Method and apparatus for cancelling lighting variations in object recognition
First Claim
1. A method of cancelling lighting variations in a digital image of a specified class of objects, said method including the steps of:
- estimating lighting parameters and reliability for each pixel of said digital image using a stochastic model of the specified object class;
segmenting said digital image into regions having different lighting parameters;
distinguishing object details in said digital image from shadows in said digital image;
splitting and merging regions containing object details into nearest regions;
estimating predetermined lighting-parameter characteristics for each split and merged region; and
reconstructing said digital image based on said estimated lighting-parameter characteristics.
1 Assignment
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Accused Products
Abstract
A lighting normalisation method, apparatus and computer program product are disclosed. First, lighting parameters are estimated (110) optimally based on a shading model. After applying segmentation (120), each generated region is assigned are liability based on the stochastic model of that object. This reliability is used to distinguish (130) shadow from object detail. Regions are then further split and merged (140) according to these reliabilities. Finally, the lighting parameters of these regions are calculated and the object is reconstructed (150) to a normalised lighting condition. This technique can be used for an object recognition system, i.e., face recognition applications, as well as for image enhancement, image retrieval, machine vision and related regions.
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Citations
24 Claims
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1. A method of cancelling lighting variations in a digital image of a specified class of objects, said method including the steps of:
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estimating lighting parameters and reliability for each pixel of said digital image using a stochastic model of the specified object class;
segmenting said digital image into regions having different lighting parameters;
distinguishing object details in said digital image from shadows in said digital image;
splitting and merging regions containing object details into nearest regions;
estimating predetermined lighting-parameter characteristics for each split and merged region; and
reconstructing said digital image based on said estimated lighting-parameter characteristics. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. An apparatus for cancelling lighting variations in a digital image of a specified class of objects, said apparatus including:
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means for estimating lighting parameters and a reliability for each pixel of said digital image using a stochastic model of the specified object class;
means for segmenting said digital image into regions having different lighting parameters;
means for distinguishing object details in said digital image from shadows in said digital image;
means for splitting and merging regions containing object details into nearest regions;
means for estimating predetermined lighting-parameter characteristics for each split and merged region; and
means for reconstructing said digital image based on said estimated lighting-parameter characteristics. - View Dependent Claims (10, 11, 12, 13, 14, 15, 16)
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17. A computer program product having a computer usable medium having a computer readable program code means embodied therein for cancelling lighting variations in a digital image of a specified class of objects, said computer program product including:
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computer readable program code means for estimating lighting parameters and a reliability for each pixel of said digital image using a stochastic model of the specified object class;
computer readable program code means for segmenting said digital image into regions having different lighting parameters;
computer readable program code means for distinguishing object details in said digital image from shadows in said digital image;
computer readable program code means for splitting and merging regions containing object details into nearest regions;
computer readable program code means for estimating predetermined lighting-parameter characteristics for each split and merged region; and
computer readable program code means for reconstructing said digital image based on said estimated lighting-parameter characteristics. - View Dependent Claims (18, 19, 20, 21, 22, 23, 24)
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Specification