Color Enhancement for Graphic Images

• US 20140270521A1
• Filed: 06/03/2014
• Published: 09/18/2014
• Est. Priority Date: 06/30/2008
• Status: Active Grant

• Current Assignee: Shengqi Yang, Tiehan Lu
• Original Assignee: Shengqi Yang, Tiehan Lu
• Inventors: Yang, Shengqi, Lu, Tiehan
• Granted Patent: US 9,311,696 B2
• Time in Patent Office: Days
• US Class Current: 382/167
• CPC Class Codes: G06T 2207/10016 Video; Image sequence
• CPC Class Codes: G06T 2207/10024 Color image
• CPC Class Codes: G06T 2207/20012 Locally adaptive
• CPC Class Codes: G06T 2207/20182 Noise reduction or smoothing in the temporal domain; Spatio-temporal filtering
• CPC Class Codes: G06T 5/40 using histogram techniques
• CPC Class Codes: G06T 5/90 Dynamic range modification of images or parts thereof
• CPC Class Codes: H04N 1/6027 Correction or control of colour gradation or colour contrast H04N1/6058 takes precedence

Abstract

A color enhancement system may enhance color components in an image. In one embodiment, the color enhancement system suppresses banding by combining an input color value with an enhanced colored value. In another embodiment, local variation in saturation values around a pixel may be used to determine a modification of an input saturation value for color enhancement. As still another embodiment, flickering between frames may be suppressed by combining a histogram that counts the number of times a given pixel value occurs in a particular image with a historical histogram that keeps track of an average of how often given values have occurred in previous frames.

Claims

1. A method of adjusting saturation of an image comprising:

adjusting the saturation of an image based on the variation in saturation values between pixels in the image and the neighbors of those pixels in the same image.

2. The method of claim 1 including using a histogram to keep track of the number of occurrences of saturation values of pixels within an image.

3. The method of claim 2 including changing the number of occurrences of saturation values based on the local variation between a given pixel and its neighbors.

4. The method of claim 3 including blending a historical histogram taken over previous images and a histogram containing the changed number of occurrences of saturation values.

5. The method of claim 4 including using a weighted average of the historical histogram and the histogram containing the changed number of occurrences of saturation values to form a blended histogram.

6. The method of claim 5 including using the blended histogram to modify the saturation values of input pixels.

7. A processing apparatus comprising:

a unit to generate an enhanced saturation value for a plurality of pixels by measuring variation between a saturation value of a pixel and the saturation values of its neighbors in a same image; and

a banding suppression device coupled to said unit and to receive an input saturation value to combine the input saturation value with the enhanced saturation value to create an output saturation value.

8. The apparatus of claim 7, said device to generate a weighted average of the input saturation value and the enhanced saturation value.

9. The apparatus of claim 7 including a device to measure local saturation variance between a pixel and its neighbors.

10. The apparatus of claim 9, said unit to develop a histogram of saturation values encountered within an image.

11. The apparatus of claim 10, said unit to develop a histogram to change the count of saturation values based on the variation between a given pixel and the saturation values of its neighbors.

12. The apparatus of claim 11, said unit to develop a histogram to combine an historical histogram with a histogram for a current image to develop a histogram to modify an input saturation.

13. The apparatus of claim 7 wherein said device is a processor.

14. The apparatus of claim 13 wherein said device is a graphics processor.

15. The apparatus of claim 14, said graphics processor to adjust the saturation of an image based on the variation in saturation values between pixels in the image and the neighbors of those pixels.

16. The apparatus of claim 14, said graphics processor to develop a current histogram of the occurrence of color values of pixels in an image, to maintain an historical histogram that stores the color values of previously analyzed images, and to blend the historical and current histograms.

17. One or more non-transitory computer readable media storing instructions executed by a processor to perform a sequence comprising:

adjusting the saturation of an image based on the variation in saturation values between pixels in the image and the neighbors of those pixels in the same image.

18. The media of claim 17 including using a histogram to keep track of the number of occurrences of saturation values of pixels within an image.

19. The media of claim 18 including changing the number of occurrences of saturation values based on the local variation between a given pixel and its neighbors.

20. The media of claim 19 including blending a historical histogram taken over previous images and a histogram containing the changed number of occurrences of saturation values.

21. The media of claim 20 including using a weighted average of the historical histogram and the histogram containing the changed number of occurrences of saturation values to form a blended histogram.

22. The media of claim 21 including using the blended histogram to modify the saturation values of input pixels.