Techniques for modifying image field data obtained using illumination sources
First Claim
Patent Images
1. A method for correcting image data of a scene by a digital camera, the method comprising the acts of:
- capturing a first image of the scene corresponding to a first illumination level;
capturing a second image of the scene corresponding to a second illumination level, different from the first illumination level and having a resolution that is relatively lower than the first image;
determining correction factors, for a non-uniform illumination area of the first image based on image data of the first and second images, wherein the correction factors are determined for one or more representative pixels, wherein the correction factors are determined by the formula;
IC[x,y]=Y/X(a[x,y]−
b[x,y]), where IC[x,y] is an illumination correction as a function of a position (x,y) within an object field, b[x,y] is an intensity as a function of the position (x,y) of an image data point of interest in an image data set captured at illumination level X, where X is a first artificial illumination level, a[x,y] is an intensity as a function of the position (x,y) of an image data point in an image data set of interest captured at illumination level Y, where Y is a second artificial illumination level, and wherein Y is greater than X; and
applying the correction factors to the non-uniform illumination area of the first image to obtain an illumination corrected image, wherein the correction factors are applied to one or more pixels associated with the non-uniform illumination area of the first image based on position of a pixel relative to at least one of the representative pixels.
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Abstract
Techniques for modifying data of an image that can be implemented in a digital camera, video image capturing device and other optical systems are provided to correct for non-uniform illumination and/or effects of saturation appearing in data obtained using one or more artificial illumination sources. In an implementation, correction factors are derived using data from at least two images that have been captured with different illumination levels of the object scene and close in time to the capture of the image of interest. Typically, the image of interest is of higher resolution than at least one of the at least two images.
17 Citations
27 Claims
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1. A method for correcting image data of a scene by a digital camera, the method comprising the acts of:
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capturing a first image of the scene corresponding to a first illumination level; capturing a second image of the scene corresponding to a second illumination level, different from the first illumination level and having a resolution that is relatively lower than the first image;
determining correction factors, for a non-uniform illumination area of the first image based on image data of the first and second images, wherein the correction factors are determined for one or more representative pixels, wherein the correction factors are determined by the formula;
IC[x,y]=Y/X(a[x,y]−
b[x,y]), where IC[x,y] is an illumination correction as a function of a position (x,y) within an object field, b[x,y] is an intensity as a function of the position (x,y) of an image data point of interest in an image data set captured at illumination level X, where X is a first artificial illumination level, a[x,y] is an intensity as a function of the position (x,y) of an image data point in an image data set of interest captured at illumination level Y, where Y is a second artificial illumination level, and wherein Y is greater than X; andapplying the correction factors to the non-uniform illumination area of the first image to obtain an illumination corrected image, wherein the correction factors are applied to one or more pixels associated with the non-uniform illumination area of the first image based on position of a pixel relative to at least one of the representative pixels. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13)
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14. A digital camera comprising:
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a sensor configured to capture image data; a flash illumination device configured to illuminate a scene with at least one level of illumination; and a processor coupled to the sensor and the flash illumination device, the processor configured to receive a first image of the scene corresponding to a first illumination level; receive a second image of the scene corresponding to a second illumination level, different from the first illumination level and having a resolution that is relatively lower than the first image; determine correction factors for a non-uniform illumination area of the first image based on image data of the first and second images, wherein the correction factors are determined for one or more representative pixels, wherein the correction factors are determined by the formula;
IC[x,y]=Y/X(a[x,y]−
b[x,y]), where IC[x,y] is an illumination correction as a function of a position (x,y) within an object field, b[x,y] is an intensity as a function of the position (x,y) of an image data point of interest in an image data set captured at illumination level X, where X is a first artificial illumination level, a[x,y] is an intensity as a function of the position (x,y) of an image data point in an image data set of interest captured at illumination level Y, where Y is a second artificial illumination level, and wherein Y is greater than X; andapply the correction factors to the non-uniform illumination area of the first image to obtain an illumination corrected image, wherein the correction factors are applied to one or more pixels associated with the non-uniform illumination area of the first image based on position of a pixel relative to at least one of the representative pixels. - View Dependent Claims (15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26)
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27. A method for correcting image data of a scene by a digital camera, the method comprising the acts of:
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capturing a first image of the scene corresponding to a first illumination level; capturing a second image of the scene corresponding to a second illumination level different from the first illumination level and having a resolution that is relatively lower than the first image; acquiring an image data set of interest based on the first and second illumination levels, the image data set of interest associated with a non-uniform illumination area of the first image; determining correction factors for the image data set of interest based on image data of the first and second images, wherein the correction factors are determined for one or more representative pixels, wherein the correction factors are determined by the formula;
IC[x,y]=Y/X (a[x,y]−
b[x,y]), where IC[x,y] is an illumination correction as a function of a position (x,y) within an object field, b[x,y] is an intensity as a function of the position (x,y) of an image data point of interest in an image data set captured at illumination level X, where X is a first artificial illumination level, a[x,y] is an intensity as a function of the position (x,y) of an image data point in an image data set of interest captured at illumination level Y, where Y is a second artificial illumination level, and wherein Y is greater than X; andapplying the correction factors to the image data set of interest to obtain an′
illumination corrected image, wherein the correction factors are applied to one or more pixels associated with the non-uniform illumination area of the first image based on the position of a pixel relative to at least one of the representative pixels.
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Specification