Method of creating an image comprising an iris

Abstract

Title: Method for creating an image comprising an iris Method for creating an image comprising an iris, the creation method comprising:- a first step (E1) of acquiring a first digital image (Im1) comprising an iris (Ir1), by means of a photographic apparatus (2), then- a second step (E2) of determining an internal contour (Ci1) and an external contour (Ce1) of the iris of the first image, then- a third step (E3) of creating a second digital image (Im2) comprising an iris (Ir2), the iris of the second image comprising an internal circular contour (Ci2) and an external circular contour (Ce2), the external circular contour being centered on the internal circular contour, each given pixel of the second image between the internal circular contour and the external circular contour being defined by means of a projection of at least one corresponding pixel of the first image. Figure to be published with the abstract: Figure 2

Description

Title of the invention: Method for creating an image comprising an iris Technical field of the invention

[0001] The invention relates to a method for creating an image comprising an iris. The invention also relates to an ornamental object comprising an image obtained by such a method. The invention also relates to a photography installation comprising hardware and software means configured to implement such a method. State of the prior art

[0002] Each person's iris has unique and particularly aesthetic characteristics. To highlight these characteristics, it is known to provide photographic supports comprising an enlarged representation of a person's iris. Such a photographic support makes it possible to observe numerous details of the iris. Such a photographic support thus forms a unique ornamental object, which can, for example, be hung on a wall to decorate a home.

[0003] To produce such photographic media, it is known to take a first close-up digital photograph of the eye using a digital camera. Then, the first photograph is retouched using image processing software. The retouching generally consists of masking the sclera around the iris, or even removing imperfections from the first photograph, for example removing a light reflection appearing on the iris. The image obtained is then printed on a support.

[0004] Retouching photographs requires both the expertise of a photographer accustomed to recognizing defects in digital photographs, and also skills in using image processing software. Thus, the photographic supports known from the state of the art are complicated to manufacture and therefore relatively expensive. In addition, the final result is not always optimal. In particular, it is noted that photographs printed on a support still include defects. The quality of ornamental objects manufactured with the processes known from the state of the art is therefore quite fluctuating and depends heavily on the quality of the processing provided by the photographer to the photograph. Presentation of the invention

[0005] The object of the invention is to provide a method for creating an image comprising an iris as well as an ornamental object comprising such an image remedying the above drawbacks and improving methods and ornamental objects known in the art. prior.

[0006] More specifically, a first object of the invention is an automated method for creating a high-quality image comprising an iris. Summary of the invention

[0007] The invention relates to a method of creating an image comprising an iris, the creation method comprising: - a first stage of acquiring a first digital image comprising an iris, using a camera, then - a second step of determining an internal contour and an external contour of the iris of the first image, then - a third step of creating a second digital image comprising an iris, the iris of the second image comprising an internal circular contour and an external circular contour, the external circular contour being centered on the internal circular contour, each given pixel of the second image between the inner circular contour and the outer circular contour being defined by means of a projection of at least one corresponding pixel of the first image, the at least one corresponding pixel being between the inner contour and the outer contour of the first image.

[0008] The second step may comprise a sub-step of determining an internal ellipse corresponding to the internal contour of the iris of the first image, and / or a sub-step of determining an external ellipse corresponding to the external contour of the iris of the first image.

[0009] The second step may include: - a first sub-step of creating an intermediate image comprising an iris, the intermediate image being obtained by reducing the first image, then - a second sub-step of determining an internal contour and an external contour of the iris of the intermediate image, then - a third sub-step of calculating the internal contour and the external contour of the iris of the first image by enlarging respectively the internal contour of the iris of the intermediate image and the external contour of the iris of the intermediate image.

[0010] Said second sub-step may comprise: - a sub-step of determining an intermediate internal ellipse corresponding to the internal contour of the iris of the intermediate image, then - a sub-step of determining an intermediate external ellipse corresponding to the external contour of the iris of the intermediate image.

[0011] The parameters defining the intermediate inner ellipse and the intermediate outer ellipse can be determined by an iterative non-least squares method. linear.

[0012] The first step may include: - a sub-step of adjusting the camera such that a height of the iris of the first image is at least equal to one half of a height of the first image and / or such that a width of the iris of the first image is at least equal to one third of a width of the first image and / or such that the center of the first image is included within the inner contour of the iris of the first image, and / or - a sub-step of applying mechanical stress to the contour of a person's eye so as to make the entire iris of that eye visible, and / or - a sub-step of a treatment that causes the pupil of a person's eye to constrict.

[0013] A ratio of the diameter of the inner circular contour to the diameter of the outer circular contour may be equal to a predetermined value, for example a value between 0.2 and 0.3.

[0014] The third step may comprise for each given pixel of the second image between the internal circular contour and the external circular contour (Ce2): - a sub-step of determining a polar radius and a polar angle of the given pixel, then - a sub-step of identifying at least one corresponding pixel between the internal contour and the external contour of the iris of the first image, the at least one corresponding pixel comprising a polar angle substantially equal to the polar angle of the given pixel, the at least one corresponding pixel comprising a polar radius determined as a function of the polar radius of the given pixel, the radius of the internal circular contour of the iris of the second image, and the radius of the external circular contour of the iris of the second image, then - reproduction of the parameters of at least one corresponding pixel on the given pixel.

[0015] The at least one corresponding pixel may comprise a polar radius obtained by linear or non-linear projection of the polar radius of the given pixel, the linear or non-linear projection being defined so that: - when the given pixel belongs to the internal circular contour of the iris of the second image, the corresponding pixel belongs to the internal contour of the iris of the first image, and - when the given pixel belongs to the outer circular contour of the iris of the second image, the corresponding pixel belongs to the outer contour of the iris of the first image.

[0016] The creation method may further comprise: - a fourth step of correction of defects present in the iris of the second image, and / or - a fifth step of standardizing the color and / or brightness of pixels of the second image included inside the internal circular contour.

[0017] The creation method may comprise a sixth step of printing the second image on a support.

[0018] The invention also relates to an ornamental object comprising a support and an image obtained by the creation method as defined previously, the image being printed on said support.

[0019] The invention also relates to a computer program product comprising program code instructions recorded on a computer-readable medium for implementing the steps of the creation method as defined above when said program operates on a computer.

[0020] The invention also relates to a photography installation comprising a photographic apparatus, a computer connected to the photographic apparatus and a printing apparatus connected to the computer, the computer comprising a data recording medium, on which is recorded a computer program comprising program code instructions for implementing the creation method as defined previously. Presentation of figures

[0021] These objects, characteristics and advantages of the present invention will be explained in detail in the following description of a particular embodiment made without limitation in relation to the attached figures among which:

[0022] [Fig. 1] is a block diagram of a method for creating an image comprising an iris according to one embodiment of the invention.

[0023] [Fig.2] is a schematic view of a photography installation comprising hardware and software means configured to implement the method of creating an image comprising an iris.

[0024] [Fig. 3] is a schematic view of a first image comprising an iris, the first image being obtained by means of a photographic camera.

[0025] [Fig.4] is a schematic view of an intermediate image comprising an iris, the intermediate image being obtained by reduction of the first image.

[0026] [Fig.5] is a schematic view of a second image comprising an iris, the iris comprising a circular inner contour and a circular outer contour.

[0027] [Fig.6] is a schematic view of a pixelated image comprising a circular outline.

[0028] [Fig.7] is a second schematic view of said first image. Detailed description

[0029] [Fig.l] schematically illustrates a block diagram of a method for creating an image of an iris according to one embodiment of the invention. The iris designates the colored disc of the anterior part of the eye, visible through the cornea, placed in front of the lens and pierced in its center with an orifice of variable diameter: the pupil. The iris comprises in particular radial fibers whose geometry and color is specific to each person. The method aims in particular to create a high-quality image intended to be printed on a support with a view to manufacturing an ornamental object incorporating an image of the iris. Said ornamental object therefore comprises a support on which is printed the image obtained by a method according to one embodiment of the invention. The support may for example be intended to be hung on a wall. The image represented on the ornamental object may comprise a single iris, preferably centered on the support.Alternatively, this image may include multiple irises, and possibly styling effects.

[0030] The image creation method is implemented by means of a photographic installation 1 shown schematically in [Fig.2]. The photographic installation 1 comprises a photographic camera 2, a computer 3 connected to the photographic camera 2 and a printing device 4 connected to the computer 3. The connection between the photographic camera 2 and the computer 3 and / or the connection between the printing device 4 and the computer 3 can be either a wired connection or a wireless connection. The photographic camera 2, the computer 3 and the printing device can be positioned in different locations. The printing device can for example be located in a factory. The connection between the photographic camera 2 and the computer 3 allows the transfer of digital data from the photographic camera 2 to the computer 3, in particular the transfer of a digital image obtained by the photographic camera 2 to the computer 3.The connection between the printing device 4 and the computer 3 also enables the transfer of digital data from the computer 3 to the printing device 4.

[0031] The photographic apparatus 2 is a digital apparatus, preferably installed on a support resting on the ground so as to be very stable. It comprises in particular a lens 5, a photosensitive sensor 6, a memory 7 connected to the photosensitive sensor 6 and configured to record at least one image in a digital format, and a communication interface 8 configured to exchange digital data with the computer 3. The photosensitive sensor 6 can be adapted to provide a high definition image, for example an image comprising at least fifty million pixels. The printing apparatus 4 is an apparatus configured to print an image on a physical support such as a sheet of paper, a canvas or even a panel rigid. It comprises a communication interface 10 for exchanging digital data with the computer 3, and printing means 11. The computer 3 comprises a communication interface 12 for exchanging digital data with the photographic apparatus 2 and with the printing apparatus 4, a memory 13 and a microprocessor 14. The memory 13 of the computer 3 is a data recording medium on which is recorded a computer program comprising code instructions configured to implement at least certain steps of the method for creating an image of an iris according to an embodiment of the invention. The microprocessor 14 is capable of executing this computer program.According to one embodiment, the computer 3 may be a remote server of the photographic device 2 and / or the printing device 4, the connections between the computer 3 and the photographic device 2 and / or the printing device 4 then being established by a data exchange network such as the Internet.

[0032] The method for creating an image of an iris can be broken down into several main steps. In a first step E1, a first image Iml is acquired comprising an iris Irl, a pupil Pul in the center of the iris Irl and a sclera Sel around the iris Irl, using the camera 2. The pupil Pul is generally black or at least dark in color, the sclera Sel is generally white or at least light in color. In a second step E2, an internal contour Cil and an external contour Cel of the iris Irl of the first image Iml are determined. In a third step E3, a second image Im2 of an iris is created, the second image Im2 comprising an iris Ir2 provided with an internal circular contour Ci2 and an external circular contour Ce2, the external circular contour Ce2 being centered on the internal circular contour Ci2. The iris Ir2 is constructed based on the Iris Irl of the first image Iml.The process thus aims to circularize the internal contour Cil and the external contour Cel of the iris Irl and to center these two contours relative to each other. This produces a second image Im2 whose iris has perfect geometry. This image can then more easily be subjected to various treatments, for example in order to constitute an iris database and / or in order to correct defects present in the photograph and / or in order to print this image on a support.

[0033] During the first step E1, in a first sub-step E1 1, a person P is installed so that he or she presents an eye O in front of the lens 5 of the camera 2. Advantageously, a chin rest can be used to stabilize the head of the person P. The camera is positioned and focused to take a close-up photo of the eye of this person. The image obtained by the camera 2 will thus mainly comprise the eye of the person. The camera 2 can be adjusted so that the iris I11 occupies at least half of the total height of the first image I11 and / or at least one third of the total width of the first image Iml. In addition, the camera 2 is adjusted so that the iris Irl of the first image Iml is at least roughly centered on the first image. For example, the center Cl of the first image Iml may correspond to a point of the pupil Pul. Advantageously, the camera 2 and / or the chin rest supporting the person's head are positioned on adjustment rails in order to obtain precise centering.

[0034] Advantageously, before taking the picture with the camera 2, the person's eye O is prepared in order to improve the quality of the first image Iml. In particular, in a second sub-step E12, a mechanical stress can be applied to an outline of the eye O so as to make the entire iris visible. In particular, pressure can be exerted, for example with the fingers or with a retractor, on the outline of the eye so as to separate the eyelids from the iris. Thus, the entire iris can be visible and therefore photographed by the camera 2. In a third sub-step E13, a treatment can be applied which causes a contraction of the pupil. Such a contraction can be obtained by dazzling the eye O with a series of flashes. Thus, the iris has a relatively large size, which increases the quantity of details of the iris that the camera 2 will be able to perceive.

[0035] Then, in a fourth sub-step E14, the eye is photographed using the camera 2. Advantageously, when photographing the eye O, the eye is illuminated with an artificial light source. The position and / or shape of the light source may be studied to minimize reflections of the light source on the eye. The lighting color, the lighting intensity or even the opening time of the camera 2 may be adapted to obtain the sharpest possible initial image.

[0036] Then, in a fifth sub-step E15, the photograph taken by the camera 2 is transferred to the computer 3. The computer thus acquires a first raw image Iml, i.e. one without processing. The first image Iml may comprise at least 6000 pixels in height and at least 9000 pixels in width. Each pixel of the first image may be coded in the RGB color space (i.e. the “Red-green-blue” color space). Each pixel is characterized by three parameters R, G and B corresponding respectively to the colors red, green, and blue. Each parameter R, G and B may comprise a value between 0 and 255. The first image Iml is illustrated schematically in [Fig.3] and in [Fig.7].

[0037] The iris Irl of the first image Iml has at least roughly an annular shape. The iris Irl is delimited by an internal contour Cil and by an external contour Cel. It is nevertheless observed that the contours Cil and Cel are not perfectly circumscribed. cular. Indeed, firstly, the iris of the eye being a part of a human or animal body, it naturally has an anatomical shape, distinct from a perfect geometric shape. The contours of the iris of the eye therefore have certain defects of circularity and / or concentricity. In addition, the iris Irl of the first image Iml is obtained by means of the camera 2 by a projection onto the plane of the photosensitive sensor 6 of light rays reflected on the spherical surface of the eye. The production of the photograph by the camera 2 during the first step E1 therefore systematically adds deformations to the shape of the iris Irl. These deformations can also be caused by deformations generated by the lenses integrated into the objective 5 of the camera 2 and / or by a defect in the positioning of the camera relative to the eye and / or by a defect in the orientation of the gaze when taking the photograph.The contours Cil and Cel of the first image therefore present significant circularity and concentricity defects. The invention aims precisely to correct these defects automatically, so as to obtain a second image Im2 of optimal quality which can then be used to manufacture an ornamental object.

[0038] According to the embodiment presented, the second step E2 firstly comprises a first sub-step E21 of creating an intermediate image Im3 obtained by reducing the first image Iml, or in other words by shrinking the first image Iml. The intermediate image Im3 therefore comprises a smaller number of pixels than the first image Iml. The intermediate image Im3 comprises, for example, between 100 and 200 pixels in height and between 100 and 200 pixels in width. The intermediate image Im3 nevertheless retains the same proportions as the first image Iml. The intermediate image Im3 also comprises an iris Ir3, a pupil Pu3 and a sclera Sc3. The resolution of the iris Ir3 is lower than the resolution of the iris Irl. The intermediate image Im3 can in particular be obtained by taking an average of the R, G, and B parameters of a set of pixels of the first image Iml.Next, the RGB coding is converted into CIE 1976 L*a*b* coding, also commonly referred to as CIELAB. Each pixel in the intermediate image Im3 is thus characterized by three parameters L*, a*, b*. The L* parameter designates the brightness of the pixel in question. L* takes values ​​between 0 (black) and 100 (reference white). The a* parameter represents a value on a green —> red axis. The b* parameter represents a value on a blue —> yellow axis. The a*b* standard represents a quantity of color or chromacity of a given pixel. The intermediate image Im3 is illustrated schematically in [Fig.4]. The X axis is then defined as the axis oriented along the width of the intermediate image Im3 and the Y axis as the axis oriented along the height of the intermediate image Im3.

[0039] The advantage of creating an intermediate image Im3 of smaller dimension than the first image Iml is to simplify the calculations carried out during the second step E2 and which will be explained later. Alternatively, the first substep E21 could be omitted and the following method could be applied directly to the first image Iml. However, such a method would require greater computing power. An advantage of using CIE 1976 L*a*b* coding rather than RGB coding is that the differences in values ​​of the parameters L*, a* and b* are more representative of the differences in color and brightness perceptible to the human eye.

[0040] Then, in a second sub-step E22, an internal contour Ci3 and an external contour Ce3 of the iris Ir3 of the intermediate image Im3 are determined. Advantageously, each contour Ci3 and Ce3 of the intermediate image Im3 is modeled by an intermediate ellipse, respectively referenced Ei3 and Ee3 in [Fig.4]. Each ellipse Ei3, Ee3 can be defined by four parameters, namely the coordinates of the center of the ellipse along the X and Y axes, the length of the semi-axis of the ellipse along the X axis, and the length of the semi-axis of the ellipse along the Y axis. The intermediate internal ellipse Ei3 is thus modeled by the parameters XOi, YOi, Xli and Yli, where: XOi and YOi respectively denote the coordinates along the X and Y axes of the center CEi3 of the intermediate internal ellipse Ei3, Xli denotes the length of the semi-axis of the intermediate internal ellipse Ei3 along the X axis, and Yli denotes the length of the semi-axis of the intermediate internal ellipse Ei3 along the Y axis.Similarly, the intermediate external ellipse Ee3 is modeled by the parameters XOe, YOe, Xle and Y le, where: XOe and YOe denote the coordinates along the X and Y axes of the center CEe3 of the intermediate external ellipse Ee3, Xle denotes the length of the semi-axis of the intermediate external ellipse Ee3 along the X axis, and Y le denotes the length of the semi-axis of the intermediate external ellipse Ee3 along the Y axis. Thus, the determination of the internal contour Ci3 and the external contour Ce3 of the iris Ir3 consists of determining the four parameters XOi, YOi, Xli and Yli of the intermediate internal ellipse Ei3 and the four parameters XOe, YOe, Xle and Y le of the intermediate external ellipse Ee3. The advantage of modeling the contours Ci3 and Ce3 with ellipses is to facilitate the calculations which will follow to produce the second image Im2.The modeling of the contours Ci3 and Ce3 of the iris Ir3 certainly constitutes an approximation of the real contour of this iris but this approximation proves to be a good compromise between the quantity of calculations necessary to implement the process on the one hand, and the quality of the second image Im2 which will finally be obtained on the other hand.

[0041] To determine the parameters XOi, YOi, Xli, Y li XOe, YOe, Xle and Y le one can apply an iterative algorithm of nonlinear least squares. Such an iterative method can, for example, be programmed with the C++ library “Ceres Solver”, which is freely available.

[0042] The determination of the ellipses Ei3 and Ee3 can be carried out in several sub-steps. In a first sub-step E221, a first internal ellipse Ei31 is calculated. In a second sub-step E222, a first external ellipse Ee31 is calculated as a function in particular of the first internal ellipse Ei31. Finally, in a third sub-step E223, the definition of the internal ellipse and the internal ellipse is further refined as a function of the ellipses previously calculated to arrive at the definition of the ellipses Ei3 and Ee3.

[0043] During the first sub-step E221, the four parameters defining the first internal ellipse Ei31 are therefore sought. The algorithm first defines an initial ellipse, centered on the intermediate image Ir3, and small enough to guarantee that it is completely included in the pupil Pu3. Then, the algorithm adapts the position of the center of the ellipse considered and the values ​​of its half-axes are progressively increased so as to optimize the following criteria: - the average luminance of the pixels inside the ellipse under consideration must be as low as possible. Indeed, the pixels inside the ellipse under consideration correspond to the pixels of the pupil Pu3 and must therefore be relatively dark. - the amount of color (i.e. the average of the a*b* norms) of the pixels inside the ellipse under consideration must be as low as possible. Indeed, the pixels inside the ellipse under consideration correspond to the pixels of the pupil Pu3 and must therefore be close to the color black. - the luminance L* of each pixel inside the ellipse considered must be as close as possible to the average luminance of the pixels inside the ellipse considered. - the amount of color of each pixel inside the ellipse under consideration must be as close as possible to the average amount of color of the pixels inside the ellipse under consideration. - the values ​​of the semi-axes of the ellipse considered must be as large as possible. This allows the algorithm to converge and prevents the ellipse defined by the algorithm from being an ellipse internal to the pupil. - the values ​​of the semi-axes of the ellipse considered must be fairly close to each other. Indeed, the ellipse sought still has a shape close to that of a circle. Each of these criteria can be weighted by weighting coefficients. In particular, some of the criteria can be weighted by a factor inverse to the surface area of ​​the ellipse considered so that a more dilated pupil is evaluated as well as a more contracted pupil. According to an alternative embodiment, some of the criteria mentioned above could be omitted, that is to say that their weighting coefficient in the resolution algorithm could be set to 0. At the end of the first sub-step E221, we therefore have the parameters of the first internal ellipse Ei31.

[0044] Then, during the second sub-step E222, the algorithm searches for the four parameters defining the first external ellipse Ee31. The algorithm first defines an initial ellipse, centered on the intermediate image Ir3, and large enough to ensure that it includes the entire iris Ir3. Then, the algorithm adapts the position of the center of the ellipse considered and progressively decreases the values ​​of its semi-axes so as to optimize the following criteria: - the average luminance of the pixels inside the ellipse considered and outside the first internal ellipse Ei31 must be as close as possible to the average between the estimated luminance of the pupil and a maximum luminance of the third image Im3. The maximum luminance can be equal to the maximum value of the parameter L* on all the pixels of the third image Im3. - For each pixel inside the ellipse considered and outside the first internal ellipse Ei31, the luminance L* must be as close as possible to the average luminance of the pixels inside the ellipse considered and outside the first internal ellipse Ei31. - For each pixel outside the ellipse considered and sufficiently close to the ellipse considered (i.e. at a distance less than or equal to a predefined threshold from the ellipse considered), the luminance L* must be close to the maximum luminance of the third image Im3 and the amount of color must be as low as possible. Indeed, the pixels outside the ellipse considered correspond to the pixels of the sclera Sc3 and are therefore close to the white color. - the values ​​of the semi-axes of the ellipse considered must be as small as possible. This allows the algorithm to converge and prevents the ellipse defined by the algorithm from including areas of the sclera Sc3. - the values ​​of the semi-axes of the ellipse considered must be fairly close to each other. In fact, the ellipse sought still has a shape close to that of a circle. - the center of the ellipse considered must be as close as possible to the center of the first internal ellipse Ei31 determined in step E221.

[0045] As for the first sub-step E221, each of these criteria can be weighted by weighting coefficients. According to an alternative embodiment, some of the criteria mentioned above could be omitted. At the end of the second sub-step E222, the parameters of the first external ellipse Ee31 are therefore available. During this second sub-step E222, the definition of the first internal ellipse Ei31 can possibly be refined by calculating a second internal ellipse Ei32.

[0046] Finally, in the third sub-step E223, the algorithm further refines the definition of the internal ellipse and the internal ellipse as a function of the ellipses previously calculated to arrive at the definition of the ellipses Ei3 and Ee3. The third step E223 can in particular understand the execution of the same algorithm as during sub-steps E221 and E222 but by adding additional criteria, in particular by adding a criterion relating to a gradient of brightness and / or quantity of color on either side of each ellipse Ei3 and Ee3 which must be as large as possible.

[0047] Finally, the algorithm thus manages to define the intermediate internal ellipse Ei3 and the intermediate external ellipse Ee3 which will be used in the rest of the method. As can be seen in [Fig.4], the centers CEi3 and CEe3, respectively of the ellipses Ei3 and Ee3 are not confused but relatively close to each other.

[0048] Then, in a third sub-step E23, an internal ellipse Eil is determined corresponding to the internal contour Cil of the iris Irl of the first image Iml, and an external ellipse Eel is determined corresponding to the external contour Cel of the iris Irl of the first image Iml. The internal ellipse Eil can be simply calculated applying an enlargement of the previously calculated intermediate internal ellipse Ei3. Similarly, the external ellipse Eel can be simply calculated applying an enlargement of the previously calculated intermediate external ellipse Ee3. Said enlargement is then an operation inverse to the reduction carried out during the previously described step E21. This step can be easily carried out by multiplying the different parameters defining the ellipses Ei3 and Ee3 by a predetermined factor, calculated as a function of the reduction factor used during the step E21.

[0049] The third step E3 is now described, during which the second digital image Im2 is created, comprising an iris Ir2. The iris Ir2 comprises an internal circular contour Ci2 and an external circular contour Ce2, the external circular contour Ce2 being centered on the internal circular contour Ci2. The second image Im2 is a digital image. It comprises a high resolution, compatible with printing this image on a medium. The second image may in particular comprise at least six million pixels. The second image is illustrated schematically in [Fig.5].

[0050] The second image Im2 being a digital image, it is made up of pixels arranged according to a matrix. Each pixel preferably comprises a square shape. The position of a pixel can be precisely defined as the position of the center of its square shape. Thus, the contours Ci2 and Ce2 are each defined by a set of pixels. Due to the matrix arrangement of the pixels, the pixels forming the contours Ci2 and Ce2 are not rigorously positioned on a perfect circle. Thus by "circular contour", it is understood that the contours Ci2 and Ce2 are defined so as to be as close as possible to a circle while taking into account the matrix nature of a pixelated image. In other words, it is possible to define an internal virtual circle and an external virtual circle concentric with the internal virtual circle such that: - all pixels of the second image whose center is positioned strictly at outside the inner virtual circle and strictly inside the outer virtual circle belong to the iris Ir2, - all pixels whose center is positioned inside the inner virtual circle or on the inner virtual circle do not belong to the iris Ir2, and - all pixels whose center is positioned outside the external virtual circle or on the external virtual circle do not belong to the iris Ir2. The parameters of a pixel of the second image Im2 whose contour is crossed by the internal virtual circle or by the external virtual circle can be weighted according to the surface of this pixel located inside or outside the virtual circle considered.

[0051] [Fig.6] illustrates this principle by considering a very limited number of pixels so as to make visible a circular contour in the form of "stair steps". The matrix structure of an image is schematized by a grid Q. A circular contour CC is represented with a solid line. The pixels positioned inside the circular contour CC or on the circular contour CC are identified by Pxa. The pixels positioned strictly outside the circular contour CC are identified by Pxb. In practice, since the number of pixels of the second image Im2 is very high, the circular contour in the form of "stair steps" is imperceptible to the naked eye.

[0052] Advantageously, the ratio of the diameter Di of the internal circular contour Ci2 to the diameter De of the external circular contour Ce2 is equal to a predetermined value, for example a value between 0.2 and 0.3. Thus, all the irises Ir2 of the second images Im2 obtained by the method according to the invention comprise the same proportions. The second image Im2 is therefore independent of the state of dilation of the pupil of the person's eye at the time the photograph is taken. This also makes it possible to construct a standardized database comprising all the images obtained by the method according to the invention. This facilitates an operation of searching for common characteristics and / or differences between different irises in the database.

[0053] Each given pixel Px2 of the second image between the inner circular contour Ci2 and the outer circular contour Ce2 is defined by means of a projection of at least one corresponding pixel Pxl of the first image Iml. The at least one corresponding pixel Pxl is between the inner contour Cil and the outer contour Cel of the iris Irl of the first image. The at least one corresponding pixel Px2 occupies a position in the iris Irl of the first image Iml corresponding to the position of the pixel Px2 in the second image. In other words, each pixel Px2 of the iris Ir2 of the second image Im2 is defined by identifying in the iris Irl of the first image Iml one or more pixels Pxl whose position corresponds substantially to the position of the pixel Px2 in the iris Ir2.

[0054] Advantageously, the position of each pixel Px2 of the second image is defined Im2 in polar coordinates. For this, we use a reference frame whose origin 02 corresponds to the center of the contours Ci2 and Ce2. The position of a pixel Px2 is thus characterized by a radius R2 and an angle A2. The radius R2 corresponds to the distance of the pixel Px2 to the origin 02. The angle A2 corresponds to the angle formed between the segment [0Px2] and a segment oriented along the width of the second image Im2, as shown schematically in [Fig.5].

[0055] Similarly, the position of each pixel Pxl of the first image Iml is defined in polar coordinates. For this, a reference frame is used whose origin 01 corresponds to the center of the ellipse Eil or to the center of the ellipse Eel, or to the middle of the segment formed between the center of the ellipse Eil and the center of the ellipse Eel. As the eccentricity of the ellipses Eil and Eel is relatively small, the different means of defining the center 01 of the reference frame of the first image lead to substantially the same result. The position of a pixel Pxl is thus characterized by a radius RI and an angle AL. The radius RI corresponds to the distance of the pixel Pxl from the origin 01. The angle Al corresponds to the angle formed between the segment [OPxl] and a segment oriented along the width of the first image Iml, as shown schematically in [Fig.7].

[0056] To construct the iris Ir2 of the second image Im2 by projection, we can proceed in the following manner for each pixel Px2 included between circular contours Ci2 and Ce2. First, in a first sub-step E31, the polar radius R2 and the polar angle A2 of the pixel Px2 considered are determined. For example, trigonometric formulas can be applied to determine the parameters A2 and R2 of a pixel from its Cartesian coordinates. The value of R2 is therefore between Di / 2 and De / 2.

[0057] Then, in a sub-step E32, at least one pixel Pxl is identified between the internal contour Cil and the external contour Cel of the iris Irl of the first image Iml, the position of which corresponds to the position of the pixel Px2 considered in step E31. On the one hand, the corresponding pixel Pxl comprises a polar angle Al substantially equal to the polar angle A2 of the pixel Px2. On the other hand, the corresponding pixel Pxl comprises polar radius RI determined as a function of the polar radius R2 of the pixel Px2, the radius Di / 2 of the internal circular contour Ci2, and the radius De / 2 of the external circular contour Ce2.

[0058] More precisely, we can determine the polar radius RI of the corresponding pixel Pxl by respecting the following conditions: . - when the pixel Px2 belongs to the internal circular contour Ci2 of the iris Ir2 of the second image Im2, the corresponding pixel Pxl belongs to the internal contour Cil of the iris Irl of the first image Iml. - Similarly, when pixel Px2 belongs to the external circular contour Ce2 of the iris Ir2 of the second image Im2, the corresponding pixel Pxl belongs to the external contour Cel of the iris Irl of the first image Iml.

[0059] According to one embodiment, it is possible to identify the pixel Pxl of the first image which satisfies the following conditions: On the one hand: Al = A2, and On the other hand: RI = [(R2 - Di / 2) / (De / 2-Di / 2)]x(Rle - Rli)+Rli where: - De / 2 denotes the radius of the external circular contour Ce2; - Di / 2 denotes the radius of the internal circular contour Ci2; - Rli denotes the length of the segment [01 Pii], Pii being the point of intersection of the line (OlPxl) with the ellipse Eil; - Rie denotes the length of the segment [OlPel], Pel being the point of intersection of the line (OlPxl) with the ellipse Eel. RI is thus an affine function of R2. A tolerance margin can be defined to select the pixel(s) Pxl of the iris Irl satisfying these conditions. Thus, several pixels Pxl of the iris Irl can possibly be associated with a pixel Px2 of the second image

[0060] Once the pixel Pxl of the first image is identified, a third sub-step E31 is carried out in which the RGB parameters of the at least one corresponding pixel Pxl are reproduced on the given pixel Px2. In the event that several pixels of the first image satisfy the conditions mentioned above, the pixel Px2 can be defined by taking an average of the RGB parameters of this set of pixels of the first image. This average can possibly be weighted according to the distance of the pixel Pxl from the point of polar coordinates (A1, R1).

[0061] Since the function calculating the polar radius RI as a function of the polar radius R2 is an affine function, the method explained above constructs the iris Ir2 by a linear projection. This projection therefore preserves as much as possible the proportions of the iris Irl of the first image to construct the iris Ir2 of the second image. Advantageously, and according to an alternative embodiment of the invention, the formula of the function calculating the polar radius RI as a function of the polar radius R2 can also be adapted so as to produce a non-linear projection. A non-linear projection can be configured to enhance parts of the iris Irl of the first image which are located in specific crowns. In particular, a non-linear projection can be used to enhance the parts of the iris Irl which are closest to the internal contour Cil.These parts of the iris are usually rich in anatomical detail and are therefore advantageously highlighted. Therefore, the use of a non-linear projection can help to highlight certain particularities of the iris.

[0062] Finally, during the third step E3, the same projection operation is repeated for all pixels Px2 whose position is between contours Ci2 and Ce2. This results in the construction of an iris Ir2 very faithful to the iris Irl of the first image, but advantageously presenting a circular internal contour and a circular external contour centered on the circular internal contour. Such an image presents an optimal visual quality. In addition, this image can then be more easily processed to carry out various operations including defect correction treatments and / or comparisons of the iris Ir2 with other irises stored in a database.

[0063] Following the third step E3, the method can be completed by a fourth step E4 during which corrections are made to any defects present on the iris Ir2. These defects can in particular be reflections linked to the lighting of the eye during the initial photographing, in step E14. For this, it is possible in particular to carry out an “inpainting” technique, that is to say a technique for filling in a missing part of an image based on the parts neighboring the missing part.

[0064] Then, in a fifth step E5, the color and / or brightness of pixels of the second image Im2 included inside the internal circular contour Ci2 are standardized. In particular, a third circular contour can be defined, concentric with the circular contours Ci2 and Ce2, and whose diameter is strictly less than the diameter Di of the internal circular contour Ci2. All the pixels included inside the third internal circular contour can be changed to black, with zero brightness. The pupil will thus appear perfectly black on the second image Im2, even though it appeared gray on the first image Iml. The contrast of the second image Im2 is thus improved. Between the third circular contour and the internal circular contour Ci2, a transition zone can be created.The pixels in the transition area may comprise a shade of gray that transitions smoothly between the black, non-bright pixels within the third circular outline and the brighter iris pixels Ir2. A step analogous to the fifth step E5 may also be implemented to standardize the color and / or brightness of pixels in the second image Im2 positioned outside the outer circular outline Ce2. In addition, various artistic effects may still be applied to the image to further customize it.

[0065] Finally, in a sixth step E6, the previously obtained image is printed on a support by means of the printing apparatus 4 so as to form a single ornamental object comprising a high-quality representation of a person's iris. The method which has just been described has the advantage of being completely automated or automatable. The implementation of the method does not require the manual intervention of an image processing expert. The method can be executed quickly by the computer 3. A person can therefore more quickly obtain the ornamental object made from a photograph of his or her iris. Another advantage of the present invention is that the iris printed on the support is not strictly identical to the real iris of the person whose eye was photographed. This makes it possible to preserve a certain confidentiality of a person's physiological data. In particular, the ornamental object produced cannot be used in iris recognition authentication systems.

Claims

Claims

1. A method of creating an image comprising an iris, the creation method comprising: - a first step (El) of acquiring a first digital image (Iml) comprising an iris (Irl), by means of a camera (2), then - a second step (E2) of determining an internal contour (Cil) and an external contour (Cel) of the iris of the first image, then - a third step (E3) of creating a second digital image (Im2) comprising an iris (Ir2), the iris of the second image comprising an internal circular contour (Ci2) and an external circular contour (Ce2), the external circular contour being centered on the internal circular contour, each given pixel of the second image between the internal circular contour and the external circular contour being defined by means of a projection of at least one corresponding pixel of the first image,the at least one corresponding pixel being between the inner contour and the outer contour of the first image.,

2. Creation method according to the preceding claim, characterized in that the second step (E2) comprises a sub-step (E23) of determining an internal ellipse (Eil) corresponding to the internal contour (Cil) of the iris (Irl) of the first image (Iml), and / or a sub-step of determining an external ellipse (Eel) corresponding to the external contour (Cel) of the iris (Irl) of the first image (Iml).

3. Creation method according to one of the preceding claims, characterized in that the second step (E2) comprises: - a first sub-step (E21) of creating an intermediate image (Im3) comprising an iris (Ir3), the intermediate image being obtained by reducing the first image (Iml), then - a second sub-step (E22) of determining an internal contour (Ci3) and an external contour (Ce3) of the iris of the intermediate image, then - a third sub-step (E23) of calculating the internal contour (Cil) and the external contour (Cel) of the iris (Irl) of the first image (Iml) by enlarging respectively the internal contour of the iris of the intermediate image and the external contour of the iris of the intermediate image.

4. Creation method according to the preceding claim, characterized in that that said second sub-step (E22) comprises: - a sub-step (E221) of determining an intermediate internal ellipse (Ei3) corresponding to the internal contour (Ci3) of the iris (Ir3) of the intermediate image (Im3), then - a sub-step (E222) of determining an intermediate external ellipse (Ee3) corresponding to the external contour (Ce3) of the iris (Ir3) of the intermediate image (Im3).

5. Creation method according to the preceding claim, characterized in that the parameters defining the intermediate internal ellipse (Ei3) and the intermediate external ellipse (Ee3) are determined by an iterative method of non-linear least squares.

6. Creation method according to one of the preceding claims, characterized in that the first step (El) comprises: - a sub-step (Eli) of adjusting the camera so that a height of the iris (Irl) of the first image (Iml) is at least equal to half a height of the first image and / or so that a width of the iris (Irl) of the first image (Iml) is at least equal to one third of a width of the first image and / or so that the center (Cl) of the first image (Iml) is included inside the internal contour (Cil) of the iris (Irl) of the first image, and / or - a sub-step (E12) of applying a mechanical stress to a contour of the eye (O) of a person (P) so as to make the entire iris of this eye visible, and / or - a sub-step (E13) of a treatment causing a contraction of the pupil of the eye (0) of a person (P).

7. Creation method according to one of the preceding claims, characterized in that a ratio of the diameter (Di) of the internal circular contour (Ci2) to the diameter (De) of the external circular contour (Ce2) is equal to a predetermined value, for example a value between 0.2 and 0.

3.

8. Creation method according to one of the preceding claims, characterized in that the third step (E3) comprises for each given pixel (Px2) of the second image (Im2) between the internal circular contour (Ci2) and the external circular contour (Ce2): - a sub-step (E31) of determining a polar radius (R2) and a polar angle (A2) of the given pixel, then - a sub-step (E32) of identifying at least one corresponding pixel (Pxl) between the internal contour (Cil) and the external circular contour (Ce2) external (Cel) of the iris (Irl) the first image (Iml), the at least one corresponding pixel comprising a polar angle (Al) substantially equal to the polar angle (A2) of the given pixel, the at least one corresponding pixel comprising a polar radius (RI) determined as a function of the polar radius (R2) of the given pixel, the radius (Di / 2) of the internal circular contour (Ci2) of the iris of the second image, and the radius (De / 2) of the external circular contour (Ce2) of the iris of the second image, then - reproducing the parameters of the at least one corresponding pixel (Pxl) on the given pixel (Px2).

9. Creation method according to the preceding claim, characterized in that the at least one corresponding pixel (Pxl) comprises a polar radius (RI) obtained by linear or non-linear projection of the polar radius (R2) of the given pixel (Px2), the linear or non-linear projection being defined so that: - when the given pixel (Px2) belongs to the internal circular contour (Ci2) of the iris (Ir2) of the second image (Im2), the corresponding pixel (Pxl) belongs to the internal contour (Cil) of the iris (Irl) of the first image (Iml), and - when the given pixel (Px2) belongs to the external circular contour (Ce2) of the iris (Ir2) of the second image (Im2), the corresponding pixel (Pxl) belongs to the external contour (Cel) of the iris (Irl) of the first image (Iml).

10. Creation method according to one of the preceding claims, characterized in that it further comprises: - a fourth step (E4) of correcting defects present in the iris (Ir2) of the second image (Im2), and / or - a fifth step (E5) of standardizing the color and / or the brightness of pixels of the second image (Im2) included inside the internal circular contour (Ci2).

11. Creation method according to one of the preceding claims, characterized in that it comprises a sixth step (E6) of printing the second image (Im2) on a support.

12. Ornamental object comprising a support and an image (Im2) obtained by the creation method according to one of the preceding claims, the image being printed on said support.

13. A computer program product comprising program code instructions recorded on a computer-readable medium for implementing the steps of the creation method according to any one of the claims 1 to 11 when said program runs on a computer.

14. Photography installation (1) comprising a photographic camera (2), a computer (3) connected to the photographic camera (2) and a printing device (4) connected to the computer, the computer comprising a data recording medium, on which is recorded a computer program comprising program code instructions for implementing the creation method according to one of claims 1 to 11.

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