Determination of an illuminant of digital color image by segmentation and filtering
First Claim
1. An automatic method for determining an illuminant of a digital color image, the method comprising the steps of:
- a) segmenting an image into regions of homogeneous color;
b) extracting the regions from the segmented image that are non-compliant with a dichromatic reflection model;
c) for each region not extracted from the image, determining from chromatic coordinates of pixels forming said region, a straight line representing a direction of a chromatic convergence;
d) determining a most probable convergence point of a set of the straight lines obtained in said step c); and
e) determining chromatic coordinates of the most probable convergence point obtained in said step d) and representing an illuminant of the color image.
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Abstract
The present invention is in the technical field of analyzing and processing digitized color images. More specifically it relates to a method of determining the chromaticity of an illuminant (white reference) of a color image representing a natural scene of objects or entities. The present invention uses the principle of the constancy of dichromatic color, but it also uses spatial color segmentation of the image and relevant filtering to select the regions of the image to be analyzed, that is to extract the analyzed regions non-compliant with the chromatic model. The invention is applicable for improving the performance of the means of analysis and recognition of the shapes of objects in an image.
39 Citations
12 Claims
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1. An automatic method for determining an illuminant of a digital color image, the method comprising the steps of:
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a) segmenting an image into regions of homogeneous color;
b) extracting the regions from the segmented image that are non-compliant with a dichromatic reflection model;
c) for each region not extracted from the image, determining from chromatic coordinates of pixels forming said region, a straight line representing a direction of a chromatic convergence;
d) determining a most probable convergence point of a set of the straight lines obtained in said step c); and
e) determining chromatic coordinates of the most probable convergence point obtained in said step d) and representing an illuminant of the color image. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
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Specification