Method for processing a backlight image and device thereof
A method for processing an image includes inputting an image, generating a first mean luminance value and a second mean luminance value according to a plurality of pixels within a first luminance interval and a second luminance interval of the image, generating a first luminance threshold according to the first mean luminance value, setting a compensation parameter, generating a first compensation luminance value according to the first mean luminance value and the compensation parameter, generating a second compensation luminance value according to the first luminance threshold, the first mean luminance value, the second mean luminance value, and the compensation parameter, and adjusting luminance values of pixels within the a smaller compensation luminance value and a greater compensation luminance value according to the smaller compensation value and a comparison between the first compensation luminance value and the second compensation luminance value.
1. An image processing method comprising:
(a) inputting image data comprising a plurality of pixels;
(b) setting a first luminance interval and a second luminance interval;
(c) generating a first mean luminance value from a plurality of pixels of the image data within the first luminance interval;
(d) generating a second mean luminance value from a plurality of pixels of the image data within the second luminance interval;
(e) generating a first luminance threshold according to the first mean luminance value;
(f) setting a compensation parameter;
(g) generating a first compensation luminance value according to the first mean luminance value and the compensation parameter;
(h) generating a second compensation luminance value according to the first luminance threshold, the first mean luminance value, the second mean luminance value and the compensation parameter;
(i) obtaining a greater compensation luminance value according to a comparison between the first and second compensation luminance values; and
(j) adjusting luminance values of image data between a smaller compensation luminance value and the greater compensation luminance value according to the smaller and greater compensation luminance values.
2. The method of claim 1 further comprising checking if the image data is backlight image data.
3. The method of claim 2 , wherein checking if the image data is backlight image data comprises determining the image data is backlight image data when a ratio of the number of pixels within the first luminance interval to the number of pixels within the image data, and a ratio of the number of pixels within the second luminance interval to the number of pixels within the image data are greater than a specific ratio respectively.
4. The method of claim 2 , wherein checking if the image data is backlight image data comprises determining the image data is backlight image data when a sum of a ratio of the number of pixels within the first luminance interval to the number of pixels of the image data and a ratio of the number of pixels within the second luminance interval to the number of pixels within the image data is greater than a specific ratio.
5. The method of claim 1 , wherein step (c) comprises generating the corresponding first mean luminance value according to half an accumulated number corresponding to luminance values within the first luminance interval, the accumulated number being accumulated from a number corresponding to the smallest luminance value to a number corresponding to the greatest luminance within the first luminance interval.
6. The method of claim 1 , wherein step (c) comprises generating the first mean luminance value according to a weighted average of the luminance values and the number corresponding to the luminance values within the first luminance interval.
7. The method of claim 1 , wherein step (d) comprises generating the corresponding second mean luminance value according to half an accumulated number corresponding to luminance values within the second luminance interval, the accumulated number being accumulated from a number corresponding to the smallest luminance value to a number corresponding to the greatest luminance within the second luminance interval.
8. The method of claim 1 , wherein step (c) comprises generating the second mean luminance value according to a weighted average of the luminance values and the number corresponding to the luminance values within the second luminance interval.
9. The method of claim 1 , wherein the first compensation luminance value in step (g) is a sum of the first mean luminance value and the compensation parameter.
10. The method of claim 1 , wherein step (f) comprises generating the compensation parameter according to the first mean luminance value and the second mean luminance value.
11. The method of claim 10 , wherein the compensation parameter is (the first mean luminance value+the second mean luminance value)/(a positive integer).
12. The method of claim 10 , wherein the positive integer is 2.
13. The method of claim 1 , wherein the second compensation luminance value in step (h) is (the first luminance threshold)+|the second mean luminance value−the first luminance threshold|/(the second luminance threshold−the first mean luminance value)*(the compensation parameter).
14. The method of claim 13 , wherein the compensation parameter is (the first mean luminance value+the second mean luminance value)/2.
15. The method of claim 1 , wherein the greater compensation luminance value is a greater value between the first compensation luminance value and the second compensation luminance value.
16. The method of claim 1 further comprising providing a value γ, and generating the adjusted luminance in step (j) through a following equation:
the adjusted luminance value=the greater compensation luminance value−(the greater compensation luminance value−the unadjusted luminance value) γ /(the greater compensation luminance value−the smaller compensation luminance value) (γ-1) .
17. The method of claim 16 , wherein the value γ is greater than 1.
18. The method of claim 1 further comprising not adjusting the luminance values of image data outside the range between the smaller and the greater compensation luminance values.
19. An image processing system comprising:
an image inputting module for inputting image data;
a mean luminance value calculating device for generating a first mean luminance value according to a plurality of pixels within a first luminance interval of the image data, and generating a second mean luminance value according to a plurality of pixels within a second luminance interval of the image data;
a compensation luminance value calculating device for generating a first compensation luminance value according to the first mean luminance value and a compensation parameter, and generating a second compensation luminance value according to a first luminance threshold, the first mean luminance value, the second mean luminance value, and the compensation parameter;
a compensation luminance value comparing device for generating a greater compensation luminance value according to a comparison between the first and second compensation luminance values; and
a processing device for adjusting luminance values of image data between a smaller compensation luminance value and the greater compensation luminance value according to the smaller and greater compensation luminance values.
20. The image processing system of claim 19 further comprising a determining device for determining if the image data is a backlight image.