Patent ID: 8154663

Claim:
A method for contrast enhancement of a video signal, comprising: receiving a video signal frame of the video signal; gathering statistics about the video signal frame; calculating the effective input dynamic range of the video signal frame; calculating the effective output dynamic range of the video signal frame; and constructing a transform to enhance the picture in the video signal frame by mapping the effective input dynamic range to the effective output dynamic range via the transform; wherein the effective output dynamic range is calculated in one of the following ways: L i ′=MEAN i −k *(MEAN i −L i ), H i ′=MEAN i +k *( H i −MEAN i ), i) where [L i ,H i ] is the effective input dynamic range, [L i ′,H i ′] is the effective output dynamic range, MEAN i is the mean value of luma, and k is an enhancement factor; L i ′=MED i −k *(MED i −L i ), H i ′=MED i +k *( H i −MED i ), ii) where [L i ,H i ] is the effective input dynamic range, [L i ′,H i ′] is the effective output dynamic range, MED i is the median of luma values of the received video frame, and k is an enhancement factor; iii) H i ′ - MEAN i MEAN i - L i ′ = H i - MEAN i MEAN i - L i , where [L i ,H i ] is the effective input dynamic range, [L i ′,H i ′] is the effective output dynamic range, and MEAN i is the mean value of luma; or iv) H i ′ - MED i MED i - L i ′ = H i - MED i MED i - L i , where [L i ,H i ] is the effective input dynamic range, [L i ′,H i ′] is the effective output dynamic range, and MED i is the median of luma values of the received video signal frame.