WO2016062900A1

WO2016062900A1 - Copy-sensitive graphic visual code with two information levels, methods of generating and reading a visual code of this type

Info

Publication number: WO2016062900A1
Application number: PCT/EP2015/075403
Authority: WO
Inventors: Iuliia TKACHENKO; Christophe DESTRUEL; Jean-Marc Gaudin; William Puech; Olivier STRAUSS
Original assignee: Authentication Industries; Centre National De La Recherche Scientifique; Universite De Montpellier
Priority date: 2014-10-20
Filing date: 2015-11-02
Publication date: 2016-04-28
Also published as: FR3027430B1; FR3027430A1

Abstract

The invention relates to a graphic visual code (200) composed of a plurality of graphic patterns, known as primary patterns, of which the spatial arrangement with respect to one another represents predetermined information, known as primary information, which can be read by an optical reader means performing a predetermined reading application, known as the primary reading application. The invention is characterized in that at least one of the primary patterns (202), known as the enriched pattern, comprises at least one graphic pattern, known as the secondary pattern, representing an item of information, known as the secondary information, and readable by an optical reader means performing a reading application, known as the secondary reading application. The invention also relates to methods and devices for generating and reading a graphic visual code of this type.

Description

"Graphic visual code with two levels of information and sensitive to the copy, methods of generating and reading such a visual code"

The invention relates to a graphical visual code, such as a bar code in one or two dimensions, a QR code, etc. at two levels of information and copy-sensitive. It also relates to methods and devices for generating and reading such a graphical visual code.

The field of the invention is the field of graphical visual codes (barcodes) such as EAN barcodes, Unit Product Codes, Datamatrix, QR Code, etc.

State of the art

Nowadays, one- or multi-dimensional graphic visual codes are used in many applications, reaching an increasingly large audience. The most commonly used visual codes are EAN barcodes, which are one-dimensional codes, or QR codes that are two-dimensional visual codes. Most of these codes are readable by many devices including a visual code scanning means and a software application for decoding the digitized visual code. For example, smartphones with a camera and a software application can read the visual codes.

Visual codes have limited capacity for the information they can represent. At the same time, there is today a growing need for an increase in the ability of visual codes to store in these codes even more information.

Efforts have been made and various work in the field has resulted in codes with greater storage capacity, such as HCCB (High Capacity Color Barcode) or HCC2D (for High Capacity Colored 2). -Dimensionnal Code "in English).

However, the HCCB code has major drawbacks including a fragility at the detection and a fragility of location. It imposes well on a specific reading application. The HCC2D code, meanwhile, requires a specific reading application that makes it unreadable by existing applications.

In addition, all these codes are easily copiable which makes them unusable in authentication applications.

The invention aims to overcome the aforementioned drawbacks.

Another object of the invention is to propose a visual code whose storage capacities are increased and which can be read by existing applications.

Another object of the invention is to propose a visual code allowing a greater flexibility of choice in the coding of the information.

Finally, another object of the invention is to provide a visual code that can be used in authentication applications.

Presentation of the invention

The invention makes it possible to achieve at least one of the aforementioned objects by a graphical visual code composed of a plurality of graphic patterns, called primary patterns, whose spatial arrangement with each other represents a predetermined information, called information primary, readable by optical reading means executing a predetermined reading application, said primary, characterized in that at least one of said primary patterns, said enriched pattern, comprises at least one graphic pattern, said secondary pattern, representing a so-called information secondary, and readable by an optical reading means executing a reading application, said secondary.

In other words, the graphical visual code according to the invention comprises at least one enriched primary pattern, obtained by superposition of a primary pattern and at least one secondary pattern, which replaces said primary pattern.

The method according to the invention therefore proposes a graphical visual code comprising a first reading level, comprising a first piece of information that can be read by any application designed for this code and a second reading level, comprising second information that can be read by an application different from the first application.

In other words, the method according to the invention proposes to add to any existing graphical visual code, such as the QR codes or the 1D barcodes, a second level of information by adding in the basic patterns used to generating these codes, reasons bearing secondary information. This secondary information may be information that complements the primary information represented by the existing code or information for verifying the primary information, or any other desired information.

Thus, the second level of information, constituted by the secondary reasons, makes it possible to increase the capacity of the existing graphic visual codes, while allowing the primary information represented by the existing code to be read by any existing application.

In addition, the user has, with the code according to the invention, two levels of information allowing him flexibility in the choice of the information he wishes to communicate, and in the order in which he wishes to communicate this information. information.

Finally, the second level of information can be used to authenticate the information contained in the first level of information, which makes it possible to use the graphical visual code according to the invention in applications with a need for authentication.

In this application:

- Primary information means the information represented by the graphic patterns constituting / forming the graphical visual code; and

- Secondary information means the information represented by the graphic patterns embedded in one or more patterns constituting / forming the graphical visual code.

The appellations "primary" and "secondary" are used in the present application to distinguish between two objects, without constituting any dependence or hierarchical level between these two objects. Advantageously, the primary and secondary pattern constituting an enriched pattern can be chosen so that the value of a predetermined parameter calculated as a function of said primary pattern and of said enriched pattern satisfies a predetermined threshold value.

This feature makes it possible to limit the modifications made to the existing graphical visual code when registering secondary motifs in the primary patterns. Thus, it is possible to adjust these modifications to ensure that the graphical visual code can be used in any existing application, and be read by any existing reading means without having to modify these existing applications or these means. existing reading.

Preferably, the primary and secondary patterns constituting an enriched pattern may be chosen such that a relative density of said enriched pattern with respect to said primary pattern is greater than or equal to a threshold value of 0.5.

The relative density and correlation parameters are easily measurable parameters from a digitized image of the code with predetermined measurement functions, which may each be pre-filled in generation applications of the primary, secondary and enriched patterns, or in the method of generating a graphical visual code according to the invention.

The threshold values may be adjustable by the user according to the accuracies desired by the user, for example according to the application in which the graphical visual code according to the invention is used.

In the present application, by graphic visual code production process is meant a representation of the graphic visual code either by printing the graphic visual code on a physical medium, or by displaying the visual code on a display screen. This production process is part of a normal use of graphical visual code, even though the graphical visual code may never be printed or represented. The version of the graphical visual code obtained following a production process is called the "produced version".

This production process is performed with precision pl. In the present application, by reproduction process is meant a reproduction of the graphical visual code previously produced, that is to say a reproduction of the graphical visual code previously printed on a physical medium or a reproduction of the graphical visual code previously displayed on a display screen.

The version of the graphical visual code obtained following a reproduction process is called "reproduced version".

This reproduction process comprises:

a scanning step, with a precision p2, either from a physical medium or from a display screen; and a representation step, by printing on a physical medium or by displaying on a display screen, with a precision p3.

The reproduction process can be predefined, for example, by specifying values or precision limits for the scanning operation and the printing operation.

For example, the reproduction process can be defined by:

a scanning operation having a scanning accuracy of less than or equal to 2400dpi, and

a printing operation having a print accuracy of less than or equal to 2400dpi.

Of course, these values are in no way limiting and may be modified to adjust the copy sensitivity of the graphical visual code according to the invention, to a specific application, such as a consumer application or a specific application having a precision of reproduction that can be obtained in a consumer application.

Preferably, when the graphical visual code comprises several different secondary motifs, at least one, preferentially each secondary pattern can be chosen from a database, called secondary, and can have a texture, a density and / or a shape such that the ratio between:

a correlation value between said original version of the enriched primary pattern with said secondary pattern in said secondary base and another secondary pattern in said produced version of said code, and

a correlation value between the original version of the enriched primary pattern with said secondary pattern and said secondary pattern in a produced version of said code;

has a ratio less than or equal to a predetermined threshold.

This predetermined threshold value may be adjustable by the user according to the accuracies desired by the user, for example according to the application in which the graphical visual code according to the invention is used.

According to a preferred example, the predetermined threshold value may be equal to 0.95.

In addition, according to a preferred version, when the graphical visual code comprises several different secondary patterns, at least one, preferably each, secondary pattern may be chosen from a database, called secondary, and may have a texture, a density and / or or a form such that the ratio between:

a correlation value between the primary pattern enriched with said secondary pattern in a produced version of said code and an original version of at least one, preferably each, secondary pattern in said base, and

a correlation value between the primary pattern enriched with said secondary pattern in said produced version of said code and the original version of said secondary pattern in said base; has a ratio less than or equal to a predetermined threshold.

This predetermined threshold value may be adjustable by the user according to the accuracies desired by the user, for example according to of the application in which the graphical visual code according to the invention is used.

In a preferred version of the graphical visual code according to the invention, at least one, preferably each, secondary pattern may be chosen in a so-called secondary base, and may preferably have a texture, density and / or shape such as when the code is reproduced by a predetermined reproduction process, in particular a reproduction process in which:

the digitization (or acquisition) accuracy p2 <2pl, and preferably p2 <2,5pl; and or

- the representation precision p3 <pl;

said secondary pattern on the reproduced version of said code thus obtained, can no longer be read by the secondary application.

Thus, the graphical visual code according to the invention is then copy-sensitive and allows the user to detect an original visual code, ie a visual code produced, a copy or a reproduction of this code obtained by scanning and printing.

More precisely, in this preferred version, at least one, preferably each, secondary pattern can be chosen so that the ratio between:

a correlation value between the primary pattern enriched with said secondary pattern in the reproduced version of said code and the original version of said secondary pattern in the secondary base, and

a correlation value between the primary pattern enriched with said secondary pattern in the produced version of said code and the original version of said secondary pattern in the secondary base; has a ratio less than or equal to a predetermined threshold.

As mentioned above, the correlation parameter is an easily measurable parameter from a digitized image of the graphical visual code with a predetermined function, which can be pre-determined. provided in an application for generating the secondary and / or enriched patterns, or in the method of generating a graphical visual code according to the invention.

The predetermined threshold value may be adjustable by the user according to the accuracies desired by the user, for example according to the application in which the graphical visual code according to the invention is used.

According to a preferred example, the predetermined threshold value for the correlation is equal to 0.75.

According to the invention, the predetermined correlation function is, preferentially but not exclusively, the Pearson correlation.

According to the invention, the predetermined function of calculation of relative density can be any known density calculation function.

Advantageously, the graphical visual code according to the invention may comprise a plurality of enriched primary patterns, each comprising one or more secondary patterns, the secondary information being determined as a function of all of said secondary patterns, and possibly according to their arrangement. in said code.

Such a code according to the invention has a greater capacity for storing information.

More particularly, it is possible to determine, prior to the generation of the visual code according to the invention, a secondary pattern alphabet that can be used for each primary pattern or for each type / version of existing graphical graphic code. During the generation of the graphical visual code according to the invention, it is then possible to select in this alphabet the secondary pattern (s) coding the secondary information.

In a particularly preferred version of the graphical visual code according to the invention, at least one, preferably each, enriched primary pattern is binary. In other words, each primary pattern is of a first color and each secondary pattern is of a second color having a sufficiently high contrast relative to the first color to be read by the secondary reading apparatus.

According to a preferred embodiment, the graphical visual code according to the invention is in black and white, namely that each primary pattern is in black and each secondary pattern is white.

In this case, for each primary pattern, each secondary pattern may advantageously be chosen so that each enriched primary pattern has a percentage of black pixel constant and equal to a predetermined value.

According to a preferred example, the constant percentage is greater than or equal to 50%.

For example, the constant percentage may be, without limitation, less than 90%, or even 95%.

Of course, each primary pattern may be the same or different from another primary pattern. When they are different from each other, the primary patterns may constitute an alphabet, or a base, called primary.

Likewise, each secondary pattern may be the same or different from another secondary pattern. When they are different from each other, the secondary patterns may constitute an alphabet, or a so-called secondary base.

In a preferred manner, the primary patterns of the graphical visual code according to the invention form a bar code such as a QR code or a 1D bar code.

According to another aspect of the same invention, there is provided a method for generating a graphical visual code according to the invention, characterized in that it comprises the following steps: generating, by a so-called primary generation application, a visual code, said initial, by spatial arrangement of a plurality of primary patterns according to the primary information, and

- Registration, by a so-called secondary generation application, of at least one secondary pattern on at least one of said primary patterns of said initial visual code, depending on the secondary information and said initial visual code;

and optionally, representation of the visual code thus obtained by printing said visual code on a material medium or a display on a display screen.

In other words, during the registration step, at least one primary pattern of the graphical visual code generated during the generation step is replaced by an enriched primary pattern obtained by superimposing at least one secondary pattern with said pattern. primary.

Of course, the primary generation application may be an application independent of the secondary generation application.

Alternatively, the two generation applications can be integrated into a single application performing the generation steps / functions at the same time or in turn.

The method according to the invention may further comprise a step of generating the secondary information as a function of the primary information, for example by means of a predetermined code algorithm.

In this case, the secondary information is dependent on the primary information which brings greater security against the falsification of the visual code.

The registration step may include a step of selecting, in a database, at least one secondary pattern that will be registered in at least one primary pattern based on the secondary information and the secondary generation application. , and possibly the primary pattern for example to respect a predetermined value of percentage of black pixels in the enriched pattern and / or correlation, or at least one of the criteria defined above in relation to the original version of a pattern secondary, the secondary reason in produced version and / or a reproduced version of graphic visual code etc.

The generation method according to the invention may comprise, prior to the registration step and for at least one primary pattern, a step of generating and storing in a so-called secondary base or alphabet at least one secondary pattern , according to:

a relative density value of an enriched pattern obtainable with said secondary pattern and said primary pattern with respect to said primary pattern, and at least one threshold value for said relative density; and or

- a relationship between:

^■ a correlation value between the primary pattern enriched with said original version of said secondary pattern and another secondary pattern in a production version of said graphic display code, and

^■ a correlation value between the primary pattern enriched with said secondary pattern in an original version in a database of said secondary pattern and said secondary pattern in a production version of said graphic display code;

and at least one threshold value for said ratio, as defined above; and or

- a relationship between:

^■ a correlation value between the primary pattern enriched with said secondary pattern in a version of said generated code and an original version of at least one, preferably each, secondary pattern in said base, and

^■ a correlation value between the primary pattern enriched with said secondary pattern in said generated version of said code and the original version of said secondary pattern in said base; and at least one threshold value for said ratio, as defined above; and or

- a relationship between:

^■ a correlation value between the primary pattern enriched with said original pattern of said secondary and said secondary pattern in a reproduced version of said graphic display code, and

^■ a correlation value between the primary pattern enriched with said secondary pattern in an original version in a database and said secondary pattern in a production version of said graphic display code;

and at least one threshold value for said ratio, as defined above; The threshold values used may, in a nonlimiting manner, be those given above.

For example, the reproduction process may meet the scan and print accuracy values given above.

According to yet another aspect of the invention, there is provided a device for generating a graphical visual code according to the invention comprising the means arranged to implement all the steps of the generation method according to the invention.

More particularly, the generation device can comprise:

a so-called primary generation means for a so-called initial visual code, by spatial arrangement of a plurality of primary patterns according to the primary information, and

a so-called secondary generation means of at least one secondary pattern to be written on at least one of said primary patterns of said initial visual code, as a function of the secondary information and of said initial visual code; and optionally, a means of representing the visual code thus obtained by printing said visual code on a hardware medium or a computer display.

Of course, the primary generation means and the secondary generation means can be integrated in a single means which comprises:

a so-called primary generation application for generating the initial code, and a so-called secondary generation application for generating and registering the secondary patterns; or

- a single application performing both functions at the same time or in turn.

The representation means may comprise a printing medium on a physical medium, such as an ink jet printer or a laser printer.

The representation means may, alternatively or in addition, comprise a graphic generation means, such as a graphics card, and a display screen on which the graphical graphic code according to the invention is displayed.

According to yet another aspect of the invention, there is provided a method of reading a graphical visual code according to the invention, characterized in that it comprises the following steps:

possibly, digitizing the visual code by capturing an image of said visual code,

reading by the primary reading application of the primary information from the visual code,

reading by the secondary reading application of the secondary information from the visual code, said reading comprising the following operations:

^■ identification of each primary pattern in the graphical visual code,

^■ for each primary pattern, determining a correlation value with each primary pattern enriched with the pattern secondary of the secondary pattern base, said determination identifying the secondary pattern inscribed in said primary pattern when said primary pattern comprises a secondary pattern,

Determination, by the secondary readout application of the secondary information, as a function of the secondary reasons identified and possibly of their spatial arrangement.

Of course, the primary reading application may be an application independent of the secondary reading application. Alternatively, the two reading applications can be integrated in a single application performing the two steps / reading functions at the same time or in turn.

The scanning means may be a scanner or a camera, for example the camera of a smartphone or a device dedicated to reading the code formed by the primary patterns.

The method according to the invention may further comprise a step of detecting a reproduction or non-reproduction of the graphic visual code as a function of at least one correlation value and of at least one predetermined threshold, in particular as defined above. .

According to yet another aspect of the invention, there is provided a device for reading a graphical visual code according to the invention comprising the means arranged to implement all the steps of the reading method according to the invention.

In particular, the reading device can comprise:

possibly a means for digitizing the visual code by capturing an image of said visual code,

a means of reading, called primary, of the primary information from the graphical visual code,

a secondary reading means for secondary information from the graphical visual code, said reading comprising the following operations: ^■ identification of each primary pattern in the graphical visual code,

^■ for each primary pattern, determining a correlation value with each primary pattern enriched with the secondary ground of the base of second units, said determining identifying the secondary pattern registered in said primary pattern when said primary pattern comprises a secondary pattern,

^■ determination of the secondary information, according to the secondary reasons identified and possibly their spatial arrangement.

The primary reading means comprises the primary reading application and the secondary reading means comprises the secondary reading application.

Of course, the primary reading means and the secondary reading means can be integrated into a single means which comprises:

the primary reading application for reading the primary information, and the secondary reading application for reading the secondary information; or

- a single application performing both playback functions at the same time or in turn.

More particularly, the device for reading the graphical visual code according to the invention may be a Smartphone, or a dedicated reading device, comprising a scanning means and the reading application (s).

The graphical visual code according to the invention can be used in the following applications:

- Ticketing,

- product labeling, - monitoring and protection of sensitive documents,

- etc.

Other advantages and characteristics will appear on examining the detailed description of the non-limitative examples, and the appended drawings in which:

- FIGURE 1 is a schematic representation of a non-limiting example of a graphical visual code according to the state of the art;

FIG. 2 is a schematic representation of a non-limiting example of a graphic visual code according to the invention;

FIG. 3 is a schematic representation of an example of enriched patterns used in the graphical visual code according to the invention of FIG. 2;

FIG. 4 is a diagrammatic representation of a nonlimiting example of a method for generating a graphic visual code according to the invention;

FIG. 5 is a diagrammatic representation of a nonlimiting example of a device for generating a graphic visual code according to the invention;

FIG. 6 is a diagrammatic representation of a nonlimiting example of a method for reading a graphic visual code according to the invention; and

- FIGURE 7 is a schematic representation of a non-limiting example of a device for reading a graphical visual code according to the invention.

It is understood that the embodiments which will be described in the following are in no way limiting. It will be possible to imagine variants of the invention comprising only a selection of characteristics described below, isolated from the other characteristics described, if this selection of characteristics is sufficient to confer a technical advantage or to differentiate the invention from the state of the prior art. This selection comprises at least one feature preferably functional without structural details, or with only a part of the structural details if this part alone is sufficient to confer a technical advantage or to differentiate the invention from the state of the prior art.

In particular, all the variants and all the embodiments described are combinable with each other if nothing stands in the way of this combination at the technical level.

In the figures, the elements common to several figures retain the same reference.

FIG. 1 is a schematic representation of an example of a graphical visual code according to the state of the art.

The visual graphic code 100 of the state of the art shown in FIG. 1 is a QR Code. Such visual graphic code is well known to those skilled in the art. We will not describe here the process of generating a QR Code and the method of reading a QR Code.

The QR Code shown in FIG. 1 is obtained by a spatial arrangement of a multitude of a single primary pattern in the form of a square of black color, such as, for example, the square referenced 102 in FIG. 1.

The QR code 100 further comprises three patterns 104, at three of these corners, for detecting and locating the QR code 100 and the orientation of the QR code 100.

Of course, the example given in FIGURE 1 is not limiting. There are graphical visual codes similar to the QR code and formed by graphic primary patterns that are not all identical as in the case of the QR Code. There are, for example, graphic visual codes formed by graphic primary patterns of the same shape but of different colors: either in grayscale or according to a predetermined color palette.

There are also graphical visual codes in the form of a 1D barcode, etc. In all these codes, the arrangement of the same or different primary graphic patterns represents information, which is called in the present application primary information.

The invention makes it possible to use all the existing visual codes with the existing reading applications for these codes. The invention makes it possible to add to each of these codes, in addition to the level of reading formed by the primary graphic patterns, a second level of reading which is formed by secondary graphic patterns inserted / inlaid / superimposed with at least a part of primary reasons. This second level of reading, that is to say the set of secondary graphic patterns, is readable by a reading application, called secondary, which is different from the so-called primary reading application of the primary graphic patterns of the existing codes.

FIGURE 2 is a schematic representation of a non-limiting example of a graphical visual code according to the invention having two different reading levels.

The code 200 shown in FIG. 2 is obtained by adding to QR Code 100 of FIGURE 1 a second reading level.

This second reading level is obtained by superimposing on the primary patterns 102 of the code 100 of FIG. 1, secondary graphic patterns that are readable by a secondary read application different from the primary readout application of the primary patterns 102, the superposition of a primary pattern with a secondary pattern providing an enriched primary pattern 202.

In the example shown in FIG. 2, each secondary reading pattern consists of a set of points / pixels of white color. With the exception of the mandatory elements (imposed by the standard) 104, the code 200 represented in FIG. 2 is entirely made up of graphic patterns, called enriched patterns, obtained by superimposing a secondary pattern on a primary pattern. FIG. 3 is a schematic representation of an example of rich graphic patterns used in the graphical visual code according to the invention of FIG. 2.

More particularly, the graphic visual code 200 shown in FIG. 2 consists entirely of 2 enriched patterns 302 and 304 different from each other. Each of the enriched patterns 302-304 is obtained by superimposing, on the single primary pattern 102 of FIGURE 1 which is in the form of a black square, two different secondary patterns 308 and 310 each comprising one or more white squares. identical smaller size compared to the primary pattern 102.

More specifically, the enriched pattern 302 is obtained by superimposing on the primary pattern 102 the secondary graphic pattern 308 which is composed of a white square 314 positioned at the center of the secondary pattern 308.

The enriched pattern 304 is obtained by superimposing on the primary pattern 102 the secondary graphic pattern 310 which is composed of four white squares 314 each positioned at the center of each of the sides and at the edge of the secondary pattern 310.

Each of the primary and secondary patterns are chosen so that the enriched primary pattern, in particular each of the patterns 302-304, obtained by superimposing a primary pattern, in particular the pattern 102, with a secondary pattern, in particular each of the patterns. 308-310, has a relative density with respect to the primary unit greater than or equal to 0.84.

In addition, each of the secondary patterns, in particular each of the patterns 308-310, is selected with respect to threshold correlation ratio values calculated based on each original secondary pattern, and each secondary pattern in a produced version of the visual code. graphic and each secondary pattern in a reproduced version of the graphical visual code.

In particular, each secondary pattern is chosen so that:

- the relationship between :

o a correlation value between the original version of the primary pattern enriched with this pattern, and another pattern secondary in a produced version of the graphical visual code; and

o a correlation value between the original version of this enriched primary pattern, and this pattern in a produced version of the graphical visual code;

is less than or equal to 0.95;

- the relationship between :

o a correlation value between the original version of this pattern, and this pattern in a reproduced version of the graphical visual code; and

o a correlation value between the original version of this pattern, and this pattern in a produced version of the graphical visual code;

is less than or equal to 0.75; and

- the relationship between :

o a correlation value between the primary pattern enriched with said secondary pattern in said produced version of said code and the original version of said secondary pattern in said base;

is less than or equal to 0.95.

Secondary graphic patterns satisfying these density criteria, and correlation ratios can be previously selected by conducting a test battery.

To meet these criteria, and in particular the density and correlation ratio criteria, one or more secondary patterns can be tested for each primary pattern. Secondary units satisfying these criteria may be stored in a secondary pattern basis, possibly in combination with the primary pattern for which they meet the stated criteria. A coding / decoding alphabet can then be determined based on:

- secondary reasons satisfying the criteria defined above, - their combination with each other,

- their relative arrangements between them,

- their arrangements in the primary pattern, and / or

- their arrangements in the graphical visual code.

FIGURE 4 is a schematic representation of a non-limiting example of a method for generating a graphical visual code according to the invention.

The method 400 shown in FIG. 4 comprises an initial step 402 determining, for one or more primary units of a graphical visual code, one or more secondary units complying with the density and correlation criteria described above. The secondary reasons can for example be determined by tests carried out under real conditions. Depending on the secondary reasons determined, a graphics coding / decoding algorithm is also determined in this step 402 to encode a given information from the secondary patterns and primary patterns. This algorithm specifies, for example, for a given information, the spatial arrangement and the combination of secondary motifs in a graphical visual code formed by the primary patterns to represent the given information.

In a step 404, a known graphical graphic code, formed solely by primary patterns, is generated based on a primary information and a known primary generation application. During this step 404 the graphical visual code is not yet represented visually on a physical or computer medium.

Then, during a step 406, the secondary patterns to be inscribed in the primary patterns of the graphical visual code generated during step 404 are written on one or more primary patterns of this graphical visual code according to a spatial arrangement and / or a combination determined by a generation application, said secondary, using the algorithm determined in step 402.

In other words, during this step 406, at least one primary pattern generated in step 404 is replaced by an enriched primary pattern obtained by superimposing said primary pattern with at least one secondary pattern.

At the end of this step 406, a graphic visual code comprising at least one enriched primary pattern is obtained.

During a step 408, the graphic visual code with two reading levels, obtained during step 406, is represented graphically on a physical medium by printing or displayed on a computer medium such as a display screen or else memorized in a storage means.

In general, the secondary generation application can implement, during an optional step 410 performed before step 406, one or more algorithms for:

- encode the secondary information, and / or

to enrich the secondary information with a view, for example, to correcting errors during the reading of the graphical visual code according to the invention: in this case, the secondary generation application may, for example, comprise or be coupled to a correction code; n-ary error, or any other algorithm known in the state of the art.

- create a link between the primary information and the secondary information, and in particular generate at least some of the secondary information from the primary information.

FIGURE 5 is a schematic representation of a non-limiting example of a device for generating a graphical visual code according to the invention.

The device 500 comprises a primary generation application 502 for generating a graphical visual code from at least one primary pattern stored in a so-called primary base 504. The primary generation application 502 includes an algorithm for generating a graphical representation of primary information, denoted IP, from the primary pattern or patterns stored in the primary database 504. Such a primary generation application may for example be a QR code generation application.

The device 500 also comprises a secondary generation application 506 for generating at least one primary pattern enriched by superposition of at least one primary pattern stored in the primary base and at least one so-called secondary base 508 comprising at least one pattern secondary level previously determined. The secondary generation application 508 comprises an algorithm making it possible to generate a graphic representation of a secondary information item, denoted IS, from the enriched pattern (s) and the graphical visual code generated by the primary application.

The device 500 further comprises means for representing the enriched visual code 510 provided by the secondary generation application 506. Such representation means may be either a printing means or an electronic display means such as a display screen.

Alternatively, the representation means can be replaced by a storage means storing the graphical visual code.

FIGURE 6 is a schematic representation of a non-limiting example of a method of reading a graphical visual code according to the invention.

The method 600, shown in FIG. 6, comprises a step 602 for digitizing a graphic visual code according to the invention from a physical medium or from a display screen.

In a step 604, the digitized graphic visual code is then read by a primary reading application detecting each primary pattern. Such a primary reading application is known. This primary reading application deduces the primary information, for example the primary IP information, from the detected primary patterns and their spatial arrangements in the graphical visual code and / or their spatial arrangements between them.

Then, a secondary read application reads the secondary information from the secondary patterns in the graphical visual code. To do this, the secondary reading application performs a step 606 for detecting the secondary patterns present in the digitized graphic visual code during step 602. To do this, step 606 performs the following operations, for each primary pattern graphical visual code:

calculating a correlation value of said enriched primary pattern produced with said enriched primary pattern with each of the original secondary patterns previously stored in a secondary base, such as the base 508, for example with the Pearson correlation function;

classification of the identified patterns according to the relative values of the different correlations for each enriched pattern;

storage of the secondary pattern thus possibly identified with data relating to its spatial positioning in the graphical visual code;

Step 606 provides all the secondary patterns inscribed in the primary patterns of the graphical visual code, possibly with the spatial positioning of each secondary pattern in the graphical visual code.

During a step 608, the secondary reading application deduces the secondary information, for example the information IS of FIGURE 5, based on:

of all the secondary patterns detected during step 606,

a previously determined graphical coding / decoding algorithm, for example the coding / decoding algorithm determined in step 402 of the method 400 of FIG. 4.

In general, the secondary reading application may furthermore use, during an optional step 610, one or more algorithms for:

decoding the secondary information when the latter is coded during the generation of the graphical visual code, and / or

- correct errors: in this case, the secondary application can use an error correction code, for example n-ary.

Furthermore, the read method 600 of FIGURE 6 may comprise steps (not shown) of preprocessing the digitized graphic visual code, performed just after the scanning step 602, in order to determining the orientation and / or the size of the digitized visual code by any standard means for detecting and resampling with at least one linear sampling function.

FIGURE 7 is a schematic representation of a non-limiting example of a device for reading a graphical visual code according to the invention.

The reading device 700 of FIGURE 7 comprises a scanning means 702, such as a camera, a scanner or screen capture means, a graphic visual code from a hardware medium or a display screen. .

The device 700 further comprises a primary reading application 704 for reading a primary information, for example the primary information IP of FIGURE 5, from the primary patterns of a graphical visual code digitized by the digitizing means 702. such a primary reading application may for example be a QR code reading application.

Optionally, the reading device 700 may comprise a primary primary pattern base 504 used by the primary read application to read the primary information.

The device 700 also includes a secondary read application 706 for reading a secondary information, for example the secondary information IS of FIGURE 5, from at least one secondary pattern detected in the graphic visual code. For this purpose, the secondary reading application may comprise means configured to implement steps 606 and 608, and possibly step 610, of the reading method 600 of FIG. 6. To do this, the device 700 of FIG. FIGURE 7 comprises a secondary base, such as the base 508 of FIGURE 5, including all of the primary patterns that could be used to realize the graphical visual code digitized by the digitizing means 702. Of course, the examples given are in no way limiting. For example, the examples given concerning black and white QR codes, but the invention is neither limited to QR codes, nor limited to black and white codes and can be applied to all types of graphical visual codes.

Claims

A graphic visual code (200) composed of a plurality of graphic patterns (102), said primary patterns, whose spatial arrangement with each other represents a predetermined information (IP), called primary information, readable by means optical reading device executing a predetermined primary readout application (704), at least one of said primary patterns (202; 302-304), said enriched pattern, comprises at least one graphic pattern (308-310), said secondary pattern, representing information (IS), said secondary, and readable by an optical reading means executing a read application (706), said secondary, characterized in that the at least one secondary pattern is selected in a database (508 ), said secondary, comprising several different secondary patterns constituting an alphabet.

2. Code (200) according to the preceding claim, characterized in that the primary pattern (102) and the secondary pattern (308-310), constituting an enriched pattern (202; 302-304), are chosen so that the value a predetermined parameter calculated according to said primary pattern (102) and said enriched pattern (202; 302-304) satisfies a predetermined threshold value.

3. Code (200) according to any one of the preceding claims, characterized in that the primary (102) and secondary (308-310) units constituting an enriched unit (202; 302-304) are selected from whereby a relative density of said enriched pattern (202; 302-304) relative to said primary pattern (102) is greater than or equal to a threshold value of 0.5.

4. Code (200) according to any one of the preceding claims, characterized in that at least one, preferably each, secondary pattern (308-310) is selected from the base (508) secondary, and has a texture, a density and / or shape such that the ratio of:

a correlation value between said original version of the enriched primary pattern and said secondary pattern in said base secondary and another secondary pattern in said produced version of said code; and

a correlation value between the original version of the enriched primary pattern with said secondary pattern in said secondary base and said secondary pattern in a so-called produced version of said code;

has a ratio lower than or equal to a predetermined threshold, in particular

0.95.

5. Code (200) according to any one of the preceding claims, characterized in that at least one, preferably each, secondary pattern (308-310) is selected from the base (508) secondary, and has a texture, a density and / or a shape such that, when the code (200) is reproduced by a predetermined reproduction process comprising:

a digitization of a so-called produced version of said code obtained by printing on a physical medium or by displaying on a display screen, and

a representation of the digitized code by printing on a physical medium or representation on a display screen;

said secondary pattern (308-310) on the reproduced version of said code thus obtained can no longer be read by the secondary application (706).

6. Code (200) according to the preceding claim, characterized in that at least one, preferably each, secondary pattern (308-310) is chosen so that the ratio between:

a correlation value between the enriched primary pattern with said secondary pattern in the reproduced version of said code and the original version of said secondary pattern in the secondary base (508); and

a correlation value between the enriched primary pattern with said secondary pattern in the produced version of said code and the original version of said secondary pattern in the sub base (508); has a ratio less than or equal to a predetermined threshold, in particular 0.75.

7. Code (200) according to any one of the preceding claims, characterized in that it comprises a plurality of enriched primary units (202; 302-304), each comprising one or more secondary units (308-310), secondary information (IS) being determined according to all of said secondary patterns (308-310), and possibly according to their spatial arrangement in said code (200).

8. Code (200) according to any one of the preceding claims, characterized in that at least one, preferably each enriched primary pattern (202; 302-304) is binary.

The code (200) according to any one of the preceding claims, characterized in that it is in black and white, each secondary pattern (308-310) being chosen such that each enriched primary pattern (202; ) has a percentage of black pixel constant and equal to a predetermined value.

10. Code (200) according to any one of the preceding claims, characterized in that its primary patterns (102) form a QR code (100) or a bar code.

The method (400) for generating a graphical visual code (200) according to any one of the preceding claims, comprising the steps of:

- Generation (404), by a so-called primary generation application (502), of a so-called initial visual code (100) by spatial arrangement of a plurality of primary patterns (102) according to the primary information (IP), and

- inscription (406) by a so-called secondary generation application (506) of at least one secondary pattern (308-310) on at least one at least one of said primary patterns (102) of said initial visual code (100), depending on the secondary information (IS) and said initial visual code (100).

characterized in that the at least one secondary pattern is selected in a so-called secondary database (508) comprising a plurality of different secondary patterns constituting an alphabet.

12. Method (400) according to the preceding claim, characterized in that it comprises a step of generating the secondary information (IS) according to the primary information (IP).

Method (400) according to any one of claims 11 or 12, characterized in that the writing step (406) comprises a step of selecting, in a base (508), at least one secondary pattern (308-310) depending on the secondary information (IS), the secondary generation application (506).

14. A method of reading (600) a graphical visual code according to any one of claims 1 to 10, characterized in that it comprises the following steps:

reading (604) by the primary readout application (704) of the primary information (IP) from the graphical visual code,

reading (606-610) by the secondary readout application (706) of the secondary information (IS) from the graphical visual code, said reading comprising the following operations:

^■ identifying each primary pattern (102) in the graphic display code,

^■ for each primary pattern, determining a correlation value with the primary pattern enriched with each secondary pattern (308-310) of the base (508) of second patterns

(308-310), said determination identifying the secondary pattern (308-310) inscribed in said primary pattern (102) when said primary pattern (102) has a secondary pattern (308- ^■ determining, by the secondary readout application (706) of the secondary information (IS), based on the secondary reasons (308-310) identified and possibly their spatial arrangement.

15. Method (600) according to the preceding claim, characterized in that it further comprises a step of detecting a reproduction or not of the graphical visual code according to at least one correlation value and at least one predetermined threshold.