Method of adaptive image contrast enhancement
DCFirst Claim
Patent Images
1. For an image that includes a plurality of pixels, each pixel having a respective initial luma value and two respective initial chroma values, a method of adjusting the initial luma values, comprising the steps of using a computer to implement the steps of:
- (a) forming a histogram of the initial luma values of at least a portion of the pixels;
(b) computing a plurality of initial bin indices that partitions said histogram into a plurality of bins that have substantially equal populations;
(c) mapping said initial bin indices into a plurality of final bin indices that are spaced more uniformly than said initial bin indices; and
(d) adjusting the initial luma values in accordance with said final bin indices, thereby obtaining, for each pixel, a respective final luma value.
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Abstract
The contrast of a digital image is enhanced by forming a histogram of the luma values of an active area of the image, computing “initial” bin indices that partition the histogram into bins of substantially equal population, mapping the “initial” bin indices into “final” bin indices that are more uniformly spaced than the “initial” bin indices, and adjusting the luma values of all the pixels in accordance with the “final” bin indices.
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Citations
26 Claims
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1. For an image that includes a plurality of pixels, each pixel having a respective initial luma value and two respective initial chroma values, a method of adjusting the initial luma values, comprising the steps of using a computer to implement the steps of:
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(a) forming a histogram of the initial luma values of at least a portion of the pixels; (b) computing a plurality of initial bin indices that partitions said histogram into a plurality of bins that have substantially equal populations; (c) mapping said initial bin indices into a plurality of final bin indices that are spaced more uniformly than said initial bin indices; and (d) adjusting the initial luma values in accordance with said final bin indices, thereby obtaining, for each pixel, a respective final luma value. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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12. For an image that includes a plurality of pixels, each pixel having a respective initial value, a method of adjusting the initial values, comprising the steps of using a computer to implement the steps of:
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(a) forming a histogram of the initial values of at least a portion of the pixels; (b) computing a plurality of initial bin indices that partitions said histogram into a plurality of bins that have substantially equal populations; (c) mapping said initial bin indices into a plurality of final bin indices that are spaced more uniformly than said initial bin indices; and (d) adjusting the initial values in accordance with said final bin indices, thereby obtaining, for each pixel, a respective final value. - View Dependent Claims (13, 14, 15, 16, 17, 18, 19, 20, 21, 22)
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23. A system, comprising:
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(a) a memory for storing an image that includes a plurality of pixels, each pixel having a respective value; and (b) a processor for; (i) forming a histogram of said values of at least a portion of the pixels, (ii) computing a plurality of initial bin indices that partitions said histogram into a plurality of bins that have substantially equal populations, (iii) mapping said initial bin indices into a plurality of final bin indices that are spaced more uniformly than said initial bin indices, and (iv) adjusting said values in accordance with said final bin indices. - View Dependent Claims (24, 25)
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26. A computer readable storage medium having computer readable code embodied on said computer readable storage medium, the computer readable code for enabling a computer to process an image that includes a plurality of pixels, each pixel having a respective value, the computer readable code comprising:
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(a) program code for forming a histogram of the values of at least a portion of the pixels; (b) program code for computing a plurality of initial bin indices that partitions said histogram into a plurality of bins that have substantially equal populations; (c) program code for mapping said initial bin indices into a plurality of final bin indices that are spaced more uniformly than said initial bin indices; and (d) program code for adjusting said values in accordance with said final bin indices.
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Specification