Systems and Methods for Tone Curve Generation, Selection and Application

• US 20070291048A1
• Filed: 08/27/2007
• Published: 12/20/2007
• Est. Priority Date: 12/02/2004
• Status: Active Grant

• Current Assignee: Sharp Kabushiki Kaisha (Hon Hai Precision Industry Co., Ltd.)
• Original Assignee: Sharp Kabushiki Kaisha (Hon Hai Precision Industry Co., Ltd.)
• Inventors: Kerofsky, Louis
• Granted Patent: US 8,120,570 B2
• Time in Patent Office: Days
• US Class Current: 345/589
• CPC Class Codes: G09G 2320/0238 Improving the black level
• 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 2320/066 for control of contrast
• 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 3/3406 Control of illumination source illumination devices structurally associated with liquid crystal cells G02F1/1336

Abstract

Embodiments of the present invention comprise systems and methods for calculating and selecting tone curves for image enhancement.

Claims

1. A method for adjusting image characteristics, said method comprising:

a) determining a performance goal;

b) determining a target tone curve parameter;

c) calculating a set of candidate tone curves based on said target tone curve parameter;

d) selecting one of said set of candidate tone curves based on said performance goal;

e) applying said selected candidate tone curve to said image thereby creating an adjusted image; and

f) displaying said adjusted image.

2. A method as described in claim 1 wherein said performance goal is selected from the set consisting of a lower black level, improved saturation of dark colors, a higher image brightness, improved dynamic contrast, higher intra-frame contrast in a dark frame, and power savings.

3. A method as described in claim 1 wherein said target tone curve parameter is selected from the set consisting of a target display maximum output, a target display contrast ratio and a target display gamma value.

4. A method as described in claim 1 wherein said calculating a set of candidate tone curves comprises calculating candidate tone curves with common parameters, but with varying backlight levels.

5. A method as described in claim 1 wherein said selecting one of said set of candidate tone curves comprises selecting a candidate tone curve corresponding to a backlight level that meets said performance goal.

6. A method as described in claim 1 wherein said selecting one of said set of candidate tone curves comprises selecting a candidate tone curve that meets an image distortion criterion.

7. A method as described in claim 1 further comprising determining a panel tone curve parameter.

8. A method as described in claim 7 further comprising calculating a panel tone curve and a set of candidate tone curves.

9. A method as described in claim 8 wherein said selecting a candidate tone curve comprises comparing said target tone curve to said set of candidate tone curves and selecting the candidate tone curve that results in a minimal error.

10. A method for adjusting image characteristics, said method comprising:

a) determining a target tone curve parameter;

b) determining a panel tone curve

c) calculating a set of candidate tone curves based on said candidate tone curve parameter, wherein said candidate tone curves in said set correspond to different backlight brightness levels;

d) analyzing an image to determine an image characteristic;

e) selecting a selected candidate tone curve from said set of candidate tone curves, wherein said selecting is based on said image characteristic; and

f) applying said selected candidate tone curve to said image thereby creating an adjusted image.

11. A method as described in claim 10 wherein said image characteristic is the dynamic range of said image and said selecting said selected candidate tone curve comprises selecting the candidate tone curve that best fits said dynamic range of said image.

12. A method as described in claim 10 wherein said target tone curve parameter is selected from the set consisting of a target display maximum output, a target display contrast ration and a target display gamma value.

13. A method as described in claim 10 further comprising determining a performance goal and wherein said selecting a selected candidate tone curve is also based on satisfying said performance goal.

14. A method as described in claim 13 wherein said performance goal is selected from the set consisting of a lower black level, improved saturation of dark colors, a higher image brightness, improved dynamic contrast, higher intra-frame contrast in a dark frame, and power savings.

15. A method for adjusting image characteristics, said method comprising:

a) generating a plurality of candidate tone curves, wherein each of said candidate tone curves comprises a black level transition region corresponding to a different backlight brightness level for each candidate tone curve and a common region that is substantially similar in each target tone curve;

b) analyzing an image to determine an image characteristic;

c) selecting a selected candidate tone curve from said plurality of candidate tone curves, wherein said selecting is based on said image characteristic; and

d) applying said selected candidate tone curve to said image thereby creating an adjusted image.

16. A method as described in claim 15 wherein each of said plurality of candidate tone curves also comprises a brightness round-off curve.

17. A method as described in claim 15 wherein said selecting a selected target tone curve is also based on a performance goal.

18. A method as described in claim 15 further comprising generating a panel tone curve and matching said common region of said candidate tone curves to a portion of said panel tone curve.

19. A method as described in claim 15 wherein said image characteristic is an image dynamic range.

20. A method as described in claim 15 further comprising generating a second plurality of enhanced candidate tone curves, wherein each of said enhanced candidate tone curves comprises a black level transition region corresponding to a different backlight brightness level for each enhanced candidate tone curve and an enhanced common region that is substantially similar in each candidate tone curve, but wherein said enhanced common region maps input values to higher output values than said common region;

and wherein said selecting a selected candidate tone curve comprises selecting from said plurality of candidate tone curves and said plurality of enhanced candidate tone curves.