Method for correcting an image of at least one object presented at a distance in front of an imaging device and illuminated by a lighting system and an image pickup system for implementing said method

Patent metadata

Field	Value
Publication number	US-2016284068-A1
Application number	US-201615080176-A
Country	US
Kind code	A1
Filing date	Mar 24, 2016
Priority date	Mar 25, 2015
Publication date	Sep 29, 2016
Grant date	—

Abstract

An image correction method includes: estimating a 3D model of an object as when an imaging device takes an image of the object; calculating the light intensity of each point of a simulated image as it would be taken by the imaging device, using the estimated 3D model of the object, a model of illumination of the object illuminated by a lighting system that illuminates the object, a model of reflection on a surface of the object, and a model of the imaging device, to obtain a simulated image of the object; and correcting the taken image by modifying the light intensity of each point on the taken image or on at least one area of interest of the taken image, according to the light intensity of the corresponding point in the simulated image or the respective light intensities of points adjacent to the corresponding point in the simulated image.

First claim

1 ) A method for correcting an image taken by an imaging device of an object presented at a distance in front of said imaging device, said object being illuminated by means of a lighting system, wherein the method comprises the following steps:
estimating, from at least one image taken by a 3D image pickup apparatus, a 3D model of the object as it is time said imaging device takes said image, calculating the light intensity of each point of a simulated image as it would be taken by the imaging device, using said thus estimated 3D model of the object, a model of the illumination of the object illuminated by said lighting system, a model of reflection on a surface of the object and a model of said imaging device, in order to obtain a simulated image of said object, and correcting the image taken by said imaging device, consisting in modifying the light intensity of each point on the image actually taken by the imaging device or on at least one area of interest of the image actually taken by the imaging device, according to the light intensity of the corresponding point in the simulated image or the respective light intensities of points adjacent to said corresponding point in the simulated image.

2 ) The method for correcting an image according to claim 1 , wherein the correcting includes:
calculating, for each point of the image or of at least one area of the image taken by said imaging device, a correction factor that is a decreasing function of the light intensity of the corresponding point in the simulated image of said object, and modifying the light intensity of each point of the image or of at least one area of the image actually taken by said imaging device in proportion to said correction factor.

3 ) The method for correcting an image according to claim 2 , further comprising:
determining points on the simulated image for which the light intensity is above a maximum threshold, determining points on the simulated image for which the light intensity is below a minimum threshold, said correction step not being preformed for the points on the image taken by the imaging device corresponding to the points on the simulated image thus determined at step and at step.

4 ) The method for correcting an image according to claim 3 , further comprising:
creating a mask corresponding to the points thus determined at the determination steps so that subsequent image processings of the corrected image do not take into account the corresponding points on said corrected image.

5 ) The method for correcting an image according to claim 1 , wherein said step of determining said 3D model uses a stereoscopic method involving pairs of views taken by said 3D image pickup system, said 3D image pickup system consisting either of two cameras taking respectively the views of each pair simultaneously, or a camera taking the views of each pair at two different times.

6 ) The method for correcting an image according to claim 5 , wherein one or other or both of the two cameras of said 3D image pickup system constitutes said imaging device.

7 ) An image pickup system for delivering a corrected image of an image taken by an imaging device of an object presented at a distance in front of said imaging device, said object being illuminated by means of a lighting system, wherein the image pickup system is adapted for:
estimating, from at least one image taken by a 3D image pickup apparatus, a 3D model of the object as it is at the time said imaging device takes an image, image-simulation means consisting of calculating the light intensity of each point on a simulated image as it would be taken by the imaging device, using said 3D model estimated, a model of the illumination of the object by said lighting system, a model of reflection on a surface of an object and a model of said imaging device, in order to obtain a simulated image of said object, and correcting the image taken by said imaging device in order to modify the light intensity of each point on the image actually taken by the imaging device or on at least one area of interest of the image actually taken by the imaging device, according to the light intensity of the corresponding point in the simulated image or the respective light intensities of points adjacent to said corresponding point in the simulated image.

8 ) The image pickup system according to claim 7 , wherein the image pickup system is further adapted for:
calculating, for each point on the image or on at least one area of the image taken by said imaging device, a correction factor that is a decreasing function of the light intensity of the corresponding point in the simulated image of the said object, and modifying the light intensity of each point on the image or at least one area of the image actually taken by said imaging device in proportion to said correction factor.

9 ) The image pickup system according to claim 8 , wherein the image pickup system is further adapted for:
determining points on the simulated image for which the light intensity is above a maximum threshold, determining points on the simulated image for which the light intensity is below a minimum threshold, said correction means not taking into account the points on the image taken by the image corresponding to the points on the thus determined simulated image.

10 ) The image pickup system according to claim 9 , wherein the image pickup system is further adapted for:
creating a mask corresponding to the points thus determined by said determination means, said mask being designed so that processings of images subsequent to the corrected image do not take into account the corresponding points on said corrected image.

11 ) A computer program product embodying instructions that, when executed by a processor of an image pickup system, executing a method, the method comprising:
estimating, from at least one image taken by a 3D image pickup apparatus, a 3D model of the object as it is time said imaging device takes said image, calculating the light intensity of each point of a simulated image as it would be taken by the imaging device, using said thus estimated 3D model of the object, a model of the illumination of the object illuminated by said lighting system, a model of reflection on a surface of the object and a model of said imaging device, in order to obtain a simulated image of said object, and correcting the image taken by said imaging device, consisting in modifying the light intensity of each point on the image actually taken by the imaging device or on at least one area of interest of the image actually taken by the imaging device, according to the light intensity of the corresponding point in the simulated image or the respective light intensities of points adjacent to said corresponding point in the simulated image.

12 ) Storage means that stores a computer program comprising instructions for the implementation, by a central unit of an image pickup system, of a method according to claim 1 , when said program is executed by said processer.

Assignees

• Morpho

Inventors

• Rouh Alain
• Beaudet Jean
• Dura Jeremy
• Rostaing Laurent

Classifications

• G06T7/593

  from stereo images · CPC title

• G06T7/521

  from laser ranging, e.g. using interferometry; from the projection of structured light · CPC title

• G06T2207/20012

  Locally adaptive · CPC title

• G06T7/514

  from specularities · CPC title

• G06T2207/10012

  Stereo images · CPC title