Methods and systems for display source light management with histogram manipulation

• US 8,179,363 B2
• Filed: 12/26/2007
• Issued: 05/15/2012
• Est. Priority Date: 12/26/2007
• Status: Active Grant

• Current Assignee: Sharp Kabushiki Kaisha (Hon Hai Precision Industry Co., Ltd.)
• Original Assignee: Sharp Laboratories of America Incorporated (Hon Hai Precision Industry Co., Ltd.)
• Inventors: Kerofsky, Louis J.
• Primary Examiner(s): Lao, Lun-Yi
• Assistant Examiner(s): Abebe, Sosina
• Application Number:
  US11/964,689
• Publication Number:
  US 20090167672A1
• Time in Patent Office: 1,602 Days
• Field of Search: 345 76- 83, 345 87-102, 345/214, 345/589, 345/690, 362 971- 973
• US Class Current: 345/102
• CPC Class Codes: G09G 2320/0271 Adjustment of the gradation levels within the range of the gradation scale, e.g. by redistribution or clipping
• CPC Class Codes: G09G 2320/0646 Modulation of illumination source brightness and image signal correlated to each other
• CPC Class Codes: G09G 2320/0653 Controlling or limiting the speed of brightness adjustment of the illumination source
• CPC Class Codes: G09G 2320/0673 for control of gamma adjustment, e.g. selecting another gamma curve
• CPC Class Codes: G09G 2330/021 Power management, e.g. power saving
• CPC Class Codes: G09G 2360/144 the light being ambient light
• CPC Class Codes: G09G 2360/16 Calculation or use of calculated indices related to luminance levels in display data
• CPC Class Codes: G09G 3/2003 Display of colours specific for liquid crystal displays G09G3/3607
• CPC Class Codes: G09G 3/3413 Details of control of colour illumination sources

Abstract

Elements of the present invention relate to systems and methods for generating, converting and using histograms in an image processing system. Aspects of some embodiments also relate to generation of a one-dimensional histogram based on luminance and compound color channel data. Some embodiments also relate to histogram dynamic range conversion.

Claims

1. A method for creating a one-dimensional histogram for a color image, said method comprising:

a) calculating a luminance channel from three-color-channel image data for an input image;

b) calculating a compound color channel from said three-color-channel image data;

c) generating a two-dimensional histogram from said luminance channel and said compound color channel; and

d) summing histogram values of said two-dimensional histogram along diagonal summation lines to convert said two-dimensional histogram to a one-dimensional histogram.

2. A method as described in claim 1 further comprising reading a color weight parameter that defines a slope of said summation lines.

3. A method as described in claim 1 wherein said compound color channel is a color difference channel.

4. A method as described in claim 1 wherein said luminance channel is calculated with the following equation:

Y=0.29R+0.59G+0.12B.

5. A method as described in claim 3 wherein said color difference channel is calculated using the following equation:

C=max(R−

Y,G−

Y,B−

Y).

6. A method as described in claim 1 further comprising changing the dynamic range of said one-dimensional histogram using linear scaling.

7. A method as described in claim 1 further comprising weighting said one-dimensional histogram with an error vector to obtain a performance metric, where said error vector reflects respective magnitudes by which the actual illumination level of each of a plurality of image pixels illuminated at an image code value illumination level varies from said image code value illumination level.

8. A method for selecting a display source light illumination level, said method comprising:

a) calculating a luminance channel from three-color-channel image data for an input image;

b) calculating a compound color channel from said three-color-channel image data;

c) generating a two-dimensional histogram from said luminance channel and said compound color channel;

d) summing histogram values of said two-dimensional histogram along diagonal summation lines to convert said two-dimensional histogram to a one-dimensional histogram;

e) using said one-dimensional histogram to create a display model;

f) generating an error vector with said display model;

g) weighting said one-dimensional histogram with said error vector;

h) determining a performance metric with said weighted one-dimensional histogram; and

i) selecting a source light illumination level based on said performance metric.

9. A method as described in claim 8 further comprising reading a color weight parameter that defines a slope of said summation lines.

10. A method as described in claim 8 wherein said compound color channel is a color difference channel.

11. A method as described in claim 8 wherein said luminance channel is calculated with the following equation:

Y=0.29R+0.59G+0.12B.

12. A method as described in claim 10 wherein said color difference channel is calculated using the following equation:

C=max(R−

Y,G−

Y,B−

Y).

13. A method as described in claim 8 further comprising changing the dynamic range of said one-dimensional histogram using linear scaling.

14. A method as described in claim 8 further comprising weighting said one-dimensional histogram with an error vector to obtain a performance metric.

15. A method as described in claim 8 wherein said generating an error vector comprises determining model clipping limits.

16. A method as described in claim 8 further comprising generating an image tonescale correction curve based on said selected source light illumination level.

17. A method for selecting a display source light illumination level, said method comprising:

a) generating a two-dimensional histogram from a luminance channel and a compound color channel;

b) summing histogram values of said two-dimensional histogram along diagonal summation lines to convert said two-dimensional histogram to a one-dimensional histogram;

c) receiving said one-dimensional histogram at a mapping module comprising a map that associates an image characteristic to a display model attribute;

d) determining an image characteristic based on said one-dimensional histogram;

e) determining a display model attribute that is associated with said image characteristic using said map and said mapping module;

f) generating a display model based on said display model attribute;

g) calculating model clipping limits for said display model;

h) calculating a display error vector that reflects respective magnitudes by which the actual illumination level of each of a plurality of image pixels illuminated at an image code value illumination level varies from said image code value illumination level, and for each of a plurality of source light illumination levels;

i) combining said display error vectors with said one-dimensional histogram to determine a distortion value for said plurality of source light illumination levels; and

j) selecting a source light illumination level based on said distortion values.

18. A method as described in claim 17 further comprising reading a color weight parameter that defines a slope of said summation lines.

19. A method as described in claim 17 wherein said compound color channel is a color difference channel.

20. A method as described in claim 17 further comprising changing the dynamic range of said one-dimensional histogram using linear scaling.