Contrast control device and method therefor

• US 8,599,318 B2
• Filed: 05/21/2010
• Issued: 12/03/2013
• Est. Priority Date: 05/21/2010
• Status: Active Grant

• Current Assignee: VIXS Systems Incorporated (Pixelworks Incorporated)
• Original Assignee: VIXS Systems Incorporated (Pixelworks Incorporated)
• Inventors: Astrachan, Paul M., Aardema, Chris A.
• Primary Examiner(s): YENKE, BRIAN P
• Application Number:
  US12/784,793
• Publication Number:
  US 20110285911A1
• Time in Patent Office: 1,292 Days
• Field of Search: 348/607, 348/620, 348/659, 348/672, 348/687
• US Class Current: 348/672
• CPC Class Codes: H04N 21/4318 by altering the content in the rendering process, e.g. blanking, blurring or masking an image region image enhancement or restoration in general G06T5/00
• CPC Class Codes: H04N 21/44008 involving operations for analysing video streams, e.g. detecting features or characteristics in the video stream arrangements characterised by components specially adapted for monitoring, identification or recognition of video in broadcast systems H04H60/59
• CPC Class Codes: H04N 5/57 Control of contrast or brightness

Abstract

A first video picture is translated based upon a first translation matrix to adjust a contrast of the first video image. A second translation matrix is determined based upon a first histogram of a second video picture. A third translation matrix is determined based upon the first translation matrix and the second translation matrix, and the video picture is translated based upon the third translation matrix. The translation matrix can be determined using a histogram that has been adjusted using a clipped histogram equalization technique.

Claims

1. A method comprising:

at a video processor, determining a first histogram based upon a first video picture, the first histogram comprising a plurality of bins including a first bin and a second bin;

determining for a first clip line of the first histogram a first total number of clipped points that includes a number of points of the first bin clipped by the first clip line and a number of points of the second bin clipped by the first clip line;

determining for a second clip line of the first histogram a second total number of clipped points that includes a number of pixels of the first bin clipped by the second clip line and a number of points of the second bin clipped by the second clip line, wherein determining the first total number and the second total number occurs concurrently;

determining a first translation matrix based upon the first histogram of the first video picture; and

translating a second video picture based upon the first translation matrix.

2. The method of claim 1 wherein the first translation matrix is further based upon a second translation matrix that was generated prior to the second translation matrix.

3. The method of claim 2, wherein the second translation matrix is based upon a statistical calculation based upon a plurality of translation matrices.

4. The method of claim 3, wherein the statistical calculation is a moving average based upon the plurality of translation matrices.

5. The method of claim 1, wherein determining the first translation matrix includes:

determining a final clip line of the histogram based upon a number of points of the first histogram determined to be clipped by one of the first clip line or the second clip line.

6. The method of claim 5 further comprising:

determining the first and second clip lines based upon a number of histogram points of the first histogram to be redistributed.

7. The method of claim 6, wherein the number of histogram points to be redistributed is based upon a predefined percentage of the total number of points of the histogram.

8. The method of claim 7, wherein the predefined percentage is user programmable.

9. The method of claim 7, wherein the predefined percentage is a predefined variable percentage.

10. The method of claim 6, wherein determining the first and second clip lines includes determining a plurality of clip lines, including the first and second clip lines, based upon the number points of the first of histogram to be redistributed and the number of bins in the histogram.

11. The method of claim 6, wherein the first and second clip lines are adjacent clip lines of a plurality of clip lines, and a spacing between the first and second clip lines is based upon the number of histogram points to be redistributed divided by the number of bins in the histogram.

12. The method of claim 6, wherein the first and second clip lines are adjacent clip lines of a plurality of clip lines, and a spacing between adjacent clip lines of the plurality of clip lines is non-linear.

13. The method of claim 5, wherein the first clip line is a clip line above which too few points have been clipped, and determining the final clip line includes:

concurrently determining at the integrated circuit a number of points of the first and second bin clipped by a third clip line and a fourth clip line, the third and fourth clip lines determined based upon a number of points clipped by the first clip line.

14. A video processing device comprising:

a storage location to store a first translation matrix based upon a first video picture;

a translation matrix generation module to determine a second translation matrix based upon a histogram of a second video picture, the translation module comprising a plurality of clip count modules including a first clip count module and a second count module;

the first clip count module to determine a number of points of a first bin of the histogram clipped by a first clip line, and a number of points of a second bin of the histogram clipped by the first clip line;

the second clip count module to determine a number of points of the first bin clipped by a second clip line, and a number of points of the second bin clipped by the first clip line;

a statistical calculation module to determine a third translation matrix based upon a statistical calculation that includes the first translation matrix and the second translation matrix; and

a picture translation module to translate the first video picture based upon the first translation matrix, and to translate the second video picture based upon the third translation matrix.

15. The device of claim 14, wherein the translation matrix generation module is to further determine a fourth translation matrix based upon a third video picture, and the statistical calculation module is further to determine a fifth translation matrix based upon the statistical calculation that includes the third translation matrix and the fourth translation matrix, and picture translation module to translate the third video picture based upon the fifth translation matrix.

16. The device of claim 14 further comprising:

a memory to store the histogram; and

a memory controller to read and provide the histogram information to each clipping module in response to reading the histogram information from the memory a single time.

17. A method comprising:

generating, at a first video processor, a first histogram based solely on a first video picture;

identifying a first plurality of clip lines for the first histogram;

concurrently determining, at the video processor device, a number of histogram points at a set of bins of the first histogram that are clipped by each clip line of the plurality of clip lines, wherein each clip line is applied to each bin of the set of bins, and wherein the number of histogram points clipped by each clip line is based upon the total number of points of the first histogram above that clip line;

determining, at the video processor device, a final clip line of the histogram based upon a number of points of the histogram determined to be clipped by a first clip line of the plurality of clip lines, wherein the final clip line is not one of the first plurality of clip lines; and

determining a translation matrix based upon the final clip line and the first histogram.

18. The method of claim 17 further comprising:

redistributing a plurality of histogram points clipped by the final clip line to define a second histogram.

19. The method of claim 17, further including:

determining the plurality of clip lines based upon a number of first histogram points to be redistributed.

20. A method comprising:

translating a first video picture based upon a first translation matrix;

determining a plurality of clip lines based upon a number of histogram points of a first histogram to be redistributed and the number of bins in the first histogram;

concurrently determining at an integrated circuit a number of points of the first histogram clipped by each clip line of a plurality of clip lines;

determining a final clip line of the histogram based upon a number of points of the first histogram determined to be clipped by a first clip line of the plurality of clip lines;

determining a second translation matrix based upon the first histogram of a second video picture;

determining a third translation matrix based upon the first translation matrix and the second translation matrix; and

translating the second video picture based upon the third translation matrix.

21. A method comprising:

translating a first video picture based upon a first translation matrix;

determining a plurality of clip lines based upon a number of histogram points of a first histogram to be redistributed, wherein the spacing between adjacent clip lines of the plurality of clip lines is based upon the number of points of the histogram points to be redistributed divided by the number of bins in the histogram;

concurrently determining at an integrated circuit a number of points of the first histogram clipped by each clip line of a plurality of clip lines;

determining a final clip line of the histogram based upon a number of points of the first histogram determined to be clipped by a first clip line of the plurality of clip lines;

determining a second translation matrix based upon the first histogram of a second video picture;

determining a third translation matrix based upon the first translation matrix and the second translation matrix; and

translating the second video picture based upon the third translation matrix.

22. A method comprising:

translating a first video picture based upon a first translation matrix;

concurrently determining at an integrated circuit a number of points of the first histogram clipped by each clip line of a plurality of clip lines;

determining a final clip line of the histogram based upon a number of points of the first histogram determined to be clipped by a first clip line of the plurality of clip lines, wherein the plurality of clip lines is a first plurality of clip lines, the first clip line is a clip line above which too few points have been clipped, and determining the final clip line includes;

concurrently determining at the integrated circuit a number of points of the first histogram clipped by each clip line of a second plurality of clip lines, the second plurality of bit lines determined based upon a number of points clipped by the first clip line; and

determining the final clip line of the histogram is further based upon a number of points of the first histogram determined to be clipped by a second clip line of the second plurality of clip lines

determining a second translation matrix based upon the first histogram of a second video picture;

determining a third translation matrix based upon the first translation matrix and the second translation matrix; and

translating the second video picture based upon the third translation matrix.