CA2834978A1 - Method for the production of an iridescent image, the resulting image, device comprising same and associated program - Google Patents

Abstract

The invention relates to a method for manufacturing an iridescent image (II) from a reference image (IR), the iridescent image (II) comprising an optical selector (SO) selected from the group comprising a array of cylindrical lenses, an array of spherical lenses and a parallax barrier, the method comprising the steps of - creating a period suitable for the optical selector (SO) and the reproduction system used, - creating a periodic image (IP) filled repeatedly according to said period, - creation of a scattered image by application of a dispersion filter to the periodic image (IP) in which the geometric position of the pixels of the periodic image (IP) is modified as a function of the values of the corresponding pixels in the reference image (IR), - relating the dispersed image (ID) thus created to the optical selector (SO). The invention also relates to the dispersed and iridescent images obtained from such a method, and a device comprising them as well as to an associated program.

Description

METHOD FOR MANUFACTURING AN IRIDESCENT IMAGE, IMAGE OBTAINED
AND DEVICE COMPRISING SAME, PROGRAM.
TECHNICAL FIELD OF THE INVENTION
The invention relates to the field of creating iridescent images.
The effect of iridescence occurs when our eyes, distant from each other, perceive from one and the same object colors and / or luminous intensities different. Such images are for example used to achieve a display more aesthetic on product packaging. Thus, the result is effects eye-catching and striking for the consumer.

An image of this type can also be provided on a credit card or telephone, a window, a decoration, a press kit, a map of wishes, a garment or shoe mark, or an element of communication such as a commercial card.
STATE OF THE PRIOR ART

[0003] Many methods of creating moiré images have been proposed. Thus, EP 1 147 878 discloses a moiré pattern or iridescent made from a printed matrix of lenticular elements on at least one surface of a substrate. This device does not turn out fully satisfactory. Indeed, this document does not allow to realize easily an iridescent image from a given reference image such as a drawing, a photograph or a text.
SUMMARY OF THE INVENTION

The invention aims to overcome the disadvantages of the state of the art mentioned above.

To do this, is proposed a method of manufacturing an image iridescent from a reference image, where the iridescent image includes a optical selector selected from the group consisting of a lens array cylindrical, a network of spherical lenses and a parallax barrier.

According to a first aspect of the invention, the method comprises the steps - creation of a period adapted to the optical selector and the system of reproduction used, - creating a periodic image repetitively filled according to said period, of creating a dispersed image by applying a dispersion filter (displacement mapping) to the periodic image in which the position Geometry of the pixels of the periodic image is modified according to the values corresponding pixels in the reference image, the scattered image thus created with the optical selector.

[0007] By period adapted to an optical selector, a succession repeated elements such as pixels of an image, the repetition of which matches optical selector audit used. A period adapted to a system of image production, a period whose resolution and number of colors can be reproduced by said given image production system

[0008] By periodic image is meant an image comprising a succession of elements repeated according to a given period. These elements repeated give their colors to the effects of iridescence in the image iridescent obtained.
[000910n refers to a reference image, an image representing colors, what we perceive of the iridescent image. The image of reference can represent for example, a drawing, a picture or a text.
By optical selector means an element connected with the scattered image to allow the observer to perceive the effects iridescence. Such an optical selector is for example a lens array linear still called lenticular network that includes lenses cylindrical longitudinal. Such an optical selector can also be a network of lentils spherical or a parallax barrier. In general, a barrier of parallax includes lines, circles, ellipses, squares, rhombs, zigzags etc, whose size and frequency are preferably fixed, and which may be printed, engraved, molded, sandblasted or hot-laid on or in a substrate transparent or translucent for example PVC, glass, plexiglass (Polymethylmethacrylate) ... thus presenting a periodic structure of transparent, translucent or opaque areas. The optical selector can outraged have reserve areas (mask) if you want the image iridescent does not show an iridescence effect on its totality.
Regarding the reproduction of the scattered image, it is necessary to adapt precisely the size of said dispersed image according to the selector optical used and the average observation distance defined according to the application considered. This is done according to the state of the art well known (pitch adjustment) in connecting an abacus with the optical selector in the same conditions that the final relationship. The abacus consists of an image periodic with a basic period, pixels black white pixels, and contains of the areas with different size changes. The right one is the one who allows a transition from black to white very fast when the observer is placed at the average distance defined and moves slightly perpendicular to the lenses.
[001210n means by formatting an image, the realization of this picture preferably by computer means.
Connecting the scattered image with the optical selector so to obtain the iridescent image may consist of a reproduction of the image scattered shaping preferably on the opposite optical selector face to the viewer, or a counter-collage on this face by providing space necessary between the optical selector and the scattered image for reasons of focal explained below. The scattered image formatted can also be reproduced on one side of the optical selector by engraving, molding, sanding or any other method allowing such reproduction. Thus, the implementation relationship consists for example of a reproduction such as an engraving impression, molding, sanding. In the case of an engraving in a glass block, the image scattered is etched behind the parallax barrier, itself engraved, in leaving a detailed focal distance further between the two.
In a preferred embodiment, the method further comprises a step application of a blur on all or part of the reference image, before step applying said dispersion filter.
According to another preferred variant, the step of creating the image periodical and / or the step of creating the scattered image is carried out at way at least one mask covering at least a part of the periodic image and / or the scattered image and / or the optical selector.
In general, the color mode of the period is adapted to the reproduction system used and can represent either a single layer of color, in bitmap or gray level, three layers red green blue, is four layers cyan magenta yellow black. Advantageously, the period includes either a single color layer, in bitmap or grayscale, or two layers of colors whose clearest is a constant value on all of that period.
In the case of a shaping of a dispersed image comprising vector data, for example for laser engraving in a glass block, the previously described method in bitmap mode can also be adapted to vector mode by applying the dispersion filter to the image vectors instead and place pixels of the image, or by vectorizing the scattered image.
[00181Preferentially, the modification of the position of the pixels has a maximum amplitude between 0.5 and twice the size of a period.
A
higher amplitude creates a lot of folds and can also be interesting for aesthetic purposes.
[00191In an interesting way, the size of the periodic image and that of the image are proportional.

[0020] Advantageously, the color mode of the periodic image represents either a single layer in gray level or three layers red green blue.
According to a preferred embodiment, the resolution of the image of reference is less than or equal to the resolution of the periodic image.
According to a preferred variant of the method according to the invention, the selector optics is selected from the group consisting of a lens array linear and a parallax barrier consisting of lines, and the function of dispersion is applied on an axis substantially perpendicular to the lenses linear or line.
According to another preferred embodiment, the optical selector is a barrier of parallax, and a second scattered image is created from the image of reference by applying a second dispersion filter to an image periodically adapted to said parallax barrier, and the step of relationship of the two scattered images to create the iridescent image includes a reproduction of said scattered images on either side or in a substrate transparent or translucent so the parallax barrier is incorporated of one of the two scattered images in combination with the transparent substrate or translucent.
The invention also relates to a dispersed image obtained from of a reference image, and intended to be observed through a selector characterized in that the scattered image is shaped by position pixels modified by an application of a dispersion filter in which the geometric position of the pixels of a periodic period image determined, is modified according to the values of the corresponding pixels in the reference image.
Another object of the invention consists of an iridescent image comprising the scattered image described above, put in relation with a selector optic selected from the group consisting of a lens array linear, a network of spherical lenses, a parallax barrier.

[0026] Preferably the dispersed image and the iridescent image according to the invention are obtained by the method described above.
[0027] Advantageously, the modification of the position of the pixels has a amplitude between 0.5 and twice the size of a period. An amplitude higher creates a lot of folds and can also be interesting for purposes aesthetic.
Another object of the invention consists in a device characterized in what he comprises a dispersed image as described above or obtained by the method described above, put in relation with an optical selector selected from the group consisting of a linear lens array, a network spherical lenses, and a parallax barrier.
Such a device may be, without limitation, a card bank or telephone, a window, a packaging, a decoration, a marking of clothing or shoe, a ruler, a key ring, a bottle, a bottle, a plate, a glass, a vase, a shade, a box, an engraved block of glass, a communication element such as a commercial map, a press kit, a brochure, a sign, an industrial marking, a publishing product such a poster, a postcard, a greeting card, a bookmark, a cover of a binder, a book, a notebook or a notebook, such a jewel one bracelet, a pendant, a brooch, the dial of a watch or a clock, tile or glazing.
Another object of the invention is a secret image comprising a dispersed image as described above, or obtained by the process previously described, intended for one or more observers, characterized in that the period and / or the appropriate optical selector (SO) are known and / or held exclusively by one or more observers given in order to recreate the corresponding iridescent image.
Another object of the invention is an anti-security image.
counterfeiting comprising a dispersed image as described above or obtained by the method described above, or an iridescent image such as previously described or obtained by the method described above.
Another object of the invention is a product-program computer capable of being loaded into the memory of a control unit such as a computer, comprising means for implementing the method previously described.
BRIEF DESCRIPTION OF THE FIGURES
[0033] Other characteristics, details and advantages of the invention will come out reading the description which follows, with reference to the appended figures, which illustrate:
Figure 1A, a periodic image for creating an image iridescent according to the invention;
Figure 1B, the period of the image of Figure 1A, consisting of 5 black pixels and 5 white pixels.
Figure 2, a reference image;
FIG. 3, a dispersed image resulting from the dispersion filter applied to the periodic image of FIG. 1A as a function of the reference image of Figure 2 FIG. 4, an iridescent image comprising the dispersed image of the FIG. 3 relating to a network of linear lenses, and observed at different successive angles A1 to A6 and covering the whole field angle of the optical selector;
FIG. 5 is a diagram of a perspective view of a scattered image connection with a network of linear lenses;
FIG. 6, a diagram of the scattered image and the lens array linear of Figure 5 in front view.
For the sake of clarity, identical or similar elements are identified by identical reference signs on all the figures.
DETAILED DESCRIPTION OF THE EMBODIMENTS

[00351By referring to FIGS. 1A to 2, the dispersed image according to the invention is advantageously carried out from a periodic IP period image determined and an IR reference image, by means of a program computer graphics processing.
the iridescent image. Such a reference image is for example a photo, a reason, a text or the like. It preferably presents the same proportions as the periodic image IP.
The periodic image IP used comprises a period of five pixels black The periodic image IP will give its colors to the iridescent image -II-.
In general, the period defines the colors that will be perceived in the iridescent image iridescence effects. Interestingly, the invention is carried out without requiring a marking of the colors to be printed, and the According to another variant not shown, the invention is realized with color tracking means, and the period includes as many layers WO 2012/150426

9 PCIYFR2012 / 051313 of color that the reproduction system used allows, typically in cyan black yellow magenta for printing.
Referring to FIGS. 3 and 4, the dispersed image ID obtained comprises the pixels Ti and T2 of the periodic image which have been moved by applying a dispersive filter (displacement mapping) detailed below. Move is here perpendicular to the network of longitudinal lenses, and to the left.
The scattered ID image is related to a network of lenses cylindrical SO adapted to make an iridescent image -II-. The application of a blur to the reference image makes it possible to visualize a characteristic border bc around drawing in the iridescent image. When there is no application of blur in the reference image of the same resolution as the periodic image, the image scattered shows sharp breaks in periodic elements, and the image iridescent does not show a characteristic border essentially because the absence of blur in the reference image.
[0042] In addition, the iridescent image II shows iridescent visual effects clear, and dark according to the angle of the observation, and the area of the observed image as shown in Figure 4. We can see the effect of iridescence on the figure 4 by observing two successive images, for example Al and A2, so stereoscopic for example in cross-vision or using a stereoscope.
The reference image IR of FIG. 2 comprises a text composed of five masks M1 to M5, a text 1 not blurred, a text 2 blurred and a photo 3 in shades of grey.
According to a preferred variant, it is possible to use a mask before application dispersion filter (as in FIGS. 1A, 2 and 3), the image periodic was created by filling it with the period repetitively by doing use five masks to provide non-periodic reserve areas that will not show any iridescence effect. The corresponding areas in the image IR reference will be fulfilled advantageously with the corresponding color at a zero displacement during the application of the dispersion filter.

WO 2012/150426

10 PCT / FR2012 / 051313 According to another preferred variant, it is also possible to make use of masks to fill the periodic image with areas of color periods different (not shown) and this before the application of the filter of dispersion.
The use of a mask (not shown) may also consist of come to paste elements in the scattered image before its reproduction, -it is a complete replacement of the area of the scattered image, -if with opacity value, -so still using a merge mode.
These last two uses make it possible to obtain on a photo a mix of the original photo and the iridescence effect.
The use of a mask (not shown) may also consist of to apply a colorimetric filter on the periodic image or the image dispersed.
FIGS. 5 and 6 illustrate an example of linking a network of SO lenses and a scattered ID image. The scattered ID image includes pixels T1, T2, and is intended to be for example printed on the opposite side of network of lenses SO or laminated on it. A spacing -d- must to be provided between the lens array and the scattered image according to the distance focal cylindrical lenses.
[0049] The manufacture of a linear parallax barrier may comprise the steps :
- creation of a period whose number of pixels and the resolution depends on the desired resolution of the barrier, for example a linear barrier of 120 LPI
can be realized with a period of 10 pixels in 1200 DPI according to the relation No. of pixels in the period = Resolution of the period / Resolution of the fence, WO 2012/150426

11 PCT / FR2012 / 051313 - filling a part of the period with black pixels, for example 50%
black pixels as in Figure 1B
of creating a periodic image, of the same resolution as said period and of the same size as the desired parallax barrier, filled in repetitive according to said period, - shaping said periodic image using a substrate transparent translucent and a suitable rendering system which makes it possible to obtain zoned opaque for each black pixel of said periodic image.
Thus, alternatively, before shaping it can also be applied a dispersion filter on said periodic image representing the barrier of parallax in order to spread the displacements both on the barrier of parallax and on the scattered image.
The linking consists of assembling the scattered image ID with the optical selector SO to obtain the iridescent image II. When the selector optical SO consists of lenses (linear or spherical) image dispersed ID must be substantially at the focal length of said lenses. In general the thickness of the commercially available lens networks responds to the this requirement so that the image must be on the opposite side to the lenses (see figures 5 and 6) When the optical selector SO is a parallax barrier appropriate to keep a distance between the barrier and the ID. To obtain an effect of iridescence, that is to say, so that both eyes of the observer perceive of the different images, care should be taken to ensure that this distance is not too much small.
Example 1: network of linear lenses:
In the case of a linear array of 120 lenses per inch and a system of reproduction in 1200 dpi, the adapted period will be in 1200 dpi and will include 10 WO 2012/150426

12 PCT / FR2012 / 051313 online pixels that can for example be arranged in one of the ways following:
- 5 black pixels and 5 white pixels;
a gradient from white to black over the 10 pixels;
a gradient from white to black from pixel 1 to pixel 5 and black to white from pixel 6 at pixel 10.
Example 2: Network of spherical lenses:
In the case of a spherical array of 120 lenses per inch and a system of reproduction in 1200 dpi, the adapted period will be 1200 dpi and will be a square 10x10 pixels that can be arranged as follows:
from black for zones (1,1) to (5,5) and (6,6) to (10,10) and - white for other areas.
To obtain a period with a gradient, the pixels can be arranged as follows a gradient from white to black from (1,1) to (1,10) and from (1,1) to (10,1);
a gradient from black to white from (1.10) to (10.10) and from (10.1) to (10.10);
the inner pixels of (2,2) to (9,9) being filled by interpolation bilinear pixels of the contour thus defined;
[0056] Still to obtain a period with a gradient one can create a circle Black blur in the center of the square leaving the white outline pixels.
The creation of the iridescent image is done by a method which comprises of the steps of:

(1) characterize the geometric and repetitive structure of the optical selector, and optionally, to manufacture the optical selector for example in the manner previously detailed for a parallax barrier.
(2) create the period whose size (that is, the number of XY pixels) depends on characteristics of the optical selector and the resolution of the reproduction used to reproduce the scattered image, (3) create the IP periodic image by filling it with the period so repetitive. Optionally, you can use masks to have several zones of different color periods or non-periodicals which will not show any iridescence effects, or for apply a color filter, (4) creating the IR reference image comprising elements such as a drawing, a photo, text, pattern, etc.
(5) generating a scattered ID image by applying a dispersion filter to the image periodic IP to move all the pixels according to the values of pixels corresponding in the reference image, according to the formula ID = DispMap (IP, IR) (6) realize the iridescent image -II- by relating the scattered image ID
with the optical selector which may consist of a direct impression on the face optical selector opposite the observer, an impression followed by a sticking against this face, any other form of reproduction.
[00581 The Displacement Mapping Filter requires for each pixel (Xip, Yip) of the periodic image IP calculation of the coordinates (Xir, Yir) of its pixel reference in the IR.
[0059] When the periodic image IP and the reference image IR have the same cut and the same resolution that is to say the same number of pixels horizontally and to the vertically, the coordinates of the respective pixels are equal, depending on the formula :

XMAXir = XMXA9 Xir = Xip {and YMAXiFYMAXip Yir = Yip where XmAxir, YmAxir and XmAxip, YmAxip are the respective sizes (in and ordinate) IR and periodic reference images IP and the Xir coordinates, Yir, Xip, Yip are integers.
Similarly, when the periodic image IP and the reference image IR are of different size, the coordinates of the reference pixels are calculated following the formula mAxir4XmAxip Xi r = Xip. (XmAxir / XmAxip) and => and YmAxirei'mpocip Yir = Yip. (YmAxir / YmAxip). In that case, the coordinates Xir, Yir are real numbers and the corresponding value is calculated by bilinear interpolation of the values of neighboring whole pixels.
As regards the calculation of the displacement value, the value of a pixel in the reference image IR represents a color such as a gray level, or still three values red green blue. This is to match this color a pixel displacement value. To do this, it is necessary to limit the maximum displacement (Bmax) which will preferably be between 0.5 and 2 times the cut of a period. When the color varies from its minimum to its maximum value displacement can vary from 0 to the maximum defined limit (Bmax) or from -Bmax / 2 to + Bmax / 2.
The means for producing the dispersed image intended for production of iridescent image according to the invention are preferably implemented by computer, using image processing software. The scattered image obtained is then generated and put in relation with an optical selector of the previously developed.

In the case of using a lenticular network consisting of lentils cylindrical or parallax barrier consisting of lines these have to be vertical to obtain the best iridescence effect. However, he may be interesting to tilt lines or lenses from an alpha angle of 25 to 65 degrees. The iridescence effect is then always preserved and the support present in plus the benefit of being animated when it is rotated up and down.
There are two ways to proceed:
[0065] The first comprises a rotation of the periodic IP image of alpha degrees and then filling the period and then rotating the image of reference IR of alpha degrees, then creating the scattered ID image by application of dispersion filter creating a horizontal displacement (dx) and then a relation of the scattered image ID with the optical selector SO. The image is will then look at it by reducing it by less than alpha degrees.
The second way of proceeding includes filling the image periodic IP with the inclined period of alpha degrees and then the creation of the image scattered ID by applying the dispersion filter creating a displacement (dx, dy) perpendicular to the cylindrical lenses or the lines of the barrier of parallax, before formatting, and the relation of the scattered image ID
with the optical selector SO itself inclined at an angle of alpha degrees.
Note that in the case of a parallax barrier placed in relation with a scattered image one can choose to place one or the other before or behind. The formatting will take this choice into account.
In another variant of the invention, it is also possible to obtain a iridescent image as follows. We calculate a first image scattered, with a displacement value ranging from 0 to + BMax; then we calculate a second scattered image with a displacement value ranging from 0 to ¨Bmax;
and we put in relation these two images on both sides of a substrate transparent or translucent so that the scattered image closest to the observer play the role of optical selector in combination with the transparent substrate or translucent chosen in a suitable size. In the case of an engraving in a block of glass, the image is reproduced inside the glass block, at the distance mentioned above. In another variant of the invention implemented with a parallax barrier, you can also get an image iridescent as follows. A first, preferably dispersed image is calculated from the same reference image, with a displacement value varying of 0 to + BMax; then we compute a second image dispersed preferably from a second periodic image adapted to said parallax barrier, with an opposite displacement value ranging from 0 to ¨Bmax; and we put in relation these two images on either side of a transparent or translucent substrate of so that the scattered image closest to the observer plays the role of optical selector in combination with the transparent or translucent substrate chosen in a suitable size. In the case of an engraving in a block of glass, the two scattered images are reproduced inside the glass block, the distance mentioned above. Such a second adapted periodic image to a parallax barrier advantageously comprises an alternation of pixels black and white pixels.
The invention is not limited to the embodiments described below.
above.
For example, many combinations can be considered without leaving of the scope of the invention.

Claims (14)

1. Method for producing an iridescent image (II) from an image of reference (IR), the iridescent image (II) comprising an optical selector (SO) selected from the group consisting of a network of cylindrical lenses, a network of spherical lenses and a parallax barrier, the process including the steps - creation of a period adapted to the optical selector (SO) and the system of reproduction used, - creation of a periodic image (IP) repetitively filled according to said period, of creating a dispersed image by applying a dispersion filter to the periodic image (IP) in which the geometric position of the pixels of the periodic image (IP) is modified according to the values of the pixels corresponding in the reference image (IR), connecting the scattered image (ID) thus created with the selector optical (SO). 2. Manufacturing process according to claim 1, characterized in that it further comprises a step of applying a blur on all or part of the reference image (IR), before the step of applying said filter of dispersion. 3. Manufacturing process according to claim 1 or 2, characterized in that than the step of creating the periodic image and / or the step of creating the image dispersed is carried out by means of at least one mask covering at least part of the periodic image and / or the scattered image and / or optical selector. 4. Manufacturing method according to one of claims 1 to 3, characterized in what the color mode of the period represents is a single layer color, bitmap or gray level, three layers red green blue, four layers cyan magenta yellow black, or two layers of colors whose clearest is a constant value on all of said period. 5. Manufacturing process according to one of claims 1 to 4, characterized in that the modification of the position of the pixels has an amplitude understood between 0.5 and twice the size of a period. 6. Manufacturing process according to one of claims 1 to 5, characterized in what the color mode of the reference image (IR) represents is a layer in grayscale, three layers red green blue. 7. Production method according to one of claims 1 to 6, characterized in the resolution of the reference image (IR) is less than or equal to the resolution of the periodic image (IP). 8. Manufacturing process according to one of claims 1 to 7, wherein the optical selector is a parallax barrier, and a second image scattered is created from the reference image by applying a second periodic image dispersion filter adapted to said parallax barrier, and the step of relating the two images scattered to create the iridescent image includes a reproduction said images scattered on either side or in a substrate transparent or translucent so the parallax barrier is consisting of one of the two scattered images in combination with the transparent or translucent substrate. 9. Dispersed image obtained from a reference image (IR) that represents either a grayscale layer or three red-green layers blue, four layers cyan magenta yellow black and / or all or part of which is applied a blur, and the scattered image being intended to be observed through an optical selector (SO), characterized in that the scattered image (ID) is shaped by modified position pixels by applying a dispersion filter in which the position Geometry of the pixels of a periodic image (IP) of determined period, is modified according to the values of the corresponding pixels in the image reference. 10. Iridescent image comprising a scattered image (ID) according to the claim 9, or obtained by the method according to one of claims 1 to 8 in which the reference image (IR) represents either a layer in greyscale, either three layers red green blue or four layers cyan black yellow magenta and / or all or part of which is applied a blur, the iridescent image being put in relation with an optical selector (SO) selected from the group consisting of a linear lens array, a network of spherical lenses, a parallax barrier. A secret image comprising a scattered image according to claim 9 or obtained by the method according to one of claims 1 to 8 wherein the reference image (IR) represents either a grayscale layer or three layers red green blue, four layers cyan magenta yellow black and / or on all or part of which is applied a blur, the secret image being intended for one or more given observers, characterized in that the period and / or the corresponding optical selector (SO) are known and / or held exclusively by the said one or more observers given so that you can recreate the corresponding iridescent image. 12. Anti-counterfeit security image including a scattered image according to claim 9 or obtained by the method according to one of the claims 1 to 8 in which the reference image (IR) represents either a layer in greyscale, either three layers red green blue or four layers cyan black yellow magenta and / or all or part of which is applied a blur, or an iridescent image according to claim 10 or obtained by the method according to one of claims 1 to 8 wherein the image of reference (IR) represents either a grayscale layer or three layers red green blue, four layers cyan magenta yellow black and / or on all or part of which is applied a blur. 13. Device characterized in that it comprises an iridescent image according to the claim 10, or obtained by the method according to one of the claims 1 to 8 in which the reference image (IR) represents either a layer in greyscale, either three layers red green blue or four layers cyan black yellow magenta and / or all or part of which is applied a blur, the device being selected from the group comprising a bank card or telephone, a window, a packaging, a decoration, a file of press, a greeting card, a garment or shoe mark, a ruler, a key ring, a bottle, a bottle, a plate, a glass, a vase, a shade, a communication element such as a commercial card, or a publishing product such as a poster, a postcard, a bookmark, a cover of a binder, a book, a notebook or a notebook, such a jewel a bracelet, a pendant, a brooch, the dial of a watch or even a clock, a tile, a glazing. 14. Computer program product that can be loaded into the memory a control unit such as a computer, comprising means for implementation of the method according to one of claims 1 to 8.