Method for quantifying an impression of volume given by a head of hair

Abstract

Method for quantifying an impression of volume given by a head of hair (4), comprising the steps consisting in: a) acquiring a front image and / or a side image of the head of hair of a person (1) to be evaluated, b) segmenting the head of hair in each image, c) defining, within the segmented head of hair in the front image, at least one region of interest comprising hair roots (7) and / or at least one region of interest comprising hair lengths (8); and / or defining, within the segmented head of hair in the side image, a region of interest comprising a mass of hair (6), d) delivering a value of at least one characteristic parameter, extracted from one of the regions of interest or corresponding to the sum of the intermediate parameters extracted from several regions of interest, the characteristic parameter being associated with a visual estimate v of the volume given by the head of hair in the regions of interest.

Description

[0001] Description

[0002] Title: Method for quantifying an impression of volume given by a head of hair

[0003] Technical field

[0004] The present invention relates to methods for quantifying an impression of volume given by a head of hair of a person and / or highlighting the effects of at least one cosmetic treatment and / or stimulus on this impression of volume.

[0005] Prior art

[0006] The perception of the volume of a head of hair which a person possesses, which may also be designated as the “impression of volume” given by said head of hair, is a notion which is difficult to characterize objectively. The impression of volume depends on several criteria concerning various zones of the head of hair, which are sometimes assessed differently by observers.

[0007] The current image processing methods known from the prior art make it possible to approximate the exact volume, in the mathematical sense of the term, of hair which an individual possesses but this exact volume cannot be confused with the impression of volume.

[0008] Numerous cosmetic treatments seek to increase or to decrease the impression of volume given by a head of hair, but their effects are difficult to demonstrate in the absence of an objective measure of the impression of volume.

[0009] There thus exists a need for methods which make it possible to objectively quantify an impression of volume given by a head of hair of an individual and to highlight the effects of at least one stimulus and / or cosmetic treatment on this impression of volume.

[0010] Summary of the invention

[0011] The invention aims to meet this need and its subject is thus, according to one of its aspects, a method for quantifying an impression of volume given by a head of hair, comprising the steps consisting in: a) acquiring, notably using a digital acquisition device such as a camera, a front image and / or a side image and / or a back image of the head of hair of a person to be evaluated, b) segmenting, during image processing carried out on a computer or other computing means, the head of hair in each image, c) defining, notably automatically by means of image processing:

[0012] - within the segmented head of hair in the front image, at least one region of interest comprising hair roots and / or at least one region of interest comprising hair lengths;

[0013] - and / or, within the segmented head of hair in the side image, a region of interest comprising a mass of hair;

[0014] - and / or, within the segmented head of hair in the back image, at least one region of interest comprising a portion of the head of hair, d) delivering, notably automatically, a value of at least one characteristic parameter, extracted from one of the regions of interest or corresponding to the optionally weighted sum or average of intermediate parameters which are extracted from several regions of interest, the characteristic parameter being associated with a visual estimate of the volume given by the head of hair in the one or more regions of interest.

[0015] The quantification method according to the invention makes it possible to objectively characterize the impression of volume given by the head of hair by means of at least one parameter. This parameter is labelled “characteristic” because of its association with a visual estimate of the volume.

[0016] The method may, in one embodiment, deliver a value of a single characteristic parameter. As a variant, it may deliver a value of several characteristic parameters.

[0017] By using a front and / or side and / or back image and optionally several regions of interest, the quantification method takes into account the multiplicity of the criteria making it possible to assess the volume of a head of hair.

[0018] The computer or other computer means is, for example, a personal computer, a smartphone, a server or a specialized circuit, and may comprise a graphics card.

[0019] The above value may be delivered by being displayed on a screen and / or be printed and / or sent in the form of a message to a remote terminal.

[0020] Image

[0021] The method may comprise a step a0) preceding step a) consisting in placing the person in front of a uniform background, which is preferably grey in colour, and / or draping their chest with a piece of uniform fabric, which is preferably grey in colour, so as to let their hair fall on the piece of fabric. This step makes it possible to make it easier to segment the head of hair in the images.

[0022] The lighting conditions and / or the acquisition parameters are preferably predefined in order to correspond to a standard image acquisition protocol. This makes it easier to compare the values of a characteristic parameter which are obtained for various heads of hair.

[0023] The front image may be acquired after having styled the head of hair so that the emergence of the hair at the top of the forehead is visible and so that the hair, when its length permits it, is brought to the front of the chest of the person.

[0024] The side image may be acquired after having brought the whole of the head of hair of the person to the rear of their chest.

[0025] The back image may be acquired after having brought the whole of the head of hair of the person to the rear of their chest.

[0026] The hair of the person may be arranged so as to cover their ears. This arrangement of the hair over the ears contributes to avoiding biasing the volume of the head of hair. Arranging the head of hair behind the ears does indeed tend to flatten it artificially.

[0027] These positionings of the head of hair of the person contribute, furthermore, to standardizing the image acquisition protocol.

[0028] Segmentation is a classic task in the field of image processing.

[0029] The head of hair may be segmented by algorithms inspired by conventional image processing methods and / or by algorithms based on artificial intelligence.

[0030] Regions of interest

[0031] What is meant by “region of interest” is a portion or subportion of the segmented head of hair in an image. In certain embodiments, the region of interest may encompass the whole of the segmented head of hair in an image.

[0032] At least one of the regions of interest may be delimited by at least one anatomical landmark of the person, notably an anatomical landmark of the face of the person.

[0033] What is meant by “delimited by at least one anatomical landmark” is that a region of interest may be delimited by at least one horizontal line and / or at least one vertical line the position of which is fixed by an anatomical point of the person, such as their eyes, their nose, their mouth, their ears or their shoulders among others, this list not being limiting.

[0034] “Region of interest comprising hair roots” designates a region of interest encompassing a portion of the head of the person so as to comprise at least a portion of the roots of the hair of the person.

[0035] At least one, and preferably each, region of interest comprising hair roots may encompass the whole of the segmented head of hair extending between a substantially vertical line passing through the middle of the face of the person and a horizontal line passing through an outer comer of an eye of the person.

[0036] Preferably, two regions of interest comprising hair roots are defined on either side of the face of the person in the front image.

[0037] “Region of interest comprising lengths of the hair” designates a region encompassing a portion of the head of hair not touching the skull of the person and potentially going up to the tips of the hair.

[0038] At least one, and preferably each, region of interest comprising hair lengths may encompass the whole of the segmented head of hair extending from a horizontal line passing through an outer comer of an eye of the person up to the hair tips.

[0039] Preferably, two regions of interest comprising lengths of the hair are defined on either side of the face of the person in the front image.

[0040] In one embodiment, two regions of interest comprising roots of the hair and two regions of interest comprising lengths of the hair are defined on either side of the face of the person in the front image so that each region of interest comprising roots of the hair is bordered at one end by a region of interest comprising roots of the hair and at another end by a region of interest comprising lengths of the hair.

[0041] “Region of interest comprising a mass of hair” designates a defined region in the side image encompassing at least the free portion of the hair detached from the skull of the person.

[0042] Preferably, the region of interest comprising a mass of hair encompasses the whole of the segmented head of hair in the side image.

[0043] “Region of interest comprising a portion of the head of hair” designates a defined region in the back image encompassing a portion of the segmented head of hair in this image. At least one, and preferably each, region of interest comprising a portion of the head of hair may encompass the whole of the segmented head of hair extending on one side of a substantially vertical line passing through the middle of the face.

[0044] Preferably, two regions of interest comprising a portion of the head of hair are defined on either side of the substantially vertical line passing through the middle of the face.

[0045] The regions of interest may be defined automatically by implementing algorithms inspired by conventional image processing methods and / or by algorithms based on artificial intelligence, preferably relying on neural networks, in particular on convolutional neural networks (CNNs).

[0046] The automatically defined regions of interest may be specified manually. As a variant, the regions of interest may be defined completely manually.

[0047] Visual estimate

[0048] What is meant by “visual estimate” is that at least one observer, and better still a panel of observers, has given their perception of the volume of the head of hair of the person. The visual estimate may be modelled by an ordinal categorical variable. This variable may have, for example, five levels going from a very weak impression of volume to a strong impression of volume.

[0049] The visual estimate may be performed in each region of interest.

[0050] When the chosen characteristic parameter corresponds to the sum of intermediate parameters extracted from several regions of interest, the visual estimate may be performed globally on the regions of interest concerned.

[0051] The visual estimate may be done by direct notation, by means of an atlas, which may have, for example, five levels, or by indirect notation such as pairwise comparisons.

[0052] The atlas may be specific to the region of interest concerned.

[0053] The visual estimate may be performed by at least one observer other than the person whose head of hair is being evaluated. As a variant, the visual estimate may be performed by the person whose head of hair is being evaluated. In another embodiment, the visual estimate may correspond to the majority vote of several observers (i.e. the most given score is retained), or to the average of their votes.

[0054] Parameters The expression parameter “extracted” from a region of interest is characteristic of the field of image processing. A parameter extracted from a region of interest is a parameter defined within the region of interest. It may be, for example, a distance between two precise points in the region of interest, but also a measure such as height, width, area or perimeter, calculated within the region of interest; this list is not limiting.

[0055] Certain parameters, such as the width of the head of hair at the shoulders, for example, may be defined only on long heads of hair. The length of the head of hair may therefore restrict the number of parameters which may be defined within a region of interest.

[0056] What is meant by a characteristic parameter “associated with a visual estimate” is that a mathematical relationship exists between the characteristic parameter and the visual estimate.

[0057] The association between characteristic parameters and the visual estimate may depend on the length of the head of hair. Certain parameters may be associated with the visual estimate on a short head of hair and not have the same association on a medium or long head of hair.

[0058] The characteristic parameter may predict the visual estimate of the volume given by the head of hair in the one or more regions of interest.

[0059] The characteristic parameter may be correlated with the visual estimate with a correlation coefficient which is at least greater than 0.45, better still greater than 0.5, better still greater than 0.6, even better still greater than 0.7, even better still greater than 0.8, even better still greater than 0.9.

[0060] The correlation coefficient may be calculated by means of the Spearman method. As a variant, the correlation coefficient may be calculated by means of another method, for example by means of the Pearson method.

[0061] In one embodiment where at least one characteristic parameter is extracted from a region of interest comprising hair roots, the characteristic parameter may be chosen from among an area E, E.1 of the region of interest and a maximum root detachment height L4, L4.1.

[0062] “Maximum root detachment height” designates a parameter L4, L4.1 consisting of the height between the highest point on a vertical axis Z of the region of interest comprising roots and a horizontal line extending from the highest point of the face of the person. In one embodiment where two regions of interest comprising hair roots are defined on either side of the face of the person, at least one characteristic parameter may correspond to the optionally weighted sum or average of two identical intermediate parameters which are each extracted from one of the two regions, the intermediate parameter being chosen, for example, from among an area E, E.1 of the region of interest and a root detachment height L4, L4.1.

[0063] In one embodiment where at least one characteristic parameter is extracted from a region of interest comprising hair lengths, the characteristic parameter may be chosen from among an area C, C.1 of the region of interest comprising hair lengths, a width of the head of hair at the chin e3, e3.1 and a width of the head of hair at the mouth e2, e2.1.

[0064] The “width of the head of hair at the chin” corresponds to the length, measured in the region of interest comprising hair lengths, of a horizontal line extending from the lowest point on a vertical axis Z of the chin of the person.

[0065] The “width of the head of hair at the mouth” corresponds to the length, measured in the region of interest comprising hair lengths, of a horizontal line extending from the comer of the lips of the person.

[0066] In one embodiment where two regions of interest comprising hair lengths are defined on either side of the face of the person, at least one characteristic parameter may correspond to the optionally weighted sum or average of two identical intermediate parameters which are each extracted from one of the two regions, the intermediate parameter being chosen, for example, from among an area C, C.l of the region of interest comprising hair lengths, a width of the head of hair at the chin e3, e3.1 and a width of the head of hair at the mouth e2, e2.1.

[0067] In one embodiment where at least one characteristic parameter is extracted from a region of interest comprising a mass of hair, the characteristic parameter may be chosen from among an area Ai of the region of interest comprising a mass of hair, a restricted area A2of the mass of hair and a width of the head of hair d2 at the opening of the auditory canal.

[0068] In one embodiment where at least one characteristic parameter is extracted from a region of interest comprising a portion of the head of hair, the characteristic parameter may be chosen from among: an area A, A.1 of the region of interest, a maximum length L, L.1 of the head of hair in the region of interest or a width of the head of hair d, d.1 in various positionings. Stimulus and treatment

[0069] The stimulus according to the invention may be chosen from among a chemical stimulus, a thermal stimulus, a mechanical stimulus or an electromagnetic stimulus, notably a light or microwave stimulus or a combination thereof.

[0070] The treatment is non-therapeutic. The treatment is a cosmetic treatment, notably via the application of a cosmetic product promoting the regrowth or the beautification of the head of hair, notably the thickening of the hair.

[0071] What is meant by “cosmetic product” is a product as defined in Directive 93 / 35ZEEC of 14 June 1993, modifying Directive 76 / 768 / EEC.

[0072] The cosmetic product may be selected from among rinsed and unrinsed products, styling products and hair lotions, shampoos, conditioners, lacquers, hair loss products, foams, sprays or oils, among others, this list not being limiting.

[0073] The cosmetic treatment may comprise mechanical shaping, notably by means of styling tools and / or devices associated or not associated with products, for example a hairdryer, hair straighteners or a styling brush, this list not being limiting.

[0074] What is meant by “reference stimulus and / or treatment” is a stimulus and / or a treatment the effects of which on an impression of volume given by a head of hair, for example an effect leading to a greater impression of volume, are known from the prior art and / or from prior experiments.

[0075] Methods for evaluating the effect of a stimulus and / or of a treatment

[0076] Another subject of the invention, according to another one of its aspects, is a method for evaluating the effect of a stimulus and / or of a treatment on an impression of volume given by a head of hair, comprising the steps consisting in: a) quantifying the impression of volume given by the head of hair by means of the quantification method as defined above, b) repeating step a) on the head of hair after exposure to the action of the stimulus and / or of the treatment, c) comparing the values of the characteristic parameters delivered in the two steps and generating at least one item of information relating to the action of the stimulus and / or of the treatment on the impression of volume.

[0077] In a variant of the method for evaluating the effect of a stimulus and / or of a treatment described above, step c) may be replaced with step c’), consisting in delivering, notably automatically, a value of at least one characteristic parameter, extracted from one of the regions of interest or corresponding to the optionally weighted sum or average of intermediate parameters extracted from several regions of interest, the characteristic parameter exhibiting variation before and after exposure to said stimulus and / or treatment associated with the variation in the visual estimate of the volume given by the head of hair before and after exposure, notably correlated with a correlation coefficient, preferably calculated according to the Spearman method, which is at least greater than 0.7, better still greater than 0.8, even better still greater than 0.9.

[0078] Another subject of the invention, according to another one of its aspects, is a method for evaluating the effect of a stimulus and / or of a treatment on an impression of volume given by a head of hair, wherein at least two heads of hair are exposed differently to the stimulus and / or to the treatment, and wherein the value of at least one characteristic parameter delivered by means of the quantification method as defined above is compared, for the various heads of hair.

[0079] The exposure to the stimulus may be different over time between the heads of hair. The treatment may be applied at different doses between the heads of hair.

[0080] One of the heads of hair may not be exposed to the stimulus and / or treatment, unlike the one or more other heads of hair.

[0081] Treatment method

[0082] Another subject of the invention is a method for cosmetically treating the head of hair of a person, comprising the steps consisting in: a) quantifying the impression of volume given by the head of hair by means of the quantification method as defined above, b) selecting a treatment of the head of hair, notably a treatment comprising applying a cosmetic product and / or mechanical shaping by means of styling tools, depending on the result of the quantification in a) and an objective of the impression of volume to be reached, c) performing said treatment.

[0083] Preferably, in the case where the treatment comprises applying a cosmetic product, the cosmetic product is selected on the basis of a database which lists, for each of the products, the effect of the product on the impression of volume.

[0084] Preferably, the cosmetic product is also selected on the basis of the entry of a choice, by the person, of the desired objective of the impression of volume.

[0085] The selection may comprise the steps consisting in determining which product best makes it possible to reach the objective of the impression of volume desired by the person knowing the initial impression of volume given by their hair. Thus, for example, if the person desires to have hair giving the impression of a high volume, and has hair giving a very low impression of volume, a product having a strong volumizing effect may be selected; by contrast, if the person desires to keep the current impression of volume and has hair already giving a strong impression of volume, a product having a neutral effect on the impression of volume may be selected. Similarly, for a person desiring to reduce their impression of volume, an appropriate product or shaping may be selected.

[0086] Finally, for a person desiring an average impression of volume, products with a weak volumizing effect or, by contrast, which reduce the volume somewhat may be chosen according to the initial impression of volume.

[0087] System

[0088] Another subject of the invention, according to another one of its aspects, is a system for implementing a method according to the invention, comprising: an image acquisition unit, for example a camera, a computing means, notably a unit which is capable of storing the images and / or of sending them to an integrated computer or to a remote computing server by means of a wired or wireless connection, this computing means being configured to segment the head of hair in the one or more images, define at least one region of interest and deliver a value of at least one characteristic parameter extracted from one of the regions of interest or corresponding to the optionally weighted sum or average of intermediate parameters which are extracted from several regions of interest.

[0089] The unit for acquiring the images may be separated from the rest of the system and connected by a wired or wireless connection.

[0090] The computing means may comprise a computer integrated into the system, as mentioned above, such as a microcomputer, or be remote such as a computing server connected to the system by a wired or wireless connection.

[0091] The computing means may be a computer, a smart object, for example a smart mirror, a smartphone,

[0092] The computing means may be integrated into any image capturing device in order to carry out automatic measurement of volume of the head of hair, for example into the following existing devices: “Canfield scientific Vectra”, “Cosderma photographic bench”, “Headscan and I-robot from Orion Technolab”.

[0093] The user interface may be included in the system or separate, such as a display screen.

[0094] The system may be miniaturized in order to be used at an advice or sales point, in a styling salon or at the home of a user.

[0095] The system may be used to recommend products, devices and / or services or intended for diagnosing the volume of the head of hair. It may also make it possible to monitor the volume of the head of hair, notably depending on treatments and / or stimuli applied to the head of hair and on the impact of the exposome on the head of hair.

[0096] Such monitoring may serve to measure the progress in the mastering of treatment, for example styling or shaping, techniques by professionals or users.

[0097] Brief description of the drawings

[0098] The invention may be better understood upon reading the following description, of nonlimiting examples of implementations thereof, and upon examining the appended drawing, in which: [Fig 1] depicts, in a schematic view, various steps of one example of a quantification method in accordance with the invention,

[0099] [Fig 2] depicts a side view of the head of hair of a user and a system which makes it possible to acquire and process the side view,

[0100] [Fig 3] is a front image of the head of hair of the person of Figure 2,

[0101] [Fig 4] is the same front image as Figure 3, in which various parameters are depicted,

[0102] [Fig 5] is a correlation matrix of parameters relating to the regions comprising hair roots defined in Figures 3 and 4, and a visual estimate of the impression of volume,

[0103] [Fig 6] is a set of three correlation matrices of parameters relating to the regions comprising hair lengths defined in Figures 3 and 4 and a visual estimate of the impression of volume, each matrix depicting a situation where the head of hair of the person is of a different length,

[0104] [Fig 7] is the same side image as Figure 2, in which various parameters are depicted,

[0105] [Fig 8] is a set of three correlation matrices of parameters relating to a region comprising a mass of hair defined in Figures 2 and 7 and a visual estimate of the impression of volume, each matrix depicting a situation where the head of hair of the person is of different length,

[0106] [Fig 9] is a back image of the head of hair of the person of Figure 2,

[0107] [Fig 10] is a correlation matrix of variations, before and after exposure to a stimulus and / or treatment, in parameters relating to the regions comprising hair roots defined in Figures 3 and 4, and a variation, before and after exposure, in a visual estimate of the impression of volume,

[0108] [Fig 11] is a correlation matrix of variations, before and after exposure to a stimulus and / or treatment, in parameters relating to the regions comprising hair lengths defined in Figures 3 and 4, and a variation, before and after exposure, in a visual estimate of the impression of volume,

[0109] [Fig 12] is a correlation matrix of variations, before and after exposure to a stimulus and / or treatment, in parameters relating to a region comprising a mass of hair defined in Figures 2 and 7, and a variation, before and after exposure, in a visual estimate of the impression of volume. Detailed description

[0110] Various steps of a method for quantifying an impression of volume given by a head of hair according to the invention will be described with reference to Figures 1 to 11.

[0111] Step a0of Figure 1 aims to create standard acquisition conditions and may consist in placing, as illustrated in Figure 2, a person 1 in front of a uniform background 2 and in draping their chest with a piece of uniform fabric 3 so as to let their head of hair 4 fall on the piece of fabric.

[0112] During step a), the whole of the head of hair 4 of the person is brought to the rear of their chest, the hair arranged so as to cover the ears at least in part, as may be seen in Figure 2 a). A side image is acquired, using any digital image acquisition device 9, for example a colour camera with a CMOS sensor. A back image, as may be seen in Figure 9, is then acquired.

[0113] The head of hair 4 of the person 1 is then styled so that the emergence of the hair at the top of the forehead is visible and so that the hair is brought to the front of the chest of the person as illustrated in Figure 3. A front image of the head of hair 4 is acquired by virtue of the digital image acquisition device 9.

[0114] During step b), the previously acquired images are processed by a computer 10 of PC type, for example; or any other suitable computing means, as depicted in Figure 2 b), and the head of hair 4 is segmented by means of a segmentation algorithm, for example an algorithm making use of convolutional neural networks (CNNs).

[0115] In step c), a region of interest comprising a mass of hair 6 is defined in the side image, for example automatically by means of image processing, or as a variant defined by an operator using a tool which makes it possible to draw an outline on the image. This region encompasses the whole of the segmented head of hair in the side image, as Figure 2 shows. In the back image, as may be seen in Figure 9, two regions of interest 11 and 12 comprising a portion of the head of hair are defined on either side of the substantially vertical line passing through the middle of the face 5.

[0116] During step c), two regions of interest comprising hair roots 7 are defined in the front image, depicted in Figure 3, on either side of the face of the person. These two regions 7 encompass the whole of the segmented head of hair extending between a substantially vertical line 5 passing through the middle of the face and a horizontal line passing through an outer corner of an eye of the person.

[0117] Two regions of interest comprising hair lengths 8 are also defined in the front image on either side of the face of the person. These two regions 8 encompass the whole of the segmented head of hair extending from a horizontal line passing through an outer comer of an eye of the person 1 up to the tips of the hair.

[0118] A set of parameters may be extracted by calculation using a computer 10 or any other suitable computing means, from the regions 7 and 8 as depicted in Figure 4, the below list not being exhaustive, the extraction bearing on all or some of the parameters listed:

[0119] A: the area of the top-right portion of the head of hair 4 beginning at the outer comer of the eye and stopping at the centre parting 5,

[0120] A.1 : the area of the top-left portion of the head of hair beginning at the outer comer of the eye and stopping at the centre parting 5,

[0121] At: the sum of A and A.1,

[0122] E: the area of the region of interest comprising hair roots 7 which is located to the right of the face of the person,

[0123] E.1 : the area of the region of interest comprising hair roots 7 which is located to the left of the face of the person,

[0124] Et: the sum of E and E.1,

[0125] C: the area of the region of interest comprising hair lengths 8 which is located to the right of the face of the person,

[0126] C.1 : the area of the region of interest comprising hair lengths 8 which is located to the left of the face of the person,

[0127] Ct: the sum of C and C.l,

[0128] L5 : positioned half-way between the outer corner of the eye and the centre parting, L5 illustrates the length between the base of the head of hair and the top of the head of hair in the top-right of the forehead,

[0129] L5.1 : positioned half-way between the outer corner of the eye and the centre parting, L5.1 illustrates the length between the base of the head of hair and the top of the head of hair in the top-left of the forehead,

[0130] L5m: the average between L5 and L5.1,

[0131] L4 : the maximum rightward root detachment height, L4.1 : the maximum leftward root detachment height,

[0132] L4m: the average between L4 and L4.1, el : the rightward width of the head of hair at the eyes, el .1 : the leftward width of the head of hair at the eyes, elt: the sum of el and el. l, e2: the rightward width of the head of hair at the mouth, e2.1 : the leftward width of the head of hair at the mouth, e2t: the sum of e2 and e2.1, e3: the rightward width of the head of hair at the chin, e3.1 : the leftward width of the head of hair at the chin, e3t: the sum of e3 and e3.1, e4: the rightward width of the head of hair at the shoulders, e4.1 : the leftward width of the head of hair at the shoulders, e4t: the sum of e4 and e4.1, e5: the rightward width of the head of hair at the chest, e5.1 : the leftward width of the head of hair at the chest, e5t: the sum of e5 and e5.1, e6: the rightward width of the head of hair immediately above the tips of the hair, e6.1 : the leftward width of the head of hair immediately above the tips of the hair, e6t: the sum of e6 and e6.1.

[0133] Standard parameters such as parameters of the face, notably relating to its shape, are also annotated in the front image in order to serve as elements of comparison in the correlation matrices:

[0134] L2: the length of the head of hair between a horizontal line passing through an outer comer of the eye of the person and the tips of the hair,

[0135] LI : the total length of the head of hair from the top of the head to the tips, b: the half-length of the face or major radius of the ellipse of the face, a: the half-width of the face or the minor radius of the ellipse of the face, B: the area of the face. In the correlation matrices of Figures 5, 6 and 8, v is the visual estimate of the volume given by the head of hair in the one or more regions of interest concerned, v may be modelled by an ordinal categorical variable with several levels, for example with 5 levels, going from a very weak impression of volume to a strong impression of volume. The visual estimate may notably have been performed by a panel of observers, for example naive observers, consumers or experts in the field, by comparing batches of images by pairwise comparison, or using several atlases, for example three in number, in image self-evaluation or evaluation, each specific to one of the regions comprising hair roots, hair lengths or a mass of hair. The correlation coefficients of all of the matrices were calculated by the Spearman method.

[0136] The correlation matrix of Figure 5 is concerned with the parameters extracted from the regions of interest 7 comprising hair roots or with the sum or the average of these parameters, then acting as intermediate parameters. The parameters having a coefficient which is greater than 0.45 of correlation with the visual estimate are the areas E, E.l of the regions of interest and the maximum root detachment heights L4, L4.1 as well as the respective sum of these parameters Et and L4t.

[0137] The correlation matrices of Figure 6 are concerned with the parameters extracted from the regions of interest 8 comprising hair lengths or with the sum of these parameters, then acting as intermediate parameters.

[0138] The matrix of Figure 6 a) relates to a short head of hair; thus, not all the parameters are defined. The matrix of Figure 6 b) relates to a medium head of hair, comprising more parameters than the matrix of Figure 6 a). The matrix of Figure 6 c) relates to a long head of hair; an even larger number of parameters is then defined.

[0139] According to the length of the head of hair of the person, the magnitude of the correlation between similarly defined parameters and the visual estimate varies. The parameters having the highest correlation coefficients are the areas C, C. l of the regions of interest comprising hair lengths, the widths of the head of hair at the chin e3, e3.1 and the widths of the head of hair at the mouth e2, e2.1, as well as the respective sums of these parameters: Ct, e3t and e2t.

[0140] In the side image, another set of parameters is extracted from the region of interest comprising a mass of hair 6, as depicted in Figure 7, the below list not being exhaustive, the extraction bearing on all or some of the parameters listed: Al : the area of the region of interest comprising a mass of hair,

[0141] A2: the restricted area of the mass of hair, dl : the width of the head of hair at the middle of the forehead, d2: the width of the head of hair at the opening of the auditory canal, d3: the width of the head of hair at the bottom of the mouth, d4: the width of the head of hair at the shoulders, d5: the width of the head of hair at the chest, d6: the width of the head of hair immediately before the tips of the hair.

[0142] Similarly to Figure 6, the matrices of Figure 8 relate to different lengths of the head of hair. The parameters having the highest coefficients of correlation with the visual estimate are the area Ai of the region of interest comprising a mass of hair, the restricted area A2of the mass of hair and the width of the head of hair d2 at the opening of the auditory canal.

[0143] In the back image, another set of parameters is extracted from each of the two regions of interest 11 and 12 comprising a portion of the head of hair, as depicted in Figure 9, the below list not being exhaustive, the extraction bearing on all or some of the parameters listed:

[0144] A, Al : the area of the region of interest,

[0145] L, LI : the length of the region of interest, dl, dl.l to d6, d6.1 : the width of the head of hair in each region of interest in different positionings.

[0146] The correlation matrices of Figures 10 to 12 illustrate another aspect of the invention, the method making it possible to evaluate the effect of a stimulus and / or a treatment on an impression of volume given by the head of hair.

[0147] The correlation matrices of Figures 10 to 12 relate to the regions comprising hair roots 7, the regions of interest comprising hair lengths 8 and the region of interest comprising a mass of hair 6, respectively.

[0148] During the evaluation method, the impression of volume given by the head of hair of a person is quantified by virtue of the previously described method before and after exposure to a stimulus and / or a treatment. The association between the variations, before and after exposure, in the values of the parameters delivered by the quantification method and the variations in the visual estimate before and after exposure is examined.

[0149] For reasons of simplicity, the variations in a parameter are designated by the name of the parameter in the legends of these matrices.

[0150] The invention is not limited to the examples described above.

[0151] Other delimitations of regions may be established.

[0152] Other parameters or optionally weighted sums of parameters may be defined.

[0153] The selection thresholds of the characteristic parameters may vary.

Claims

Claims1. Method for quantifying an impression of volume given by a head of hair (4), comprising the steps consisting in: a) acquiring, notably using a digital acquisition device (9) such as a camera, a front image and / or a side image and / or a back image of the head of hair of a person (1) to be evaluated, b) segmenting, during image processing carried out on a computer or other computing means (10), the head of hair in each image, c) defining, notably automatically by means of image processing:- within the segmented head of hair in the front image, at least one region of interest comprising hair roots and / or at least one region of interest comprising hair lengths;- and / or, within the segmented head of hair in the side image, a region of interest comprising a mass of hair;- and / or, within the segmented head of hair in the back image, at least one region of interest comprising a portion of the head of hair, d) delivering, notably automatically, a value of at least one characteristic parameter, extracted from one of the regions of interest or corresponding to the, optionally weighted, sum or average of intermediate parameters which are extracted from several regions of interest, the characteristic parameter being associated with a visual estimate v of the volume given by the head of hair in the one or more regions of interest, at least one of the regions of interest being delimited by at least one anatomical landmark of the person, notably an anatomical landmark of the face of the person, each region of interest comprising hair roots (7) encompassing the whole of the segmented head of hair extending between a substantially vertical line passing through the middle of the face of the person (1) and a horizontal line passing through an outer corner of an eye of the person, at least one characteristic parameter being extracted from a region of interest comprising hair roots (7), the characteristic parameter being chosen from among an area E, area of the region of interest comprising hair roots (7) which is located to theright of the face of the person, E.1, area of the region of interest comprising hair roots (7) which is located to the left of the face of the person and a maximum root detachment height L4, L4.1.

2. Method for quantifying an impression of volume given by a head of hair (4) according to the preceding claim, two regions of interest comprising hair roots (7) being defined on either side of the face of the person, at least one characteristic parameter corresponding to the sum or to the average of two identical intermediate parameters each extracted from one of the two regions, the intermediate parameter being chosen, for example, from among the areas E, E.1 of the region of interest and a root detachment height L4, L4.1.

3. Method for quantifying an impression of volume given by a head of hair (4), comprising the steps consisting in: a) acquiring, notably using a digital acquisition device (9) such as a camera, a front image and / or a side image and / or a back image of the head of hair of a person (1) to be evaluated, b) segmenting, during image processing carried out on a computer or other computing means (10), the head of hair in each image, c) defining, notably automatically by means of image processing:- within the segmented head of hair in the front image, at least one region of interest comprising hair roots and / or at least one region of interest comprising hair lengths;- and / or, within the segmented head of hair in the side image, a region of interest comprising a mass of hair;- and / or, within the segmented head of hair in the back image, at least one region of interest comprising a portion of the head of hair, d) delivering, notably automatically, a value of at least one characteristic parameter, extracted from one of the regions of interest or corresponding to the, optionally weighted, sum or average of intermediate parameters which are extracted from several regions of interest, the characteristic parameter being associated with a visual estimate v of the volume given by the head of hair in the one or more regions of interest, at least one of the regions of interest being delimited by at least one anatomical landmark of the person, notably an anatomical landmark of the face of the person,each region of interest comprising hair roots (7) encompassing the whole of the segmented head of hair extending between a substantially vertical line passing through the middle of the face of the person (1) and a horizontal line passing through an outer corner of an eye of the person, two regions of interest comprising hair roots (7) being defined on either side of the face of the person, at least one characteristic parameter corresponding to the sum or to the average of two identical intermediate parameters each extracted from one of the two regions, the intermediate parameter being chosen, for example, from among an area E, area of the region of interest comprising hair roots (7) which is located to the right of the face of the person, E.1, area of the region of interest comprising hair roots (7) which is located to the left of the face of the person, and a root detachment height L4, L4.1.

4. Method for quantifying an impression of volume given by a head of hair (4), comprising the steps consisting in: a) acquiring, notably using a digital acquisition device (9) such as a camera, a front image and / or a side image and / or a back image of the head of hair of a person (1) to be evaluated, b) segmenting, during image processing carried out on a computer or other computing means (10), the head of hair in each image, c) defining, notably automatically by means of image processing:- within the segmented head of hair in the front image, at least one region of interest comprising hair roots and / or at least one region of interest comprising hair lengths;- and / or, within the segmented head of hair in the side image, a region of interest comprising a mass of hair;- and / or, within the segmented head of hair in the back image, at least one region of interest comprising a portion of the head of hair, d) delivering, notably automatically, a value of at least one characteristic parameter, extracted from one of the regions of interest or corresponding to the optionally weighted sum or average of intermediate parameters which are extracted from several regions of interest,the characteristic parameter being associated with a visual estimate v of the volume given by the head of hair in the one or more regions of interest, at least one of the regions of interest being delimited by at least one anatomical landmark of the person, notably an anatomical landmark of the face of the person, each region of interest comprising hair lengths (8) encompassing the whole of the segmented head of hair (4) extending from a horizontal line passing through an outer corner of an eye of the person up to the tips of the hair, at least one characteristic parameter being extracted from a region of interest comprising hair lengths (8), the characteristic parameter being chosen from among an area C, area of the region of interest comprising hair lengths (8) which is located to the right of the face of the person, C.1, area of the region of interest comprising hair lengths (8) which is located to the left of the face of the person, a width of the head of hair at the chin e3, e3.1 and a width of the head of hair at the mouth e2, e2.1.

5. Method for quantifying an impression of volume given by a head of hair (4), comprising the steps consisting in: a) acquiring, notably using a digital acquisition device (9) such as a camera, a front image and / or a side image and / or a back image of the head of hair of a person (1) to be evaluated, b) segmenting, during image processing carried out on a computer or other computing means (10), the head of hair in each image, c) defining, notably automatically by means of image processing:- within the segmented head of hair in the front image, at least one region of interest comprising hair roots and / or at least one region of interest of interest comprising hair lengths;- and / or, within the segmented head of hair in the side image, a region of interest comprising a mass of hair;- and / or, within the segmented head of hair in the back image, at least one region of interest comprising a portion of the head of hair, d) delivering, notably automatically, a value of at least one characteristic parameter, extracted from one of the regions of interest or corresponding to the optionally weighted sum or average of intermediate parameters which are extracted from several regions of interest,the characteristic parameter being associated with a visual estimate v of the volume given by the head of hair in the one or more regions of interest, at least one of the regions of interest being delimited by at least one anatomical landmark of the person, notably an anatomical landmark of the face of the person, each region of interest comprising hair lengths (8) encompassing the whole of the segmented head of hair (4) extending from a horizontal line passing through an outer corner of an eye of the person up to the tips of the hair, two regions of interest comprising hair lengths (8) being defined on either side of the face of the person, at least one characteristic parameter corresponding to the sum or to the average of two identical intermediate parameters each extracted from one of the two regions, the intermediate parameter being chosen from among an area C, area of the region of interest comprising hair lengths (8) which is located to the right of the face of the person, C. l, area of the region of interest comprising hair lengths (8) which is located to the left of the face of the person, a width of the head of hair at the chin e3, e3.1 and a width of the head of hair at the mouth e2, e2.1.

6. Method for quantifying an impression of volume given by a head of hair (4), comprising the steps consisting in: a) acquiring, notably using a digital acquisition device (9) such as a camera, a front image and / or a side image and / or a back image of the head of hair of a person (1) to be evaluated, b) segmenting, during image processing carried out on a computer or other computing means (10), the head of hair in each image, c) defining, notably automatically by means of image processing:- within the segmented head of hair in the front image, at least one region of interest comprising hair roots and / or at least one region of interest comprising hair lengths;- and / or, within the segmented head of hair in the side image, a region of interest comprising a mass of hair;- and / or, within the segmented head of hair in the back image, at least one region of interest comprising a portion of the head of hair, d) delivering, notably automatically, a value of at least one characteristic parameter, extracted from one of the regions of interest or corresponding tothe optionally weighted sum or average of intermediate parameters which are extracted from several regions of interest, the characteristic parameter being associated with a visual estimate v of the volume given by the head of hair in the one or more regions of interest, the region of interest comprising a mass of hair (6) encompassing the whole of the segmented head of hair in the side image, at least one characteristic parameter being extracted from a region of interest comprising a mass of hair (6), the characteristic parameter being chosen from among an area Ai of the region of interest comprising a mass of hair, a restricted area A2of the mass of hair and a width of the head of hair d2 at the opening of the auditory canal.

7. Method for quantifying an impression of volume given by a head of hair (4) according to any one of the preceding claims, the characteristic parameter being correlated with the visual estimate v with a correlation coefficient which is at least greater than 0.45, better still greater than 0.5, better still greater than 0.6, even better still greater than 0.7, even better still greater than 0.8, even better still greater than 0.9.

8. Method for quantifying an impression of volume given by a head of hair (4) according to any one of the preceding claims, the correlation coefficient being calculated by means of the Spearman method.

9. Method for quantifying an impression of volume given by a head of hair (4) according to any one of the preceding claims with the exception of any attachment to Claim 4 or 5, each region of interest comprising hair lengths (8) encompassing the whole of the segmented head of hair (4) extending from a horizontal line passing through an outer corner of an eye of the person up to the tips of the hair.

10. Method for quantifying an impression of volume given by a head of hair (4) according to the preceding claim or any attachment to Claim 5, at least one characteristic parameter being extracted from a region of interest comprising hair lengths (8), the characteristic parameter being chosen from among an area C, area of the region of interest comprising hair lengths (8) which is located to the right of the face of the person, C. l, area of the region of interest comprising hair lengths (8) which is located to the left of the face of the person, a width of the head of hair at the chin e3, e3.1 and a width of the head of hair at the mouth e2, e2.1.

11. Method for quantifying an impression of volume given by a head of hair (4) according to Claim 9 or any attachment to Claim 4, two regions of interest comprising hair lengths (8) being defined on either side of the face of the person, at least one characteristic parameter corresponding to the sum or to the average of two identical intermediate parameters each extracted from one of the two regions, the intermediate parameter being chosen, for example, from among an area C, area of the region of interest comprising hair lengths (8) which is located to the right of the face of the person, C. l, area of the region of interest comprising hair lengths (8) which is located to the left of the face of the person, a width of the head of hair at the chin e3, e3.1 and a width of the head of hair at the mouth e2, e2.1.

12. Method for quantifying an impression of volume given by a head of hair (4) according to any one of the preceding claims with the exception of any attachment to Claim 6, the region of interest comprising a mass of hair (6) encompassing the whole of the segmented head of hair in the side image.

13. Method for quantifying an impression of volume given by a head of hair (4) according to the preceding claim, at least one characteristic parameter being extracted from a region of interest comprising a mass of hair (6), the characteristic parameter being chosen from among an area Ai of the region of interest comprising a mass of hair, a restricted area A2of the mass of hair and a width of the head of hair d2 at the opening of the auditory canal.

14. Method for evaluating the effect of a stimulus and / or of a treatment on an impression of volume given by a head of hair (4), comprising the steps consisting in: a) quantifying the impression of volume given by the head of hair by means of the quantification method according to any one of the preceding claims, b) repeating step a) on the head of hair after exposure to the action of the stimulus and / or of the treatment, c) comparing the values of the characteristic parameters delivered in the two steps and generating at least one item of information relating to the action of the stimulus and / or of the treatment on the impression of volume.

15. Method for evaluating the effect of a stimulus and / or of a treatment on an impression of volume given by a head of hair (4), wherein at least two heads of hair are exposed differently to the stimulus and / or to the treatment, and wherein the value of at leastone characteristic parameter delivered by means of the quantification method according to any one of Claims 1 to 13 are compared, for the various heads of hair.

16. Method according to one of the two immediately preceding claims, the treatment being a cosmetic treatment, notably via the application of a product promoting the regrowth or the beautification of the head of hair, notably the thickening of the hair.

17. Method for cosmetically treating the head of hair of a person, comprising the steps consisting in: a) quantifying the impression of volume given by the head of hair by means of the method for quantifying an impression of volume given by a head of hair (4) according to any one of Claims 1 to 13, b) selecting a treatment of the head of hair, notably a treatment comprising applying a cosmetic product and / or mechanical shaping by means of styling tools, depending on the result of the quantification in a) and an objective of the impression of volume to be reached, c) performing said treatment.

18. System for implementing a method according to any one of the preceding claims, comprising: an image acquisition unit, for example a camera, a computing means, notably a unit which is capable of storing the images and / or of sending them to an integrated computer or to a remote computing server by means of a wired or wireless connection, this computing means being configured to segment the head of hair in the one or more images, define at least one region of interest and deliver a value of at least one characteristic parameter extracted from one of the regions of interest or corresponding to the optionally weighted sum or average of intermediate parameters which are extracted from several regions of interest.

Images