EP2189294A1 - Method for making a guilloched image, method for verifying the authenticity and/or printing said image on a medium and associated medium - Google Patents

Abstract

The method involves detecting a sensible zone (41) presenting a risk of falsification within an image. A guilloche id formed, where a pattern of the guilloche is adapted to the detected sensible zone. The guilloche is superpositioned to the image to obtain a guilloched image (31) ready to be printed or visualized on a medium. A set of lines (21a) of the guilloche are located concentric to another set of lines (21) of the guilloche, where the latter set of lines of the guilloche is utilized for reproducing a contour of the identified sensible zone. Independent claims are also included for the following: (1) a method for printing an guilloched image on a medium (2) a method for verifying authenticity of the guilloched image printed or visualized on the medium (3) a device for verifying the authenticity of the guilloched image printed or visualized on the medium.

Description

The invention relates to a method for producing a guilloche image obtained by superimposing a guilloche on an image, in order to be printed or displayed on a support thus secured. The invention also relates to a method of printing an image on a support comprising a prior step of superimposing a guilloche on the image. The invention particularly relates to any medium printed using this method or more generally any medium capable of allowing the display of a guilloche image and any title incorporating said support. The invention relates more particularly to titles allowing the identification of a user such as a passport, an identity card, a health card, an access card, a driver's license, a registration card of a vehicle and, without limitation, payment documents such as bank or postal checks, debit and / or credit cards, loyalty cards or any other document the need to reduce the risk of forgery.

Such documents or securities include at least one support in the form of various materials such as paper, plastic, PVC, PET, polycarbonate or more generally a material that can be printed using LASER printing techniques, jet of ink, offset etc.

To make complex the modification by a malicious person of texts, figures or images printed on a support, is used a set of means and / or techniques for securing said support. Among the best known, we can mention as examples, the use of protective films, holograms, fluorescent inks, fugitive, iridescent or thermosensitive, watermarks, embossing and guillochis.

• les motifs guillochés dits positifs présentant des lignes foncées sur fonds clairs ;
• les motifs guillochés négatifs présentant des lignes claires sur fonds de couleurs soutenues ;
• les motifs guillochés monocolores ou multicolores dont la couleur peut varier selon le contraste et la couleur du support sur lequel lesdits motifs guillochés sont appliqués...

A guilloche is usually a set of interwoven continuous lines forming geometric patterns. The printing of these guilloché motifs or other patterns of fine lines make it possible to prevent any attempt at recreating or reproducing images or text. There are several types of guilloche or fine line patterns. Among the most commonly used we can mention:

• the so-called positive guilloché patterns with dark lines on light backgrounds;
• negative guilloché patterns with clear lines on a solid background;
• monochrome or multicolored guilloche patterns, the color of which may vary according to the contrast and color of the medium on which the guilloche patterns are applied ...

To print a guilloche, known printing methods are used using a visible ink applied to a paper or plastic medium or to any other printable material.

Other methods of protection implement a guilloche printed with an ink invisible to the naked eye. This ink subsequently makes it possible to materialize an attempt to fraudulently modify the support by blistering the printed support or by roughly spreading the ink when the forger tries to apply it to transform a text or modify a photograph by adding a mustache by example to the person whose photograph is printed on the support.

Although the guilloche patterns used to date are prepared and elaborated in precise and complex ways making it difficult to reproduce, they are generally superimposed on an image comprising, a photo, a logo and / or an alphanumeric text, independently of said image. .

The document EP1889732A1 discloses, however, the possibility of varying the color of the fine lines during printing depending on the contrast or colors of a photograph or more generally of an image on which a guilloche is superimposed. This process makes it possible to optimize the visibility of the guilloche pattern. However, even if this technique is used, the lines of guilloche that we will also call guilloches, can sometimes be little or badly appropriate to prevent the modification of the image leaving the possibility to a malicious person to be able to modify the image without disturbing or visibly crush the guilloche. Indeed, the guilloche pattern being identical and reproducible, it becomes easy for a forger to scan the pattern and modify the image without visibly disturbing the guilloche. In such cases it is possible to add a scar, a mustache, glasses, to modify the outline of a face, a hair, an eye, of lips, to modify the content of a series of alphanumeric characters etc.

To overcome this type of inconvenience, solutions make it possible for example to integrate into a memory of an electronic circuit itself integrated in the support or title secure, the copy of the original image. Other extremely sophisticated techniques exist but all have the major disadvantage of generating significant costs during the manufacture or issuance of a security security but also during the validity check title by a security officer for example .

The invention aims to solve the disadvantages of the prior art by providing a simple, economical and extremely effective solution to prevent the forgery of secure media.

• une étape d'analyse pour détecter au sein de l'image une zone sensible présentant un risque de falsification;
• une étape pour élaborer un guillochis dont le motif est adapté à la zone sensible détectée;
• une étape de superposition dudit guillochis à l'image pour obtenir une image guillochée prête à être imprimée ou visualisée sur un support.

To this end, there is provided in particular a method for producing a guilloche image obtained by superposing a guilloche on an image, said method comprising:

• an analysis step for detecting within the image a sensitive zone presenting a risk of falsification;
• a step to develop a guilloche pattern whose pattern is adapted to the sensitive area detected;
• a superposition step of said guilloche in the image to obtain a guilloche image ready to be printed or visualized on a support.

The method may comprise as many steps to develop a guilloche as sensitive areas detected during the analysis of the image, said guilloche being superimposed on the image.

Preferably, the analysis step makes it possible to detect as a sensitive zone a shape, an alphanumeric character or a characteristic element of a portrait such as an eye, an ear, a lip, a implantation of hair, a scar, a mustache or any other characteristic element of a face.

The analysis step may for example consist in detecting a characteristic curve of a sensitive zone by the implementation of a Bayesian method, a wavelet theory or a Gabor filtering.

According to a first embodiment, the step of developing a guilloche adapted to a sensitive zone consists in drawing a line reproducing the contour of said zone. Optionally one or more lines may be drawn concentric to that reproducing the contour of the identified sensitive area.

According to a second embodiment, the step for producing a guilloche adapted to a sensitive zone may consist in drawing a line reproducing a pattern from a pattern gallery adapted to one or more typical sensitive areas.

The invention furthermore provides a method for printing a guilloché image on a support, comprising a step of superimposing a guilloche on an image and comprising a preliminary step for producing the guilloche according to a method according to the invention.

The latter also provides a printed medium or more generally a support adapted to allow the visualization of a guilloche image obtained by superposition of such guilloche to an image.

The invention further provides to adapt any title of identification or payment to include such a support.

• une étape d'analyse pour détecter au sein de l'image guillochée une zone sensible présentant un risque de falsification ;
• une étape pour vérifier un guillochis dont le motif est supposé être adapté à la zone sensible détectée ;
• une étape pour confirmer ou d'infirmer l'authenticité de l'image guillochée respectivement si ledit guillochis a ou n'a pas un motif adapté à la zone détectée.

The invention furthermore provides a method for verifying the authenticity of a guilloché image printed or displayed on a support, said guilloché image being obtained according to a method according to the invention, said verification method advantageously comprising:

• an analysis step for detecting in the guilloché image a sensitive zone presenting a risk of falsification;
• a step to check a guilloche whose pattern is supposed to be adapted to the sensed area detected;
• a step to confirm or invalidate the authenticity of the guilloche image respectively if said guilloche has or does not have a pattern adapted to the detected area.

Preferably, the step for verifying a guillochis whose pattern is supposed to be adapted to a detected sensitive zone may consist in ensuring that said pattern reproduces at least one line reproducing the contour of said zone. Alternatively, said step may consist in ensuring that said pattern reproduces a pattern from a pattern gallery adapted to one or more typical sensitive areas.

• des moyens pour analyser l'image guillochée et détecter une zone sensible présentant un risque de falsification ;
• des moyens pour vérifier le motif d'un guillochis au sein de ladite zone sensible, motif supposé être adapté à la zone sensible détectée ;
• des moyens pour confirmer ou infirmer l'authenticité de l'image guillochée respectivement si ledit guillochis a ou n'a pas un motif adapté à une zone sensible de l'image détectée.

The invention furthermore provides a device for verifying the authenticity of a guilloché image printed or displayed on a support, said guilloché image being obtained according to a method according to the invention, said device comprising:

• means for analyzing the guilloché image and detecting a sensitive zone presenting a risk of falsification;
• means for checking the pattern of a guilloche within said sensitive zone, a pattern assumed to be adapted to the detected sensitive zone;
• means for confirming or invalidating the authenticity of the guilloché image, respectively, if said guilloche has or does not have a pattern adapted to a sensitive zone of the detected image.

• la figure 1 présente un procédé selon l'art antérieur pour obtenir une image guillochée ;
• les figures 2 et 3 présentent respectivement des premier et second exemples selon l'invention d'élaboration d'un guillochis adapté pour prévenir la falsification d'une image imprimée sur un support.

Other features and advantages will emerge more clearly on reading the following description and on examining the figures that accompany it, among which:

• the figure 1 discloses a method according to the prior art to obtain a guilloche image;
• the figures 2 and 3 respectively present first and second examples according to the invention for producing a guilloche adapted to prevent falsification of an image printed on a support.

The figure 1 discloses a method according to the prior art for obtaining a guilloche image 3 from a guilloche 2 which is superimposed on an image 1. The guilloche used according to this example is a positive guilloche made from a set interlaced lines 2a and drawn according to a predetermined pattern. According to this known technique, the guilloche 2 is developed independently of the image 1 to which it is subsequently superimposed. It is then possible for a malevolent person with a certain skill and a good mastery of printing techniques to change certain areas of the face of the image 1. Thus the eye area or the eyebrows could be corrected or why not a mustache could be added. Although the figure 1 does not describe a guilloche image 3 presenting an alpha numeric text, it is possible to admit without effort that the technique according to the prior art would allow the fraudulent modification of said text to falsify an identification number or the surname of the wearer of a title on which a guilloche image conforming to image 3 would be printed.

On the contrary, the invention makes such a modification particularly difficult to achieve or at least makes the tampering attempt easily detectable.

Indeed, the method for producing a guilloche image according to the invention comprises a first step of analysis of the image to which will be superimposed a guillochis whose pattern is adapted to it. The figures 2 and 3 present two examples of implementation of the invention.

According to figure 2 an image 31 is obtained from an image with a male face. The photographed man has notable characteristics of wearing glasses whose glasses are oval and sports a mustache whose shape is similar to a relatively homogeneous rectangle.

Consider the mustache of the person concerned and consider how the invention makes it difficult and detectable an attempt to change the shape of this mustache.

According to the invention, a first step is to analyze the image so here a portrait. Using as a technique of analysis a Bayesian method or still another technique based on wavelet theory, it is possible to detect and delimit an area 41 of the face between the base of the nose and the upper lip. More precisely, the use of these techniques makes it possible to detect the presence of a mustache and to determine its outline. It is also possible to exploit Gabor filtering or any other mathematical technique that applied to image analysis, would allow such detection.

The method according to the invention further comprises a step for developing a guilloche pattern whose pattern is dedicated and adapted to the area 41 corresponding to the mustache. According to the example presented in connection with figure 2 , a step allows to develop a guillochis adapted to the zone 41. On the figure 2 such a guillochis consists of a line 21 emphasizing the outline of the mustache. Alternatively other lines 21a can be drawn in the form of for example a negative guilloche, concentric lines to the line 21 to properly materialize the area, texture and shape of the mustache. According to the invention, if a malicious person tries to modify the outline of the mustache, it would no longer comply with the guilloche 21 and 21a. It would then be easy, as explained below, to detect falsification.

During the image analysis step, according to a similar procedure, the method according to the invention could detect the presence of the pair of glasses and determine the shape of glasses. In the same way a guilloche could then be developed to materialize and characterize the presence and the shape of the glasses of said pair of glasses.

The guillochis composed of line 21, or even lines 21a, is subsequently superimposed on the portrait to obtain the guilloche image 31.

As suggested by figure 2 , the invention also superimposes a guilloche having a predetermined pattern to cover, as in the prior art, the rest or the whole of the image. Such a guilloche can be elaborated from a particular pattern or from an applicable pattern gallery. The lines of this guilloche covering particularly insensitive areas may alternatively follow random trajectories.

In the same way, the guillochis covering the zone 41 can be elaborated not by reproducing the contour of the detected mustache but from a pattern coming from a pattern gallery adapted to one or more typical sensitive zones, such as the eye, ear, mustache or basic geometric shapes as part of the protection of a logo or symbols or characters for an alphanumeric text.

The figure 3 illustrates how the invention makes delicate not the modification of a line of a face but the addition of a scar for example or a mustache.

So the figure 3 illustrates a guilloché image 32 obtained from a portrait of a man wearing a pair of glasses but, unlike the image 31, this man does not wear a mustache. The invention prevents the addition of a mustache by developing a guilloche whose pattern is adapted to materialize the absence of this distinctive sign. Thus, the method for obtaining the image 32 consists in analyzing the portrait and detecting a zone 42 between the base of the nose and the upper lip, sensitive zone because presenting a risk of high falsification. The method according to the invention detects said zone and confirms the absence of mustache. The method according to the invention also comprises a step for producing a guilloche whose pattern is characteristic of the absence of mustache. For this purpose a line 22 is produced from, for example, a pattern from a pattern gallery adapted to one or more typical sensitive areas. In a variant, this line 22 follows within the zone 42 a random plot. According to another variant, the line 22 is associated with one or more additional lines of identical or different colors to constitute the guilloche.

In the same way as for the figure 2 , the guilloche image 32 is obtained by superposition of said guillochis to the portrait. The superposition step can be completed by the superimposition of one or more guillochis whose pattern is adapted to other sensitive areas detected or even a guilloche covering all or part of the door.

According to a preferred variant, the guilloche covering the non-sensitive areas of an image comprises one or more lines bypassing a sensitive zone. According to a second variant, said guillochis, which we will call bottom guillochis, covers the entire image without distinction as guillochis 2 according to the prior art.

According to a third variant, the step of superposition of a guillochis whose pattern is adapted to a sensitive zone replaces the lines of the ground guilloche pattern. According to a fourth variant, the lines of the different guilloche cross and overlap.

The invention also relates to a method of printing a guilloche image 31 or 32 on a support, whatever the nature of said support. It suffices for this purpose that the printing method comprises a step for analyzing the image and detecting one or more sensitive zones and a step for producing one or more guillochis dedicated to said detected sensitive zones. These steps to analyze the image and develop a guilloche are preferably implemented before the superimposition of said guilloche in the image.

The guillochis whose pattern is adapted to a sensitive area is printed preferentially with an ink visible to the naked eye. Alternatively, all or part of the guilloche is printed using an ink invisible to the naked eye. Invisible guilloches are used to reveal an attempt to change the content of the image resulting in blistering of the ink or medium or coarse diffusion of the ink applied by the malicious person.

The invention further relates to any suitable or printed support for viewing a guilloche image according to the invention. The invention preferably relates to a printed medium but also a medium having a screen for displaying such a guilloche image. The invention more generally relates to any electronic device capable of developing, distributing or displaying a guilloche image of which all or part of the guilloche has been adapted to an area or several sensitive areas.

The invention also relates to a method for verifying the authenticity of a guilloche image according to the invention, printed or displayed on a support. For this, consider a guilloche image previously obtained according to a method for superimposing on an image a guilloche pattern whose pattern is adapted to at least one sensitive zone as previously studied.

A verification method according to the invention comprises an analysis step for detecting a sensitive zone within the guilloche image. According to a procedure similar to that studied to develop the guilloche image, the analysis step consists in implementing an analysis technique such as a Bayesian method or a technique based on wavelet theory to detect and delimit a sensitive area likely to be potentially the target of forgery. As a variant, other mathematical techniques applied to image analysis are exploited such as a Gabor filtering to identify a distinctive sign or portion of a logo or an alphanumeric character. According to the invention the verification method further comprises a step for verifying a guilloche whose pattern is supposed to be adapted to a detected sensitive zone. In order to conform to the invention and to secure an image, the pattern of a guilloche pattern superimposed on a sensitive zone of the image is adapted to reproduce as an example the outline of a distinctive sign, such as a mustache, or to be representative of the texture, the shape of said sign, etc. The invention therefore consists in providing a verification method comprising a step for confirming or invalidating the authenticity of the image respectively if said guilloche has or does not have a pattern adapted to the zone detected in accordance with the invention. Thus the verification process validates the motive of the guilloche concerned for an area. According to a first embodiment, the verification process performs an extraction of the guilloche and compares it with a reference guillochis itself developed following the analysis step. As a variant, the verification method compares the pattern of an extracted guilloche with motifs from a pattern gallery adapted to one or more typical sensitive zones.

Thanks to the implementation of the verification method according to the invention, it is possible in particular for a security agent to see an attempt to fraudulently modify a guilloche image on a support.

Such a method may be implemented in an electronic device adapted to include, in particular, means for analyzing an image displayed or printed on a support, means for verifying a guillochis whose pattern is supposed to be adapted to the detected sensitive zone and means for to confirm or invalidate the authenticity of the image respectively if said guilloche has or does not have a pattern adapted to a sensitive area of the detected image.

Claims (15)

Process for producing a guilloche image (3, 31, 32) obtained by superposing a guilloche (2, 21, 21a, 22) on an image (1), characterized in that it comprises: an analysis step for detecting, within the image (1), a sensitive zone (41, 42) presenting a risk of falsification; a step for producing a guillochis (21, 21a, 22) whose pattern is adapted to the detected sensitive zone (41, 42); a superposition step of said guillochis in the image to obtain a guilloche image (31, 32) ready to be printed or visualized on a support. Process according to Claim 1, characterized in that it comprises as many steps for producing a guillochis (21, 21a, 22) as detected sensitive zones (41, 42) during the analysis of the image, said guillochis being superimposed on the image. Method according to claim 1 or 2,
characterized in that the analyzing step makes it possible to detect, as sensitive zone, a shape, an alphanumeric character or a characteristic element of a portrait such as an eye, an ear, a lip, a hair implantation, a scar, a mustache or any other characteristic element of a face. Process according to any one of the preceding claims, characterized in that the analysis step consists in detecting preferentially a characteristic curve of a sensitive zone by the implementation of a Bayesian method, a wavelet theory or a Gabor filtering. Process according to any one of the preceding claims, characterized in that the step of producing a guilloche (21, 21a, 22) adapted to a sensitive zone consists of drawing a line (21) reproducing the contour of said zone. Method according to the preceding claim, characterized in that one or more lines are drawn concentrically (21a) to that (21) reproducing the contour of the identified sensitive zone. Process according to any one of Claims 1 to 4, characterized in that the step for producing a guilloche (21, 21a, 22) adapted to a sensitive zone (41, 42) consists in drawing a line reproducing a pattern derived from a pattern gallery adapted to one or more typical sensitive areas. A method for printing a guilloché image on a support, comprising a step of superimposing a guilloche on an image, characterized in that it comprises a preliminary step for producing the guilloche according to a method according to the preceding claims. Printed support comprising a guilloche image obtained by superposing a guilloche on an image, characterized in that the guillochis has been produced according to the process according to claims 1 to 7. Support for displaying a guilloche image obtained by superposing a guilloche on an image, characterized in that the guillochis has been produced according to the process according to claims 1 to 7. Title of identification or payment,
characterized in that it comprises a support according to claim 9 or 10. A method of verifying the authenticity of a guilloché image (3, 31, 32) printed or displayed on a support, said guilloché image being obtained according to a method according to any one of claims 1 to 7, said verification method characterized in that it comprises: - an analysis step for detecting in the guilloche image a sensitive zone (41, 42) presenting a risk of falsification; a step for checking a guilloche (21, 21a, 22) whose pattern is supposed to be adapted to the detected sensitive zone; a step to confirm or invalidate the authenticity of the guilloché image (3, 31, 32) respectively if said guilloche (21, 21a, 22) has or does not have a pattern adapted to the detected area (41, 42). Verification method according to the preceding claim, characterized in that the step of verifying a guilloche whose pattern is supposed to be adapted to a detected sensitive zone consists in ensuring that said pattern reproduces at least one line (21) reproducing the outline of said zone (41). Verification method according to claim 13, characterized in that the step of verifying a guillochis whose pattern is supposed to be adapted to a sensed sensitive zone consists in ensuring that said pattern reproduces a pattern from a suitable motif gallery to one or more typical hotspots. Device for verifying the authenticity of a guilloché image (3, 31, 32) printed or displayed on a support, said guilloché image being obtained according to a method according to any one of Claims 1 to 7, characterized in that it includes: means for analyzing the guilloché image and detecting a sensitive zone (41, 42) presenting a risk of falsification; means for checking the pattern of a guillochis (21, 21a, 22) within said sensitive zone, a pattern supposed to be adapted to the detected sensitive zone; means for confirming or invalidating the authenticity of the guilloché image (3, 31, 32) respectively if said guilloche (21, 21a, 22) has or does not have a pattern adapted to a sensitive zone (41, 42 ) of the detected image.

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