Image brightness adjusting method
AssigneePrimax Electronics Ltd.
InventorsYing-Jieh Huang, Chiou-Shann Fuh, Hsiang-Ting Chen
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Abstract
An image brightness adjusting method is provided. The brightness values of all pixels of the image are firstly increased in various increasing degrees. Next, the increased brightness values are decreased in various decreasing degrees according to the original brightness values, thereby avoiding over-increasing the brightness values of the image. Moreover, the use of the color saturation values to adjust the brightness values can avoid the unnatural image appearance.
Claims5
An image brightness adjusting method for adjusting brightness values of multiple pixels of an image, all pixels P(x,y) of said image having respective brightness values I(x,y) and respective color saturation values Sat(x,y), said image brightness adjusting method comprising steps of:
- increasing said brightness values I(x,y) of said pixels P(x,y) by a logarithmic function computation, which comprises sub-steps of:
- performing said logarithmic function computation on said brightness values I(x,y) of said pixels P(x,y) to obtain corresponding gain values G(x,y);
- multiplying said brightness values I(x,y) by said gain values G(x,y) to obtain corresponding gained brightness values;
- and amplifying gained brightness values by a magnification S to obtain corresponding brighter brightness values IBrighter(x,y);
- decreasing said brightness values of said image, which comprises sub-steps of:
- decreasing said brightness values I(x,y) of said pixels P(x,y) to obtain corresponding first brightness decay values DBrightness(x,y), wherein said first brightness decay values DBrightness(x,y) are determined according to said brightness values I(x,y) of said pixels P(x,y);
- decreasing said brightness values I(x,y) of said pixels P(x,y) to obtain corresponding second brightness decay value Dsaturation(x,y), wherein said second brightness decay values Dsaturation(x,y) are determined according to corresponding average color saturation values AvgSat(x,y), and each of said average color saturation values AvgSat(x,y) indicates the average of said color saturation values Sat(x,y) of a specified pixel P(x,y) and neighboring pixels thereof;
- and
- obtaining darker brightness values IDarker(X,y) according to said first brightness decay values DBrightness(x,y) and said second brightness decay values Dsaturation(x,y);
- and
- obtaining corrected brightness values IAdjusting(x,y) according to said brighter brightness values IBrighter(x,y) and said darker brightness values IDarker(x,y), wherein said corrected brightness values IAdjusting(x,y) are calculated by following equations:
- IAdjusting(x,y)=IBrighter(x,y)×IDarker(x,y);
- IBrighter(x,y)=S×(1+G(x,y))×I(x,y);
- G(x,y)=log(2−I(x,y));
- IDarker(x,y)=DBrightness(x,y)×Dsaturation(x,y);
- DBrightness(x,y)=1/(1+I(x,y))Power;
- Dsaturation(x,y)=(AvgSat(x,y)+1)/2;
- in which POWER is a power value.
Dependencies are inferred from the claim text.