

[0034] Irradiation conditions

[0035] Irradiation wavelength

[0036] Mathematical Model of Monochrome Digital Image M Luminous intensity value section combination

[0037] Poor luminous intensity Chromaticity contrast value S, threshold D, uniformity data 10, system 12, irradiation equipment 14 16 Light source; 18 Image acquisition device; 20 Support structure; 22 Bracket; 24 Frame; 26 Base plate; 28 Lateral arm; 100 Control unit; 102 Housing; Window Detailed Implementation

[0038] refer to Figures 1 to 4 The diagram illustrates a system manufactured according to an exemplary embodiment of the present invention, the system being generally designated as 10.

[0039] System 10 is configured to inspect multiple parts A1, …, A of object A. j , …, A m The system 10 is particularly suitable for use in the textile industry, as will become apparent from the detailed embodiments described below. For example, the system can be used to check the color uniformity of fabric strips. However, the use of the system 10 should not be limited to the textile industry. As will be apparent to those skilled in the art, the system 10 can be applied to any manufacturing sector. As a non-limiting example, in addition to the textile industry, the system and related methods are also applied to the food, clothing, printing, plastics, paper, wood, leather, packaging, and cosmetics sectors, and more broadly to any sector where color inspection is important.

[0040] exist Figure 1 In the diagram, object A, whose color uniformity is to be checked, is shown schematically, for example, as a structure with the shape of a thin parallelepiped. Of course, Figure 1 The shape of object A shown should not be intended to limit the objects whose chromaticity uniformity can be checked using the system 10 of the present invention.

[0041] For details, please refer to the following: Figures 1 to 4 The system 10 includes a multispectral irradiation device 12, which is configured to continuously emit light of wavelengths toward an object A whose color uniformity needs to be checked. A light beam, the wavelength of which is selected from multiple predetermined wavelengths. The irradiation is selectively chosen. More specifically, the irradiation device 12 is configured to present multiple irradiation conditions. Under each irradiation condition Below, the irradiation device 12 emits light with a corresponding irradiation wavelength toward object A. A beam of light, the illumination wavelength of which is selected from n predetermined illumination wavelengths that are different from each other. Choose from.

[0042] In the illustrated embodiment, the irradiation device 12 sequentially includes a plurality of light sources. Each light source They are all configured to emit light radiation toward the object A to be inspected in order to irradiate it.

[0043] In this article, please refer to Figure 4 In the embodiment shown, n light sources These are multiple LEDs included in the irradiation device 12.

[0044] Special Reference Figure 5 Each light source They all have irradiation axes This illumination axis defines the primary direction in which the associated light radiation propagates toward object A. Specifically, Figure 5 A light beam emitted by an LED is shown; in the illustrated embodiment, the light beam is emitted by a corresponding light source. The emitted radiation. From Figure 5 It can be inferred that each light source The illumination axes all converge towards the optical axis Y. For example, the light source Irradiation axis They can converge toward a common point (not shown) located along the optical axis Y of the image acquisition device 16, which will be described in more detail below.

[0045] Under each irradiation condition Below, each light source Configured to be selectively activated—different from the other n-1 light sources. —so that the emission has a corresponding predetermined wavelength The corresponding light radiation, whose wavelength differs from that of the other n-1 light sources. The emitted light radiation has n-1 wavelengths .

[0046] As will be obvious to those skilled in the art, the light source The quantity n can be selected based on the object A to be inspected, and can be adjusted as needed in any case. The wavelength can be selected across the entire emission spectrum (even beyond the visible spectrum, i.e., ultraviolet or infrared). As a non-limiting example, n can be 8.

[0047] As described above, in the illustrated embodiment, the light source It is an LED device.

[0048] As previously mentioned, system 10 also includes a monochrome image acquisition device 16, which is configured to acquire multiple monochrome digital images. When the aforementioned part A j Under the corresponding irradiation conditions When illuminated by the illumination device 12, each monochrome image This represents the m parts A1, …, A of object A. j , …, A m The corresponding part A that needs to be checked for color uniformity. j In other words, object A has m parts A1, …, A2. j , …, A m Obtain the corresponding monochrome digital images of these parts. For each part A j Obtain the corresponding irradiation conditions n images Therefore, the acquired monochrome digital image The total number is n×m.

[0049] More specifically, the image acquisition device 16 includes an optical sensor (e.g., a CCD or CMOS sensor) configured to capture images under each illumination condition. Each part A of object A when irradiated by the irradiation device 12 j The optical image is converted into the corresponding monochrome digital image. .

[0050] Preferably, the image acquisition device 16 is a camera or video camera.

[0051] Image acquisition device 16 has an optical axis Y, which indicates when part A of object A... j When the irradiated device 12 illuminates the light beam reflected from it, it will enter substantially perpendicularly into the direction of the focal plane of the optical sensor included in the image acquisition device 16.

[0052] In the illustrated embodiment, each monochrome digital image It is a bitmap image, which consists of a matrix of points (or pixels) in a manner known per se, where each point is represented according to a scale (or level) or grayscale definition of shading that varies from white to black. Specifically, the value associated with each point corresponds to the intensity of the shading within the grayscale range. As a non-limiting example, the acquired image may have a resolution of 2 MP (1600 × 1200 pixels).

[0053] In the illustrated embodiment, the illumination device 12 is located around the optical axis Y defined by the image acquisition device 16. Specifically, the relative positioning of the illumination device 12 and the image acquisition device 16 makes the light source... Around the optical axis Y. More specifically, the light source Arranged circumferentially around the optical axis Y, preferably equidistant from each other at an angle.

[0054] refer to Figure 6The preferred application of system 10 in the textile industry is shown by way of non-limiting example only. In particular, in this application, system 10 is configured to check the color uniformity of a fabric, in this case, the fabric representing object A.

[0055] exist Figure 6 In the illustrated embodiment, system 10 is mounted within a generally box-shaped housing 100. Housing 100 has a window 102 through which the fabric (i.e., object A) faces system 10. Therefore, illumination device 12 can illuminate the fabric through window 102, and image acquisition device 16 can acquire monochrome digital images through window 102. .

[0056] In particular, when illuminated Figure 6 When referring to the fabric of object A, the irradiation device 12 and parts A1, …, A of object A are irradiated. j A m The irradiation distance d between 12 Under different irradiation conditions The value remains essentially constant. Similarly, when acquiring images representing fabrics, the image acquisition device 16 and the portions A1, …, A of object A are... j , …, A m The detection distance d between 16 Acquiring different monochrome digital images It remained essentially constant during this period. More specifically, in Figure 6 In an exemplary embodiment, the illumination distance d 12 It is considered to be along a path substantially perpendicular to the preferably constituting light source 141,…, 14 n The distance d is the distance along a straight line in the plane where the LED is located (specifically, the straight line is substantially parallel to the optical axis Y), while the detection distance d is... 16 It is considered to be the distance along a straight line coinciding with the optical axis Y.

[0057] In the illustrated embodiment, system 10 includes a support structure 18 that supports the irradiation device 12 and the image acquisition device 16, specifically supporting the irradiation device 12 and the image acquisition device 16 in the aforementioned relative positions.

[0058] In the illustrated embodiment, the support structure 18 includes a bracket 20 configured to support the image acquisition device 16. Furthermore, the support structure 18 includes a frame 22 connected to the bracket 20, and the frame 22 has an illumination device 12 located on its surface, intended to face the object A whose color uniformity needs to be checked. Specifically, the light source 14 is carried by the bracket 20. The frame 22 conveniently has an annular or circumferential shape, particularly an annular or circumferential shape centered on the optical axis Y. Optionally, as... Figure 1 and Figure 2 As shown, frame 22 is mounted on bracket 20 at a fixed axis Z. The fixed axis Z is substantially perpendicular to the optical axis Y. More specifically, the fixed axis Z is radially positioned relative to frame 22.

[0059] Advantageously, but not necessarily, the support body 20 includes a substrate 24 on which the image acquisition device 16 is mounted. In addition, the support body 20 includes a pair of transverse arms 26 connected to the frame 22, particularly on the transverse or radially opposite sides of the optical axis Y.

[0060] like Figure 6 As shown, system 10 is assembled by fixing bracket 20 to the inner wall of housing 100.

[0061] Special Reference Figure 7 The figure shows a functional block diagram of the system shown in the foregoing figures. In this functional block diagram, the system 10 also includes a control unit 28 coupled to the illumination device 12 and the image acquisition device 16.

[0062] In the illustrated embodiment, the control unit 28 is configured to sequentially place the irradiation device 12 under each irradiation condition. Therefore, the control unit 28 drives the irradiation device 12 to sequentially present all irradiation conditions. .

[0063] In the illustrated embodiment, the control unit 28 is configured to in each irradiation condition The following selectively activates only one corresponding light source 14; in particular, as previously stated, the remaining n-1 light sources... It will remain closed. In this way, the irradiation device 12 can emit light with a light source. corresponding wavelength The light beam, the wavelength of which is from the predetermined illumination wavelength Selected from [the list].

[0064] Control unit 28 is also configured to drive image acquisition device 16 in order to provide n corresponding illumination conditions presented by illumination device 12. The following data is collected to represent m parts A1, …, A of object A. j , …, A m Multiple monochrome digital images As described above, the control unit 28 commands the image acquisition device 16 to acquire each monochrome digital image. The monochrome digital image represents the corresponding illumination conditions presented by the illumination device 12. The corresponding part A of object A below j In other words, for each part A of object A... j and in each irradiation condition Below, whenever part A of object A... j The irradiated device 12 emits light corresponding to the irradiation conditions. corresponding wavelength When illuminated by a beam of light, the image acquisition device 16 is activated to obtain a corresponding monochrome digital image. .

[0065] The control unit 28 is also configured to receive multiple monochrome digital images acquired by the image acquisition device 16. As input.

[0066] In addition, the control unit 28 is configured to calculate multiple luminous intensity values. , where each luminous intensity value It is for the corresponding monochrome digital image Calculated and expressed under the corresponding irradiation conditions. Below, part A of object A j The intensity of light reflected towards the image acquisition device 16.

[0067] As a non-limiting example only, each luminous intensity value It can be calculated as a corresponding monochrome digital image. The mathematical model M is a linear function of the numerical value associated with each monochrome pixel. Specifically, each pixel can be associated with a corresponding numerical value, for example, in the range of 0 to 255 (when considering 8-bit channels), which identifies a specific grayscale shading. More specifically, the mathematical model M can advantageously assign each luminous intensity value... The calculation is a weighted sum, for example, with the sum that constitutes the corresponding monochrome digital image. The average value associated with each monochrome pixel. More specifically, each luminous intensity value... The range can be from 0 to 255.

[0068] Subsequently, for the parts A1, …, A from object A h , …, A k , …, A m The set obtained includes the first part A. h And different from Part A h Part A k Each combination The control unit 28 is configured to calculate the chromaticity contrast value according to the mathematical model M. For example, through statistical regression (e.g., linear regression).

[0069] In the exemplary embodiments described herein, based on the mathematical model M, and the corresponding combinations Each associated chromaticity contrast value Based on multiple luminous intensity differences To determine, the plurality of luminous intensity differences include:

[0070]

[0071] In short, for each combination Calculate the differences in luminous intensity of n light sources. Among them, each luminous intensity difference It is for the corresponding irradiation conditions Calculated between the following two:

[0072] - Part A h Luminous intensity value and

[0073] Part Two A k Luminous intensity value .

[0074] In the illustrated embodiment, the control unit 28 is configured to target each combination Each obtained chromaticity contrast value Compare with the corresponding predetermined threshold S.

[0075] Finally, the control unit 28 is configured to output uniformity data D representing the chromaticity uniformity of object A, which is based on the combination of chromaticity contrast value Obtained. According to a preferred example of the invention, if for the combination At least one of them, the corresponding chromaticity contrast value If the uniformity data is greater than a predetermined threshold S, then the uniformity data D will indicate that object A should be considered "unqualified". Figure 7 (KO in the example). Conversely, according to the same example, if for all combinations... Each chromaticity contrast value If all values ​​are less than or equal to the predetermined threshold S, then the uniformity data D will indicate that the object A should be considered "qualified" ("OK" in the figure).

[0076] Special Reference Figure 8 A flowchart illustrating a method according to an exemplary embodiment of the present invention is shown. The method aims to examine multiple parts A1, …, A2 of an object A. j , …, A m The color uniformity, and particularly but not exclusively, this method can be derived from... Figure 1 and Figure 6 The system shown is executed as described. As will be apparent to those skilled in the art, the method can also be implemented by different systems.

[0077] The method includes the following steps S1 to S6.

[0078] In step S1, under the corresponding irradiation conditions Below, at least a part of object A, A j Selectively possessing corresponding irradiation wavelengths The beam of light shone on it.

[0079] In step S2, the corresponding monochrome digital image is acquired. This monochrome digital image represents the image under the corresponding illumination conditions. The corresponding part A of the irradiated object A j .

[0080] In step S3, for multiple predetermined irradiation conditions And for each part A of object A that needs to have its color uniformity checked. j Repeat steps S1 and S2. Under each irradiation condition... Below, the light beam illuminates from multiple predetermined wavelengths that are different from each other. Select the corresponding irradiation wavelength Illuminate object A.

[0081] In step S4, for each monochrome digital image Calculate the corresponding luminous intensity value This luminous intensity value represents the luminous intensity under the corresponding irradiation conditions. The following is a corresponding part A of object A j The intensity of reflected light.

[0082] In step S5, for the portion A1, …, A from object A… h , …, A k , …, A m The first part A obtained from the set h And different from Part A h Part A k Each combination According to the m × n luminous intensity value ( The mathematical model (M) of at least a subset of the functions of ) is computed to represent the combination. Color contrast value of color uniformity Specifically, the mathematical model M will be based on the first part A. h Part A k Calculated 2×n luminous intensity values To calculate each chromaticity contrast value More specifically, and as illustrated in the previous examples in this paper, according to the mathematical model M, with the corresponding combination Each associated chromaticity contrast value Based on multiple luminous intensity differences The determination of each luminous intensity difference It is for the corresponding irradiation conditions Calculated between the following two:

[0083] - Part A h Luminous intensity value and

[0084] Part Two A k Luminous intensity value .

[0085] In step S6, based on the chromaticity contrast value Each output represents a part A1, ... A of object A. j A m The uniformity data D of the color uniformity.

[0086] Preferably, in step S3, each luminous intensity value Calculated as corresponding monochrome digital image I i A linear function of the numerical value associated with each monochrome pixel.

[0087] Preferably, in step S6, each chromaticity contrast value is... Compare with the corresponding predetermined threshold S.

[0088] Preferably, in step S5, when for at least one combination The corresponding chromaticity contrast value When the uniformity data is higher than the predetermined threshold S, the uniformity data D indicates that object A is unqualified. Figure 7 (KO in the middle).

[0089] Preferably, in step S5, when for all combinations Each chromaticity contrast value When all values ​​are less than or equal to the predetermined threshold S, the uniformity data D indicates that object A is qualified. Figure 7 OK in the middle).

[0090] For completeness, the following text will refer to Figure 6 , Figure 9 and Figure 10 An example of a preferred application of the invention is described, particularly in the textile industry.

[0091] Suppose we apply the system and method to multiple parts A1, …, A of a fabric. j , …, A mIn this application, "fabric" represents an object whose color uniformity needs to be checked. As will be described in more detail below, in this example, the number of portions, m, is 4.

[0092] In this exemplary application, the fabric is wound around and tensioned on a tensioning roller, and the system 10 faces the fabric strip. Specifically, the system 10 is included within a housing 100 and faces the fabric strip through a window 102.

[0093] In this application, as an example, a light source is formed. The number of LEDs, n, is assumed to be 8, and the number of wavelengths is also assumed to be 8.

[0094] System 10 also includes a motor (not shown) configured to move the illumination device 12 and the associated image acquisition device 16 (which are integrally connected via, for example, a support structure 18) in a direction W transverse to the optical axis Y. The transverse direction W corresponds to the length direction of the fabric strip, and the movement of devices 12, 16 corresponds to their translation in the transverse direction W.

[0095] In the application example shown herein, a guide structure 104 is present, on which the system 10 is guidedly mounted. The guide structure 104 is essentially a track, to which the system 10 is slidably coupled in a manner known per se. In particular, the slid coupling occurs between the support structure 18 and the track constituting the guide structure 104. In the application example shown, the guide structure 104 is supported within a housing 100; specifically, the ends of the guide structure 104 are fixed to the laterally opposite inner sides of the housing 100.

[0096] In the application example shown, the control unit 28 is also configured to control the motor to sequentially move the entire assembly including devices 12 and 16 in the lateral direction W and move it to a plurality of m predetermined positions. At each designated location In the middle, the image acquisition device 16 is directed toward different parts A of the fabric (i.e., the object A whose color uniformity needs to be checked). j .

[0097] In the application examples shown, please refer to the following: Figure 10 Part of A1, …, A j , …, A m and the corresponding reserved locations The quantity m is 4. Specifically, the first position Corresponding to the left edge portion A1, the second position Corresponding to the left center part A2, the third position Corresponding to the right center part A3, the fourth position This corresponds to the right edge portion A4.

[0098] In the application example shown, whenever system 10 is moved to each predetermined position by the motor according to the command of control unit 28... Repeat steps S1, S2, and S3 above. For each predetermined position... This leads to [the following] under irradiation conditions Below, at each predetermined location Facing the fabric portion A of system 10 j n monochrome digital images Collected.

[0099] More specifically, in the first position In the middle, under different irradiation conditions Below, the first set of monochrome digital images is acquired at point A1 on the left side of the woven edge. In the second position In the middle, under different irradiation conditions Below, the second set of monochrome digital images is acquired at point A2 in the center of the left side. In the third position In the middle, under different irradiation conditions Below, multiple monochrome digital images were acquired at point A3 in the center of the right side. Finally, in the fourth position. In the middle, under different irradiation conditions Below, multiple monochrome digital images were captured at point A4 on the right side of the woven edge. .

[0100] In the application example shown, in step S4, for the 32 previously acquired monochrome digital images... Calculate 32 corresponding luminous intensity values .

[0101] Now let's consider the first part A. h Part A k combination Where, for example, h=2 and k=3. This applies to such combinations involving the left central portion A2 and the right central portion A3. Calculate the luminous intensity differences of multiple n=8 values, where each luminous intensity difference is calculated using the formula... Confirmed. Specifically:

[0102]

[0103] Subsequently, regarding the combination Determine the appropriate chromaticity contrast value This chromaticity contrast value is based on the difference in luminous intensity previously obtained using the formula described above. It is used for calculations.

[0104] Then, for parts A1, …, A h , …, A k , …, A m All possible combinations (Where h≠k) Repeat the above steps to obtain multiple corresponding chromaticity contrast values. In this case, for parts A1, A2, A3, A4, there are 6 possible combinations, namely... This corresponds to 6 chromaticity pairs, i.e. .

[0105] Finally, each chromaticity contrast value calculated in this way... Compare with a predetermined threshold S.

[0106] If for at least one combination The corresponding chromaticity contrast value If the value is above the threshold S, uniformity data D will be output, which will indicate that object A is non-compliant (KO).

[0107] Conversely, if for all combinations Each chromaticity contrast value If all values ​​are less than or equal to the predetermined threshold S, then the uniformity data D will indicate that object A is qualified (OK).

[0108] Of course, without departing from the principles of the invention, the implementation methods and details can be widely changed relative to the content described and illustrated herein by way of non-limiting example only, without departing from the scope of protection of the invention as defined by the appended claims.

Claims

1. A method for inspecting multiple parts (A1, …, A2) of an object (A). j , …, A m A system (10) for color uniformity; the system includes: - Irradiation equipment (12). - Image acquisition device (16), and - Control unit (28), which is coupled to the image acquisition device (16) and the illumination device (12); The irradiation device (12) is a multispectral irradiation device; The image acquisition device (16) is a monochrome image acquisition device and is configured to acquire multiple monochrome digital images. ), where each monochrome digital image ( ) represents the corresponding part (A) of the object (A) irradiated by the irradiation device (12). j ); The irradiation device (12) is characterized in that it is configured to present multiple irradiation conditions. ), where, under each irradiation condition Below, the irradiation device (12) is directed toward the portion (A1, …, A). j , …, A m At least one of the emission wavelengths has a predetermined illumination wavelength that is different from each other. The corresponding irradiation wavelength (λ) selected in ) i () beam of light; Each monochrome digital image The corresponding irradiation conditions of the irradiation device (12) ) related; and The control unit (28) is configured to perform the following steps: S4) For each monochrome digital image Calculate the corresponding luminous intensity value ( The corresponding luminous intensity value represents the luminous intensity value under the corresponding irradiation conditions ( Under, by the corresponding part (A) of the object (A) j The intensity of light reflected towards the image acquisition device (16); S5) For the portion (A1, …, A) including the object (A). j , …, A m The first part (A) h ) and different from the first part (A) h Part Two (A) k Each combination of ) According to the luminous intensity value ( A mathematical model (M) of at least a part of a function of ), calculating the representation of the first part (A) h ) and the second part (A) k The corresponding chromaticity contrast value of chromaticity uniformity between ) );as well as S6) Based on the chromaticity contrast value ( The output represents the portion (A1, …, A1) of the object (A). j , …,A m The uniformity data (D) of chromaticity uniformity.

2. The system according to claim 1, wherein, The irradiation device (12) includes multiple light sources ( ).

3. The system according to claim 2, wherein, Each light source ( () is LED.

4. The system according to claim 2 or 3, wherein, Each light source ( ) is configured to emit only a corresponding predetermined illumination wavelength (λ) toward the object (A). i ( ) light radiation.

5. The system according to claim 4, wherein, Each light source ( ) has an irradiation axis ( The irradiation axis defines the main propagation direction of the light radiation emitted toward the object (A).

6. The system according to claim 5, wherein, The light source ( ) optical axis ( They converge toward the common point.

7. The system according to any one of claims 2 to 6, wherein, The light source ( The optical axis (Y) is defined by the image acquisition device (16).

8. The system according to claim 7, wherein, The light source ( They are equidistant from each other in terms of angle.

9. The system according to any one of the preceding claims, wherein, The image acquisition device (16) includes an optical sensor configured to capture the image of the object (A) under each illumination condition. Each part (A) irradiated by the irradiation device (12) below j The optical image is converted into the corresponding monochrome digital image. ).

10. The system according to claim 9, wherein, The image acquisition device (16) is a camera or video camera.

11. The system according to claim 9 or 10, wherein, The image acquisition device (16) has an optical axis (Y), which indicates the distance between each part (A) of the object (A) when it is illuminated by the irradiated device (12). j The reflected light beam will enter the focal plane of the optical sensor substantially perpendicularly.

12. The system according to any one of claims 9 to 11, wherein, Each monochrome digital image ( () is a bitmap image.

13. The system according to any one of the preceding claims further includes a support structure (18) that supports the irradiation device (12) and the image acquisition device (16).

14. The system according to claim 13, wherein, The support structure (18) includes a bracket (20) configured to support the image acquisition device (16).

15. The system according to claim 14, wherein, The support structure (18) includes a frame (22) which is connected to the support body (20) and supports the irradiation device (12) on its surface facing the object (A).

16. The system according to claim 15, wherein, The frame (22) has a ring shape or a circular shape.

17. The system according to any one of the preceding claims, wherein, The control unit (28) is configured to sequentially subject the irradiation device (12) to each irradiation condition. ).

18. The system according to any one of the preceding claims, wherein, The control unit (28) is configured to respond whenever the irradiation device (12) presents a corresponding irradiation condition. ) and irradiate the corresponding part (A) of the object (A). j When the image acquisition device (16) is commanded to acquire each monochrome digital image, the image acquisition device (16) is then commanded to acquire each monochrome digital image. ).

19. The system according to any one of the preceding claims further includes a motor configured to move the irradiation device (12) and the image acquisition device (16) integrally in the lateral direction (W) under the guidance of the guide structure (104).

20. The system according to claim 19, wherein, The irradiation device (12) and the image acquisition device (16) can be moved to multiple predetermined positions. ), where, at each predetermined location ( The image acquisition device (16) faces the corresponding part (A) of the object (A). j ).

21. A method for inspecting multiple parts (A1, …, A2) of an object (A). j , …, A m Methods for determining color uniformity; among which, The method includes the following steps: S1) Irradiate at least one corresponding portion (A) of the object (A). j ); S2) Acquire the corresponding part (A) representing the object (A). j The corresponding monochrome digital image () ); The method is characterized in that, in step S1, the corresponding part (A) of the object (A) j ) is selectively irradiated with a corresponding wavelength (λ) i Illuminated by a beam of light; In step S2, the corresponding monochrome digital image ( ) indicates that under the corresponding irradiation conditions ( The corresponding part (A) of the object (A) when irradiated under ) j );and The method further includes the following steps: S3) for multiple predetermined irradiation conditions ( ) and each part (A) that needs to be compared for the chromaticity uniformity of the object (A). j Repeat steps S1 and S2, wherein, under each irradiation condition ( Under these conditions, the light beam utilizes multiple predetermined illumination wavelengths that are different from each other. The corresponding irradiation wavelength (λ) selected in ) i Irradiate at least a corresponding portion (A) of the object (A). j ); S4) for each monochrome digital image ( ), calculate the corresponding luminous intensity value ( The corresponding luminous intensity value represents the luminous intensity value under the corresponding irradiation conditions ( The corresponding part (A) of the object (A) below j The intensity of reflected light; S5) For the portion (A1, …, A) including the object (A). j , …, A m The first part (A) h ) and different from the first part (A) h Part Two (A) k Each combination of ) According to the luminous intensity value ( A mathematical model (M) of at least a part of a function of ), calculating the representation of the first part (A) h ) and the second part (A) k The corresponding chromaticity contrast value of chromaticity uniformity between ) );as well as S6) Based on the chromaticity contrast value ( The output represents the portion (A1, …, A1) of the object (A). j , …,A m The uniformity data (D) of chromaticity uniformity.

22. The method according to claim 22, wherein, In step S3, each luminous intensity value ( ) is calculated as a corresponding monochrome digital image ( A linear function of each associated value in a monochrome pixel.

23. The method according to claim 21 or 22, wherein, In step S5, according to the mathematical model (M), each chromaticity contrast value ( Based on multiple luminous intensity differences ( ) to determine, where each difference in luminous intensity ( ) is for the corresponding irradiation conditions ( ) Calculated between the following two: - The first part (A) h ) luminous intensity value ( )and - Part Two (A) k ) luminous intensity value ( ).

24. The method according to claim 23, wherein, In step S6, each chromaticity contrast value ( ) is compared with a predetermined threshold (S).

25. The method according to claim 24, wherein, In step S6, for the combination ( At least one of the following, when the corresponding chromaticity contrast value ( When the uniformity data (D) is higher than the predetermined threshold (S), the uniformity data (D) indicates that the object (A) is non-compliant (KO).

26. The method according to claim 24 or 25, wherein, In step S6, for all combinations ( ), when each chromaticity contrast value ( When all values ​​are less than or equal to the predetermined threshold (S), the uniformity data (D) indicates that the object (A) is qualified (OK).

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