Methods and systems for display source light illumination level selection

• US 8,207,932 B2
• Filed: 12/26/2007
• Issued: 06/26/2012
• 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:
  US11/964,674
• Publication Number:
  US 20090167671A1
• Time in Patent Office: 1,644 Days
• Field of Search: 345 76- 83, 345 87-102, 345/63, 345690-692, 358 19- 332, 382/168
• 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 3/3413 Details of control of colour illumination sources

Abstract

Elements of the present invention relate to systems and methods for selecting a display source light illumination level and calculating an image compensation process to compensate for source light illumination level changes.

Claims

1. A method for determining a tonescale adjustment curve parameter, said method comprising:

a) generating an image luminance histogram for an image to be displayed, said luminance histogram comprising bin values;

b) weighting said histogram bin values from said image luminance histogram with distortion weight values, wherein said distortion weight values correspond to a particular source light illumination level, thereby creating weighted histogram values;

c) combining said weighted histogram values to obtain distortion values for each of said source light illumination levels, said distortion values each estimating a sum of respective magnitude errors between each of a plurality of pixels'"'"' displayed values when illuminated at a respectively associated said source light illumination level and said pixels'"'"' displayed values if illuminated by a reference illumination level;

d) selecting a source light illumination level for said image wherein said selecting is based on said distortion values;

e) filtering said selected source light illumination level to determine a filtered source light illumination level;

f) generating a tonescale adjustment curve based on said filtered source light illumination level and a strength factor;

where

g) said magnitude errors are calculated using the following equation;

2. A method as described in claim 1 wherein said selecting is based on a minimum value of said distortion values.

3. A method as described in claim 1 wherein said weighting comprises multiplying said distortion weight values by said histogram bin values.

4. A method as described in claim 1 wherein said combining comprises adding together all weighted histogram values for a given source light illumination level.

5. A method as described in claim 1 further comprising applying said tonescale adjustment curve to said image to create a compensated image.

6. A method as described in claim 1 wherein said generating a tonescale adjustment curve comprises the use of the following equation:

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

a) determining clipping limits for a display model;

b) determining display error vectors based on said clipping limits using the equation;

8. A method as described in claim 7 further comprising filtering said selected source light illumination level to determine a filtered source light illumination level.

9. A method as described in claim 8 further comprising determining a tonescale slope based on said filtered source light illumination level and a strength factor, said tonescale slope defining, in part, a tonescale adjustment curve for a luminance channel of said image.

10. A method as described in claim 7 wherein said determining clipping limits comprises using the following equation:

11. A method as described in claim 7 wherein said weighting said histogram bin values comprises using the following equation:

12. A method as described in claim 7 wherein said determining clipping limits is performed before image processing and said clipping limits are stored for use during processing.

13. A method as described in claim 7 wherein said determining display error vectors is performed before image processing and said display error vectors are stored for use during processing.

14. A method for determining a tonescale adjustment curve parameter, said method comprising:

a) generating an image luminance histogram for an image to be displayed, said luminance histogram comprising bin values;

b) weighting said histogram bin values from said image luminance histogram with distortion weight values, wherein said distortion weight values correspond to a particular source light illumination level, thereby creating weighted histogram values;

c) combining said weighted histogram values to obtain distortion values for each of said source light illumination levels;

d) selecting a source light illumination level for said image wherein said selecting is based on said distortion values;

e) filtering said selected source light illumination level to determine a filtered source light illumination level;

f) generating a tonescale adjustment curve based on said filtered source light illumination level and a strength factor using the equation;

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

a) determining clipping limits for a display model using the equation;

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

a) determining clipping limits for a display model;

b) determining display error vectors based on said clipping limits;

c) generating an image histogram for an image to be displayed, said histogram comprising bin values;

d) weighting said histogram bin values from said image histogram with said display error vectors, wherein said display error vectors correspond to a particular source light illumination level, thereby creating weighted histogram values, and using the equation;