Method for identifying a sign on a deformed document

Patent metadata

Field	Value
Publication number	US-2016104039-A1
Application number	US-201514878837-A
Country	US
Kind code	A1
Filing date	Oct 8, 2015
Priority date	Oct 10, 2014
Publication date	Apr 14, 2016
Grant date	—

Abstract

This invention relates to a method for identifying a sign on an image of a document that can be deformed comprising:
an acquisition (E 1 ) of said digital image of said document;
a determination (E 2 ) in the acquired image of at least one candidate sign region using an image segmentation algorithm,
for each candidate sign region, a calculation (E 3 ) of a signature comprising a piece of information concerning the location in the acquired image of said candidate sign region and a region descriptor concerning the local characteristics of the image in said region,
an identification (E 4 ) of a sign on the image of the document using the calculated signatures comprising jointly a comparison (E 41 ) of the calculated signatures with reference signatures concerning sign regions of document models, said comparison being carried out according to a geometric deformation model of said document, and an estimation (E 42 ) according to said comparison of said geometric deformation model.

First claim

1 . Method for identifying at least one sign on at least one image of a document that can be deformed,
said method being implemented by a data processing device able to be connected to a first storage device and characterised in that it comprises steps of: acquiring (E 1 ) said at least one digital image of said document; determining (E 2 ) in the acquired image at least one sub-part of the image acquired, referred to as candidate sign region, using an image segmentation algorithm, for each candidate sign region, calculating (E 3 ) a signature comprising a piece of information concerning the location in the acquired image of said candidate sign region and a region descriptor concerning the local characteristics of the image in said region, identifying (E 4 ) at least one sign on said at least one image of said document using the calculated signatures, said step of identifying comprising jointly a comparison (E 41 ) of the calculated signatures with reference signatures concerning sign regions of document models stored in the first storage device, said comparison being carried out according to a geometric deformation model of said document, and an estimation (E 42 ) according to said comparison of said geometric deformation model.

2 . Method of identification as claimed in claim 1 , wherein for each candidate sign region:
said step of comparing comprises: a comparison of the signature calculated for said region with said reference signatures stored in said first storage device, a putting into correspondence of the calculated signature with a reference signature according to said comparison and to a geometric deformation model of the current document stored in a second storage device connected to said data processing device, in such a way as to identify said candidate sign region, and said step of estimating (E 42 ) comprises: an estimating of a new geometric deformation model of said document from said current geometric deformation model and from said correspondence, a storing in the second storage device of said new deformation model as a current deformation model.

3 . Method of identification according to claim 1 , wherein said document is a game ticket or an identity document.

4 . Method of identification according to claim 1 , wherein a sign to be identified is a geometric figure, a character, a group of characters or a graphical element.

5 . Method of identification according to claim 1 , wherein a sign to be identified is a pattern delimited by a closed contour.

6 . Method of identification according to claim 3 , wherein a sign to be identified is a box, a circle, a star or an alphanumeric character or a specific pattern of the issuing country of an identity document.

7 . Method of identification according to claim 3 , wherein a signature further comprises information on the scale.

8 . Method of identification according to claim 3 , wherein a descriptor of a sign region relates to information on the contour and/or on the content of said sign region.

9 . Method of identification according to claim 3 , wherein the deformation model is determined using an inverse distance weighting algorithm or an splines interpolation algorithm.

10 . Computer programme product comprising code instructions for the executing of a method of identification as claimed in claim 3 when this programme is executed by a processor.

11 . Device for identifying at least one sign on at least one image of a document that can be deformed,
characterised in that it comprises a data processing device able to be connected to a first storage device comprising: a module for acquiring said at least one digital image of said document; a module for determining in the acquired image of at least one subpart of the image acquired, referred to as candidate sign region, using an image segmentation algorithm, a module for calculating a signature for each candidate sign region comprising a piece of information concerning the location in the acquired image of said candidate sign region and a region descriptor concerning the local characteristics of the image in said region, a module for identifying at least one sign on said at least one image of said document using the calculated signatures, said module for identifying comprising a module for comparing of the calculated signatures with reference signatures concerning sign regions of document models stored in said first storage device, according to a geometric deformation model of said document, and a module for the joint estimating of said geometric deformation model according to said comparison.

Assignees

• Morpho

Inventors

• Rouh Alain
• Beaudet Jean
• Rostaing Laurent

Classifications

• G06V30/414 Primary

  Extracting the geometrical structure, e.g. layout tree; Block segmentation, e.g. bounding boxes for graphics or text · CPC title

• G06F18/22

  Matching criteria, e.g. proximity measures · CPC title

• G06V10/225

  based on a marking or identifier characterising the area · CPC title

• G06V10/20

  Image preprocessing · CPC title

• G06V10/247

  by affine transforms, e.g. correction due to perspective effects; Quadrilaterals, e.g. trapezoids · CPC title