ADAPTIVE CONTRAST ENHANCEMENT APPARATUS AND METHOD
First Claim
1. An adaptive contrast enhancement method, comprising:
- calculating a probability density function based on pixel values of a plurality of pixels of an input image signal;
dividing the plurality of pixels into one of a plurality of low-brightness sets and high-brightness sets according to the pixel values of the plurality of pixels, wherein a part of the plurality of pixels with pixel values below one of a plurality of delimiting values are allocated to the low-brightness set and a part of the plurality of pixels with pixel values above the delimiting value are allocated to the high-brightness set;
determining a mapping function according to the probability of the plurality of pixels in the low-brightness set and the probability of the plurality of pixels in the high-brightness set; and
mapping the input image signal to an output image signal according to the mapping function.
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Abstract
An adaptive contrast enhancement method, the steps include: calculating a probability density function based on pixel values of a plurality of pixels of an input image signal; dividing the plurality of pixels into one of a plurality of low-brightness sets and high-brightness sets according to the pixel values of the plurality of pixels, wherein a part of the plurality of pixels with pixel values below one of a plurality of delimiting values are allocated to the low-brightness set and a part of the plurality of pixels with pixel values above the delimiting value are allocated to the high-brightness set; determining a mapping function according to the probability of the plurality of pixels in the low-brightness set and the probability of the plurality of pixels in the high-brightness set; and mapping the input image signal to an output image signal according to the mapping function.
10 Citations
16 Claims
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1. An adaptive contrast enhancement method, comprising:
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calculating a probability density function based on pixel values of a plurality of pixels of an input image signal; dividing the plurality of pixels into one of a plurality of low-brightness sets and high-brightness sets according to the pixel values of the plurality of pixels, wherein a part of the plurality of pixels with pixel values below one of a plurality of delimiting values are allocated to the low-brightness set and a part of the plurality of pixels with pixel values above the delimiting value are allocated to the high-brightness set; determining a mapping function according to the probability of the plurality of pixels in the low-brightness set and the probability of the plurality of pixels in the high-brightness set; and mapping the input image signal to an output image signal according to the mapping function. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. An adaptive contrast enhancement apparatus, comprising:
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a probability density function and cumulative distribution function calculator, calculating a probability density function based on pixel values of a plurality of pixels of an input image signal; a mapping function calculator, dividing the plurality of pixels into one of a plurality of low-brightness sets and high-brightness sets according to the pixel values of the plurality of pixels and determining a mapping function according to the probability of the plurality of pixels in the low-brightness set and the probability of the plurality of pixels in the high-brightness set, wherein a part of the plurality of pixels with pixel values below one of a plurality of delimiting values are allocated to the low-brightness set and a part of the plurality of pixels with pixel values above the delimiting value are allocated to the high-brightness set; and a mapper, mapping the input image signal to an output image signal according to the mapping function. - View Dependent Claims (10, 11, 12, 13, 14, 15, 16)
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Specification