Color management unit

• US 7,746,411 B1
• Filed: 12/07/2005
• Issued: 06/29/2010
• Est. Priority Date: 12/07/2005
• Status: Active Grant

• Current Assignee: Synaptics Incorporated, Synaptics, LLC (Synaptics Incorporated)
• Original Assignee: Marvell International Limited (Marvell Technology Group Limited)
• Inventors: Srinivasan, Sujith, Balram, Nikhil, Garg, Sanjay, Ghosh, Bipasha
• Primary Examiner(s): Yenke; Brian P
• Application Number:
  US11/296,185
• Time in Patent Office: 1,665 Days
• Field of Search: 348/649, 348/656, 348/657, 348/661, 348/672, 348/674, 348/678, 348/687, 345/589, 345/603, 345/604, 358/520, 382/167, 382/169
• US Class Current: 348/649
• CPC Class Codes: H04N 9/643 Hue control means, e.g. flesh tone control
• CPC Class Codes: H04N 9/67 for matrixing camera processing pipelines for matrixing of colour signals H04N23/85
• CPC Class Codes: H04N 9/68 for controlling the amplitude of colour signals, e.g. automatic chroma control circuits H04N9/71, H04N9/73 take precedence; camera processing pipelines for controlling the colour saturation of colour signals H04N23/86

Abstract

A color management unit is architected to achieve higher-quality appearance used in various video formats and to enable improvements in picture contrast and colorfulness. The color management unit comprises an optional input color space converter to convert the input digital video to a desired color space, an adaptive contrast enhancer to apply contrast improvement algorithms in response to different scenes in either manual or automatic modes, intelligent color remapping for enhancing selected colors, sRGB compliance to produce a video display that is uniform over different monitors, global color and brightness controls to combine global processing and color conversion, gamut compression to maintain pixel validity in color space conversion, and gamma correction to compensate for nonlinear characteristics of an output display.

Claims

1. A method for processing a video signal, comprising:

calculating a weighting factor independently for each of a plurality of regions based on a mean value and an approximate variance of each of the plurality of regions;

equalizing each of the plurality of regions of luminance values in the video signal, based on the independently calculated weighting factors, to produce a contrast enhanced video signal using an adaptive contrast enhancer circuitry;

remapping the video signal to produce a color enhanced video signal wherein selected colors of the video signal are enhanced using intelligent color remapper circuitry; and

display adapting the contrast enhanced video signal and the color enhanced video signal to produce a video signal output, wherein the video signal output is produced in accordance with characteristics of a particular display, whereby the processed video signal appears to be the same when viewed across different displays.

2. The method of claim 1, further comprising converting pixels of the video signal from RGB coordinates to YUV coordinates.

3. The method of claim 1, wherein colors of the color enhanced video signal are remapped in response to linear interpolation of neighboring axes on a color wheel.

4. The method of claim 1, wherein colors of the color enhanced video signal are remapped in response to flesh tone, hue, and saturation parameters.

5. The method of claim 4, further comprising converting the video signal output from YUV coordinates to RGB coordinates.

6. The method of claim 5, further comprising desaturating the converted video signal output to fall within a valid range for an RGB display.

7. The method of claim 6, further comprising gamma compensating the desaturated converted video signal output to compensate for nonlinear characteristics of output displays.

8. The method of claim 1, further comprising implementing the contrast enhancement, remapping, and display adapting using a monolithic integrated circuit.

9. A system for processing a video signal, comprising:

an adaptive contrast enhancer that is configured to;

calculate a weighting factor independently for each of a plurality of regions based on a mean value and an approximate variance of each of the plurality of regions, and

equalize each of the plurality of regions of luminance values, based on the independently calculated weighting factors;

an intelligent color remapper that is configured to enhancing selected colors of the video signal; and

an sRGB compliance unit that is configured to receive video signal output of the adaptive contrast enhancer and the intelligent color remapper, and to process the video signal output such that the processed video signal output in accordance with characteristics of a particular display, whereby the processed video signal appears to be the same when viewed across different displays.

10. The system of claim 9, further comprising a color space converter that is configured to convert pixels of the video stream from RGB coordinates to YUV coordinates.

11. The system of claim 9, wherein the intelligent color remapper is configured to map colors in response to linear interpolation of neighboring axes on a color wheel.

12. The system of claim 9, wherein the intelligent color remapper comprises flesh tone, hue, and saturation processors.

13. The system of claim 9, wherein the sRGB compliance unit comprises a YUV to RGB converter for converting the processed video signal output.

14. The system of claim 13, further comprising a gamut compression block that is configured to desaturate the converted processed video signal output to fall within a valid range for an RGB display.

15. The system of claim 14, further comprising a gamma correction unit that is configured to gamma compensate the desaturated converted processed video signal output to compensate for nonlinear characteristics of output displays.

16. The system of claim 9, wherein the system is implemented on an integrated circuit.

17. A system for processing a video signal, comprising:

means for calculating a weighting factor independently for each of a plurality of regions based on a mean value and an approximate variance of each of the plurality of regions;

means for equalizing each of the plurality of regions of luminance values in the video signal, based on the independently calculated weighting factors, to produce a contrast enhanced video signal;

means for remapping the video signal to produce a color enhanced video signal wherein selected colors of the video signal are enhanced; and

means for display adapting the contrast enhanced video signal and the color enhanced video signal to produce a video signal output, wherein the video signal output is produced in accordance with characteristics of a particular display, whereby the processed video signal appears to be the same when viewed across different displays.

18. The system of claim 17, further comprising means for converting pixels of the video stream from RGB coordinates to YUV coordinates.

19. The system of claim 17, wherein the means for remapping the video signal remaps colors in response to linear interpolation of neighboring axes on a color wheel.

20. The system of claim 17, further comprising means for processing flesh tone, hue, and saturation of the video signal output.