WO2018065381A1

WO2018065381A1 - Method for reading a series of two-dimensional barcodes arranged on a support, associated computer program product and reading device

Info

Publication number: WO2018065381A1
Application number: PCT/EP2017/075026
Authority: WO
Inventors: Marc Cohen; Brian GIANNINI; Sylvain BLONDE; Djilali BELKHITER
Original assignee: In-Idt
Priority date: 2016-10-06
Filing date: 2017-10-03
Publication date: 2018-04-12
Also published as: FR3057375A1; FR3057375B1

Abstract

This method enables reading of a series (12) of two-dimensional barcodes (20A,...,20D) arranged on a support (14), the series comprising at least two separate two-dimensional barcodes (20A,...,20D), each barcode (20A,...,20D) comprising a header and a body comprising useful information. The method comprises steps of taking an image of the support, determining at least one contour on the image, creating a rectangular shape corresponding to a minimum surface encompassing the shape corresponding to each contour, determining the content of each rectangular shape in order to read the header of the corresponding barcode (20A,...,20D), determining the total number of barcodes (20A,...,20D) in the series (12) and regenerating a data file encoded by the series (12).

Description

METHOD FOR READING A SERIES OF BAR CODES

TWO-DIMENSIONAL ARRANGEMENTS ON A SUPPORT, PROGRAM PRODUCT

The present invention relates to a method of reading a series of two-dimensional bar codes arranged on a support, a computer program product and a reading device associated therewith.

The support is in particular an identification document such as an identity card, a driving license or a passport.

It is known to provide on such a type of support, a barcode, including a two-dimensional codes such as a QRCode (English "Quick Response Code") or Datamatrix type code.

This barcode encodes, for example, identification data such as biometric information or the civil status information of the wearer.

Also known is document WO 2015/075053 A1 describing an identity document for storing a large number of data in the form of a series of barcodes.

In particular, such a series of barcodes comprises at least two distinct barcodes which encode complementary parts of an identification file. This identification file includes all the personal data stored on the document possibly in encrypted form.

To reconstruct this identification file, it is necessary to read and decode each of the barcodes in the series.

In general, the reading is carried out by a suitable reading device such as a scanner or any other device including in particular means of taking pictures. To obtain the identification file, this device implements a method of reading barcodes for each of the barcodes present on the document.

However, existing reading devices can not read a series of barcodes simultaneously. It is often necessary to read and memorize each barcode in isolation to reconstruct the corresponding data file. A processing of a series of images is then necessary. Moreover, the existing reading devices do not make it possible to read the high density bar codes in difficult reading conditions such as lack of brightness, imperfections of the printing, etc.

The present invention aims to provide a reading device and a read method implemented by this device for simultaneous reading of a series of bar codes including high density, and this in difficult reading conditions.

To this end, the subject of the invention is a method of reading a series of two-dimensional bar codes arranged on a support, the series comprising at least two distinct two-dimensional bar codes, each barcode comprising:

a header determining this barcode uniquely in the series and including the total number of barcodes in the series; and

a body containing useful information of this barcode;

the useful information of all the barcodes of the series forming complementary parts of a data file encoded by the series;

the process comprising the following steps:

- taking an image of the support;

- determining on the image at least one contour encompassing a shape;

for the or each determined contour, creating a rectangular shape corresponding to a minimum surface encompassing the shape corresponding to this contour;

- for the or each rectangular shape created, determining the content of this rectangular shape and when the rectangular shape contains a barcode:

+ reading the header of this barcode;

+ when the header has not yet been stored, storing the header and the body of this barcode;

- Determination of the total number of barcodes in the series and when this number corresponds to the number of stored stubborn, reconstitution of the data file encoded by the series using the useful information contained in the stored bodies. According to other advantageous aspects of the invention, the method comprises one or more of the following characteristics, taken in isolation or in any technically possible combination:

the method further comprises a step of applying a filter configured to reduce noises on the image of the support and / or of a filter configured to associate with each pixel of the image one of the colors chosen from two predetermined colors, said step following the step of taking the corresponding image;

the method further comprises for the or each rectangular shape created, a verification step of this rectangular shape comprising comparing the surface of this shape with a reference surface, said rectangular shape being eliminated from the consideration when the difference between said surfaces is greater than a first predetermined threshold;

the method further comprises for the or each rectangular shape created, a verification step of this rectangular shape comprising the comparison of the width and the length of this rectangular shape, said rectangular shape being eliminated from the consideration when the difference between said width and said length is greater than a second predetermined threshold;

the method further comprises a step of applying a sharpness filter to the or each rectangular shape created;

the step of determining the content of the or each rectangular shape comprises the transformation of this form into binary data;

the step of determining the total number of headings in the series is implemented during the step of storing the header of one of the barcodes of the series, said number being determined from the header of the corresponding barcode;

said process steps are reiterated again when, during a previous iteration, the number of memorized stubs is less than the total number of barcodes in the series;

- each barcode is according to the QRCode standard or the Datamatrix standard;

- the medium is a physical or virtual identification document;

the data file is encrypted according to an encryption technique, the method further comprising a step of decrypting the data file; implementing a decryption technique complementary to said encryption technique; and

the method further comprises displaying results of execution of at least some of its steps in superposition of the image of the support.

The invention also relates to a computer program product comprising software instructions which, when implemented by computer equipment, implement the method as described above.

The invention also relates to a device for reading a series of two-dimensional bar codes arranged on a support, implementing the method as described above.

These features and advantages of the invention will become apparent on reading the description which follows, given solely by way of nonlimiting example, and with reference to the appended drawings, in which:

- Figure 1 is a schematic view of a reading device of a series of two-dimensional bar codes arranged on a support according to the invention;

FIG. 2 is a schematic view of the support of FIG. 1;

FIG. 3 is a flowchart of a reading method according to the invention, the method being implemented by the reading device of FIG. 1; and

FIGS. 4 and 5 are diagrammatic views of a human-machine interface illustrating the implementation of different steps of the method of FIG. 3.

The reading device 10 of FIG. 1 makes it possible to read a series 12 of barcodes. This series 12 is arranged on a support 14 which is illustrated in greater detail in FIG.

With reference to this FIG. 2, this support 14 is an identity document such as a national identity card of rectangular shape made for example of a sheet of cardboard or of polymer.

The support 14 comprises a front face 1 6A and a rear face 1 6B. Each of these faces is printed.

The front face 1 6A comprises, for example, a photograph of the wearer as well as civil status information written in a letter of printing. This information is for example the surname, first name, date of birth, nationality of the carrier, etc. The rear face 1 6B comprises other information 19 concerning the wearer such as his address.

The series of bar codes 12 is arranged on the rear face 1 6B, for example below the information 19.

According to an alternative embodiment not illustrated, the support 14 is in the form of any other printed document or virtual. In the latter case, the support 14 is displayed on a suitable display screen such as the screen of a mobile phone.

The series of bar codes 12 makes it possible to encode on the medium 14 a data file.

This file presents, for example, an identification file F | _D comprising the civil status information 18, the information 19 as well as the carrier's biometric information.

The biometric information includes a photograph of the wearer, his fingerprints, etc.

This file F | For example, _D is encrypted according to an asymmetric encryption technique, in particular of the RSA type using a private key. This key is known by the authorities who issued the identity document.

The series of bar codes 12 comprises a plurality of two-dimensional barcodes corresponding to complementary parts of the file F | _D.

In Fig. 2, the barcode series 12 has four barcodes 20A through 20D.

Each barcode 20A to 20D is square in shape so that the length of each of its sides is between 1 and 3 cm.

The barcodes 20A to 20D are spaced apart by an interval 24, the width of which is for example between 1 and 5 mm and preferably substantially equal to 2 mm. This interval forms a blank space for marking.

The barcodes 20A-20D are aligned so that their contiguous sides extend parallel to each other and adjacent sides to adjacent sides extend in line with one another.

Each barcode 20A to 20D is implemented for example according to the QRCode standard or the Datamatrix standard. Such a barcode preferably has a maximum capacity of 2953 bytes and has 177x177 points. This code- bars for example meets the ISO / IEC 18004 standard. Such a bar code is said to have a high density.

In general, a two-dimensional high density bar code means a two-dimensional bar code comprising points of size less than or equal to 0.2 mm.

Each barcode 20A to 20D encodes a header and a body.

The body of each barcode 20A to 20D includes useful information corresponding to a portion of the file F | _D. The file F | _D is thus formed of the set of useful information of all the barcodes 20A to 20D.

The header of each barcode 20A-20D includes a unique identifier of this barcode 20A-20D in the series 12 and the total number of barcodes in the series.

Each of the bar codes 20A to 20D of the series 12 is for example generated using techniques described in WO 2015/075053 A1.

These techniques include cutting the file F | _D in four sub-files of identical size whose concatenation gives the file F | _D.

Then, each of these subfiles is transformed into a graphic element according to a standard such as QRCode or Datamatrix, that is to say that each subfile is transformed into a matrix of two-color points.

Finally, each of these matrices is printed on the support 14.

With reference to FIG. 1, the reading device 10 comprises an imaging module 31, a processing module 33, a storage module 35 and a display module 37.

The reading device 10 is for example a mobile phone or any other electronic device comprising the aforementioned modules.

The image taking module 31 is able to take images including the medium 14 in the form of photographs or in the form of a video. The imaging module 31 has for example a camera having a lens integrated in the reading device 10.

The storage module 35 is able to store digital data and in particular calculation software implementing at least some of the steps of the reading method described below. The processing module 33 comprises for example a processor capable of executing the software stored in the storage module 35.

The display module 37 is for example a display screen capable of displaying the results of execution of at least some of the software stored in the storage module 35.

The reading method according to the invention will now be described with reference to FIG. 3 presenting a flowchart of its steps.

Initially, the medium 14 and the reading device 10 are provided. The reading device 10 is manipulated by an operator wishing to read the identification file F | _D encoded by the barcode series 12.

Thus, during the initial step 1 10, the operator activates the operation of the imaging module 31 and approaches the rear face 1 6B of the support 14 towards the objective of the imaging module 31.

In the next step 120, the imaging module 31 takes an image of the support 14 and in particular the part of the rear face 1 6B of this support comprising the series 12 of barcodes 20A to 20D.

In the following step 122, the imaging module 31 transmits the image taken to the processing module 33.

According to an alternative embodiment, this image is also transmitted to the module of the display 37 which then displays this image to the operator.

During the same step, the processing module 33 implements a software providing an initial processing of the image.

In particular, such an initial processing comprises the representation of the image in the matrix form allowing the analysis of this image, the cutting of the matrix obtained in delimited zones, etc.

In the next step 124, the processing module 33 implements software applying filters on the image.

In particular, during this step, the corresponding software applies a filter configured to reduce noises on the image and to detect contours on this image.

Such a filter is known as "Canny" and consists of applying a Gaussian filter to make the image smoother to reduce noise. Then, contours are detected by analyzing the intensity gradients of the image. Then, the corresponding software applies a filter configured to associate with each pixel of the image either the white color or the black color.

Such a filter is known under the name of "Threshold" and comprises the comparison of the intensity of each pixel of the image with respect to a threshold which is equal, for example, to the average of the intensities of the zones situated around the zone. analyzed.

This filter then comprises the association of either the white color or the black color at each pixel as a function of the position of the intensity of this pixel with respect to the threshold.

In the next step 126, the processing module 33 implements the contour search software on the image.

In particular, this software searches for all contours encompassing a shape on the image and stores each contour found in the storage module 35.

When during this step 126, at least one contour has been found, the processing module 33 passes in step 128 to the execution of the following step 132. In the opposite case, during the step 128, the processing module 33 returns to the execution of the step 120 described previously.

In step 132, the processing module 33 implements software configured to create a rectangular shape for each contour.

In particular, such a rectangular shape corresponds to a minimum surface encompassing the shape corresponding to this contour.

In the next step 134, the processing module 33 implements software configured to check the validity of each rectangular shape.

In particular, a rectangular shape is considered valid when the difference between its surface and a reference surface is less than a first predetermined threshold.

The reference surface is for example between 1 and 9 cm ² .

In this case, the value of the first predetermined threshold is for example equal to 1 cm ² . The value of the first threshold is configurable.

A rectangular shape is considered valid when moreover, the difference between its width and its length is less than a second predetermined threshold.

In this case, the value of the second predetermined threshold is for example equal to 0.1 cm. The value of the second threshold is configurable. Then, the processing module 33 eliminates from consideration all the rectangular shapes that are not valid.

In the next step 135, the processing module 33 determines whether there is at least one valid rectangular shape.

When this is the case, the processing module 33 adds to each valid rectangular shape a margin around this form and proceeds to step 136. This margin is less than, for example, 0.1 cm. The value of this margin is configurable.

In the opposite case, the processing module goes back to step 120.

According to an alternative embodiment, when the image is displayed by the display module, at the end of this step 135, the display module 37 superimposes an image on a frame corresponding to each valid rectangular shape.

In step 136, the processing module 33 implements software configured to apply a sharpness filter.

In particular, during this step, the corresponding software applies a sharpness filter for each of the valid rectangular shapes. This filter is to create a more blurry image than the original one, and then subtract the created image from that original image.

Thus, at the end of this step, rectangular shapes sharper than the original ones are obtained.

In the next step 140, the processing module 33 implements, for each rectangular shape, a software for decoding a barcode included in this form.

In particular, during this step, the decoding software forms a barcode from each rectangular shape. This decoding is performed according to the QRCode standard or the Datamatrix standard.

Then, in the following step 142, the processing module 33 implements a barcode verification software obtained.

In this step, when a barcode obtained is not valid or when the corresponding rectangular shape could not be decoded, the processing module 33 still implements steps 136 and 140 for the form corresponding rectangular by increasing in particular the brightness of this form.

In particular, the processing module 33 repeats steps 136 and 140 by checking in step 141 whether the iteration number has reached a predetermined maximum number of iterations.

If this is the case, that is to say if the barcode obtained is still not valid or if the corresponding rectangular shape could not be decoded, the processing module 33 eliminates from consideration this form. and go to step 120.

In the next step 143, the processing module 33 determines whether at least one valid barcode has been obtained in the previous decode step 140.

When this is the case, the processing module 33 goes to step 144. In the opposite case, the processing module 33 goes back to step 120.

In step 144, the processing module 33 implements a software for reading the headers.

In particular, during this step, this software reads the headers of each valid barcode and compares these headers with a list of stubborn stored in the storage module 35.

Then in this step, this software eliminates from consideration all barcodes whose headers are present in the list.

If at the end of this step all the bar codes are eliminated, the processing module goes back to step 120.

In the opposite case, that is to say if there is at least one barcode whose header is not present in the list, the processing module 33 proceeds to the next step 146.

During this step 146, the processing module 33 stores the header of each non-eliminated barcode in the list of headings and implements a software for reading the body of this barcode.

Then, the processing module 33 stores in the storage module 35 the useful information contained in each body. Then, the processing module 33 implements a software that makes it possible to determine the total number of barcodes in the series 12. This software determines this number by using one of the headers stored in the storage module 35.

According to an alternative embodiment, when the image is displayed by the display module, at the end of this step 146, the display module 37 superimposes the rectangular shape whose barcode has been decoded, a corresponding symbol.

In the next step 148, the processing module 33 implements software configured to compare the number of stubborn items stored in the list and the total number of barcodes.

When the number of stubborn stored is less than the total number of barcodes, the processing module 33 goes back to step 120.

In the opposite case, the processing module 33 proceeds to step 150.

In step 150, the processing module 33 implements software configured to reconstitute the identification file F | _D from all the useful information stored in the storage module 35 and from the bodies of the corresponding barcodes.

In the following step 152, the processing module 33 implements decryption software for decrypting the identification file obtained F | _D using in particular the corresponding private key.

In the next step 154, the processing module 33 transmits to the display module 37 the decrypted file which then displays the contents of this file on the corresponding display screen.

Figures 4 and 5 illustrate an example of a man-machine interface used in the implementation of the method described above. This interface is implemented by the display module 37 and ensures a fast reading of several bar codes in a single target.

Thus, FIGS. 4 and 5 illustrate a display zone 50 comprising a sighting zone 52 and a control zone 54.

In the control zone 54, the display module 37 is able to display control commands and, in particular, control commands for the operation of the imaging module 31. So, for example, these commands allow you to force a focus in a given location, manually.

In the area of sight 52, the display module 37 is able to display the image taken by the image taking module 31 and a result area 56 in superposition of said image.

In the result zone 56, the display module 37 is able to display execution results of at least some intermediate steps of the method.

Thus, in FIG. 4, the result zone 56 displays four digits corresponding to four outlines identified during step 128.

In Fig. 5, the result area 56 displays four symbols indicating successful decoding of four barcodes corresponding to the four identified outlines. These symbols are displayed for example at the end of step 143.

It is conceivable that the invention has a number of advantages.

Indeed, the method according to the invention makes it possible to read a series of barcodes simultaneously, even under difficult reading conditions such as lack of brightness, imperfections in printing, and so on.

In practice, taking a single image is necessary to read the entire series of barcodes. This has been made possible by a special treatment of the image facilitating reading. This treatment includes the application of several filters improving the readability of the image.

If, however, all the barcodes could not be read with the capture of a single image, the reading process makes another decision without any particular action of the operator being necessary.

Finally, the method can be implemented in particular by a mobile phone equipped with a camera. This then makes it possible to read a series of simple and reliable bar codes while using currently available means.

Claims

1. A method of reading a series (12) of two-dimensional bar codes (20A, ..., 20D) arranged on a support (14), the series comprising at least two two-dimensional bar codes (20A, ..., 20D) ), each barcode (20A, ..., 20D) comprising:

a header defining this barcode (20A, ..., 20D) uniquely in the series (12) and comprising the total number of barcodes (20A, ..., 20D) in the series (12) ; and

a body comprising useful information of this barcode (20A, ..., 20D);

the useful information of all the bar codes (20A, ..., 20D) of the series (12) forming complementary parts of a data file (FID) encoded by the series (12);

the process comprising the following steps:

- taking (120) an image of the support;

- determining (126) on the image of at least one contour encompassing a shape;

for the or each determined contour, creation (132) of a rectangular shape corresponding to a minimum surface encompassing the shape corresponding to this contour;

for the or each rectangular shape created, determining (140) the contents of this rectangular shape and when the rectangular shape contains a barcode (20A, ..., 20D):

+ reading (144) of the header of this barcode (20A, ..., 20D);

+ when the header has not yet been stored, storing (146) the header and the body of this barcode (20A, ..., 20D);

determination (146) of the total number of barcodes (20A, ..., 20D) in the series (12) and when this number corresponds to the number of stored stubs, reconstitution of the data file (FID) encoded by the series (12) using the useful information contained in the stored bodies.

The method of claim 1, further comprising a step (124) of applying a filter configured to reduce noise on the image of the medium (14) and / or a filter configured to associate with each pixel one of the colors chosen from two predetermined colors, said step following the step (120) of taking the corresponding image.

3. The method of claim 1 or 2, further comprising for the or each rectangular shape created, a step (134) of verification of this rectangular shape comprising comparing the surface of said shape with a reference surface, said rectangular shape. being eliminated from consideration when the gap between said surfaces is greater than a first predetermined threshold.

4. A method according to any one of the preceding claims, further comprising for the or each rectangular shape created, a step (134) of verification of this rectangular shape comprising the comparison of the width and the length of this rectangular shape, said rectangular shape being eliminated from the consideration when the difference between said width and said length is greater than a second predetermined threshold.

5. Method according to any one of the preceding claims, comprising a step (136) of applying a sharpness filter to the or each rectangular shape created.

The method of any of the preceding claims, wherein the step (140) of determining the content of the or each rectangular shape comprises transforming that form into binary data.

The method of any one of the preceding claims, wherein the step (146) of determining the total number of stubs in the series is performed in step (146) of storing the header of one of the bar codes (20A, ..., 20D) of the series (12), said number being determined from the header of the corresponding barcode (20A, ..., 20D).

A method according to any one of the preceding claims, wherein said process steps are reiterated again when on a previous iteration the number of stored stubs is less than the total number of barcodes in the series.

The method of any one of the preceding claims, wherein each barcode (20A, ..., 20D) is according to the QRCode standard or the Datamatrix standard.

The method of any one of the preceding claims, wherein the medium (14) is a physical or virtual identification document.

1 1. A method according to any one of the preceding claims, wherein the data file (F | _D ) is encrypted according to an encryption technique, the method further comprising a step (152) of decrypting the data file implementing a technique decryption complementary to said encryption technique.

The method of any of the preceding claims, further comprising displaying performance results of at least some of its steps in superposition of the image of the medium (14).

A computer program product comprising software instructions which, when implemented by computer hardware, implement the method of any one of the preceding claims.

14. Device (10) for reading a series (12) of two-dimensional bar codes (20A, ..., 20D) arranged on a support (14), implementing the method according to any one of claims 1 at 12.