# US 2025/0148853 A1 · Method and system for the authentication of hologram protected identity documents > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2025/0148853 A1 - Document ID: US20250148853A1 - Status: Published application - Kind: A1 - Application number: 18/833,749 - Filed: 2023-01-28 - Published: 2025-05-08 - Earliest claimed: 2022-01-29 - Assignees: Imds Group Inc. - Applicants: Imds Group Inc. - Inventors: Nicole VINCENT; Camille KURTZ; Oumayma KADA; Cuong VAN KIEU - Web page: https://patentgrep.com/patent/US20250148853A1 ## CPC - G06V 30/40: Document-oriented image-based pattern recognition - G07D 7/12: Visible light, infrared or ultraviolet radiation - B42D 25/24: Passports - B42D 25/328: Diffraction gratings; Holograms - G06V 10/16: {using multiple overlapping images; Image stitching} - G06V 10/457: {by analysing connectivity, e.g. edge linking, connected component analysis or slices} - G06V 10/56: relating to colour - G06V 20/95: {Pattern authentication; Markers therefor; Forgery detection} - G07D 7/206: Matching template patterns - G06T 7/90: Determination of colour characteristics - G06V: IMAGE OR VIDEO RECOGNITION OR UNDERSTANDING - G07D: HANDLING OF COINS OR VALUABLE PAPERS, e.g. TESTING, SORTING BY DENOMINATIONS, COUNTING, DISPENSING, CHANGING OR DEPOSITING - B42D: BOOKS; BOOK COVERS; LOOSE LEAVES; PRINTED MATTER CHARACTERISED BY IDENTIFICATION OR SECURITY FEATURES; PRINTED MATTER OF SPECIAL FORMAT OR STYLE NOT OTHERWISE PROVIDED FOR; DEVICES FOR USE THEREWITH AND NOT OTHERWISE PROVIDED FOR; MOVABLE-STRIP WRITING OR READING APPARATUS - G06T: IMAGE DATA PROCESSING OR GENERATION, IN GENERAL ## Abstract A method and system for the authentication of hologram protected identity documents using, for example, a video obtained from a smartphone or tablet in natural light conditions, indoor or outdoor. From a first selection of pixels in frames of the video, based on pixel properties such as saturation and value, the shape of connected components and hues of the selected pixels are studied in order to detect the presence of a hologram. Furthermore, the hologram can be retrieved by an aggregation of image parts extracted from each of the frames. ## Claims ### Claim 1 A method for the authentication of a hologram protected document, the method comprising the steps of: a) obtaining at least two images of the document; b) identifying in each of the at least two images pixels having a saturation and a value above respective saturation and value threshold; c) building a set of identified pixels connected components from the identified pixels of step b) for each of the least two images; d) removing from the set of identified pixels connected components any connected components belonging to a porous structure; e) computing a number of hues present in each remaining connected component of the set of identified pixels connected components and normalizing the number of hues according to a size of each of the remaining connected component from the set of identified pixels connected components; f) removing from the remaining connected components of the set of identified pixels connected components any connected component associated with a normalized number of hues below a specified hue number value; g) determining the presence of a hologram by computing a difference between color features of the remaining connected components of the set of identified pixels connected components of different images of the at least two images; h) setting a document score by computing an average of all the computed differences; i) authenticating the hologram protected document when the document score is above a specified document score value. ### Claim 2 (depends on 1) A method for the authentication of a hologram protected document according to claim 1, wherein the document is an identity document. ### Claim 3 (depends on 2) A method for the authentication of a hologram protected document according to claim 2, wherein the identity document is selected from a group consisting of a passport and a consular card. ### Claim 4 (depends on 1, 2, 3) A method for the authentication of a hologram protected document according to any one of claims 1 to 3, wherein at step b) the saturation threshold and the value threshold are determined from respective saturation and value histograms. ### Claim 5 (depends on 4) A method for the authentication of a hologram protected document according to claim 4, wherein the saturation threshold and the value threshold are determined by choosing a significant minimum higher than the mean value of the corresponding saturation and value histograms. ### Claim 6 (depends on 1, 2, 3, 4, 5) A method for the authentication of a hologram protected document according to any one of claims 1 to 5, wherein step a) includes expressing the at least two images in the HSV colors space. ### Claim 7 (depends on 1, 2, 3, 4, 5, 6) A method for the authentication of a hologram protected document according to any one of claims 1 to 6, wherein step d) includes for each of the at least two images: obtaining a dilated set of connected components by applying dilation to the set of identified pixels connected components; each time a number of connected components of the set of identified pixels connected components present in a given connected component of the dilated set of connected components is above a specified connection number value, removing pixels of the given connected component of the dilated set of connected components from the set of identified pixels connected components. ### Claim 8 (depends on 7) A method for the authentication of a hologram protected document according to claim 7, wherein the specified connection number value at step d) is determined using a set of training images. ### Claim 9 (depends on 1) A method for the authentication of a hologram protected document according to claim 1, wherein the specified hue number value at step f) is determined using a set of training images. ### Claim 10 (depends on 1) A method for the authentication of a hologram protected document according to claim 1, wherein the specified document score value at step i) is determined using a set of training images. ### Claim 11 (depends on 1, 2, 3, 4, 5, 6, 7, 8, 9, 10) A method for the authentication of a hologram protected document according to any one of claims 1 to 10, wherein at step a) the at least two images are obtained by extracting frames from a video of the document. ### Claim 12 (depends on 11) A method for the authentication of a hologram protected document according to claim 11, wherein step g) if performed for all pairs of consecutive frames of the video. ### Claim 13 (depends on 11) A method for the authentication of a hologram protected document according to claim 11, wherein step g) if performed for pairs of distant frames of the video. ### Claim 14 (depends on 11, 12, 13) A method for the authentication of a hologram protected document according to any one of claims 11 to 13, further comprising the step of: j) recovering the hologram by aggregating pixels of the remaining connected components of the set of identified pixels connected components of each of the at least two images to which is applied an associated frame transform. ### Claim 15 (depends on 14) A method for the authentication of a hologram protected document according to claim 14, wherein a step j) the associated frame transform is a transform of a video frame corresponding to each of the at least two images during fixed frame registration. ### Claim 16 (depends on 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15) A method for the authentication of a hologram protected document according to any one of claims 1 to 15, wherein the steps are in the form of executable code for execution by a processor of a smartphone or tablet. ### Claim 17 A system for the authentication of a hologram protected document, the system comprising: a camera; at least one processor operatively connected to the camera, the at least one processor having an associated memory having stored therein processor executable code that when executed by the at least one processor performs the steps of: a) obtaining at least two images of the document from the camera; b) identifying in each of the at least two images pixels having a saturation and a value above respective saturation and value threshold; c) building a set of identified pixels connected components from the identified pixels of step b) for each of the least two images; d) removing from the set of identified pixels connected components any connected components belonging to a porous structure; e) computing a number of hues present in each remaining connected component of the set of identified pixels connected components and normalizing the number of hues according to a size of each of the remaining connected component from the set of identified pixels connected components; f) removing from the remaining connected components of the set of identified pixels connected components any connected component associated with a normalized number of hues below a specified hue number value; g) determining the presence of a hologram by computing a difference between color features of the remaining connected components of the set of identified pixels connected components of different images of the at least two images; h) setting a document score by computing an average of all the computed differences; i) authenticating the hologram protected document when the document score is above a specified document score value. ### Claim 18 (depends on 17) A system for the authentication of a hologram protected document according to claim 17, wherein the document is an identity document. ### Claim 19 (depends on 18) A system for the authentication of a hologram protected document according to claim 18, wherein the identity document is selected from a group consisting of a passport and a consular card. ### Claim 20 (depends on 17, 18, 19) A system for the authentication of a hologram protected document according to any one of claims 17 to 19, wherein at step b) the saturation threshold and the value threshold are determined from respective saturation and value histograms. ### Claim 21 (depends on 20) A system for the authentication of a hologram protected document according to claim 20, wherein the saturation threshold and the value threshold are determined by choosing a significant minimum higher than the mean value of the corresponding saturation and value histograms. ### Claim 22 (depends on 17, 18, 19, 20, 21) A system for the authentication of a hologram protected document according to any one of claims 17 to 21, wherein step a) includes expressing the at least two images in the HSV colors space. ### Claim 23 (depends on 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22) A system for the authentication of a hologram protected document according to any one of claims 1 to 22, wherein step d) includes for each of the at least two images: obtaining a dilated set of connected components by applying dilation to the set of identified pixels connected components; each time a number of connected components of the set of identified pixels connected components present in a given connected component of the dilated set of connected components is above a specified connection number value, removing pixels of the given connected component of the dilated set of connected components from the set of identified pixels connected components. ### Claim 24 (depends on 23) A system for the authentication of a hologram protected document according to claim 23, wherein the specified connection number value at step d) is determined using a set of training images. ### Claim 25 (depends on 17) A system for the authentication of a hologram protected document according to claim 17, wherein the specified hue number value at step f) is determined using a set of training images. ### Claim 26 (depends on 17) A system for the authentication of a hologram protected document according to claim 17, wherein the specified document score value at step i) is determined using a set of training images. ### Claim 27 (depends on 17, 18, 19, 20, 21, 22, 23, 24, 25, 26) A system for the authentication of a hologram protected document according to any one of claims 17 to 26, wherein in step a) the at least two images are obtained by extracting frames from a video of the document obtained by the camera. ### Claim 28 (depends on 27) A system for the authentication of a hologram protected document according to claim 27, wherein step g) if performed for all pairs of consecutive frames of the video. ### Claim 29 (depends on 27) A system for the authentication of a hologram protected document according to claim 27, wherein step g) if performed for pairs of distant frames of the video. ### Claim 30 (depends on 27, 28, 29) A system for the authentication of a hologram protected document according to any one of claims 27 to 29, further comprising the step of: j) recovering the hologram by aggregating pixels of the remaining connected components of the set of identified pixels connected components of each of the at least two images to which is applied an associated frame transform. ### Claim 31 (depends on 30) A system for the authentication of a hologram protected document according to claim 30, wherein a step j) the associated frame transform is a transform of a video frame corresponding to each of the at least two images during fixed frame registration. ### Claim 32 (depends on 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32) A system for the authentication of a hologram protected document according to any one of claims 17 to 32, wherein the camera and the at least one processor are provided by a smartphone or a tablet.