Methods and systems for enhancing display characteristics with frequency-specific gain

• US 20060284823A1
• Filed: 06/15/2005
• Published: 12/21/2006
• Est. Priority Date: 06/15/2005
• 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 Joseph, Daly, Scott James
• Granted Patent: US 8,913,089 B2
• Time in Patent Office: Days
• 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 2320/0276 for the purpose of adaptation to the characteristics of a display device, i.e. gamma correction
• CPC Class Codes: G09G 2320/0646 Modulation of illumination source brightness and image signal correlated to each other
• CPC Class Codes: G09G 2330/021 Power management, e.g. power saving
• CPC Class Codes: G09G 2360/16 Calculation or use of calculated indices related to luminance levels in display data
• 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, methods and devices for increasing the perceived brightness of an image. In some embodiments this increase compensates for a decrease in display light source illumination.

Claims

1. A method for adjusting an image for increased brightness, said method comprising:

a) applying a tone scale adjustment model to a low-pass (LP) version of an image to form an adjusted LP image;

b) applying a constant gain factor to a high-pass (BP) version of said image to form an adjusted HP image;

c) adding said adjusted LP image to said adjusted HP image to form a brightness-enhanced image.

2. A method as described in claim 1 wherein said applying a tone scale adjustment model comprises applying a constant gain multiplier to a first range of code values and applying a roll-off curve to a second range of code values.

3. A method as described in claim 1 wherein said applying a tone scale adjustment model comprises applying a gain adjustment to a range of code values below maximum value point (MFP) and applying a roll-off curve to code values above said MFP.

4. A method as described in claim 3 wherein said roll-off curve begins at the value of said gain map function at said MFP and ends at a point that maps the maximum code value to the maximum display level.

5. A method as described in claim 3 wherein said roll-off curve matches the slope of said gain adjustment at said MFP point.

6. A method as described in claim 1 wherein said applying a tone scale adjustment model comprises adjusting the code values of a first group of image pixels to increase the perceived brightness of said pixels by applying a gain factor function;

and adjusting the code values of a second group of image pixels according to a transition function that transitions from said gain factor function to no gain at a maximum value point.

7. A method as described in claim 1 wherein said gain function is related to the slope of the tone scale adjustment model.

8. A method as described in claim 1 wherein said gain function is proportional to the ratio of the slope of the tone scale adjustment model at a point below an MFP and the slope of the tone scale adjustment model at a specific code value.

9. A method as described in claim 1 wherein said gain function is proportional to the ratio of the slope of the tone scale adjustment model at a point below an FTP and the slope of the tone scale adjustment model at a specific code value.

10. A method for adjusting an image for increased brightness, said method comprising:

a) applying a low-pass (LP) filter to an image to create an LP version of said image;

b) subtracting said LP version of said image from said image to create a high-pass (HP) version of said image;

c) applying a tone scale adjustment model to said LP version of said image to form an adjusted LP image;

d) applying a constant gain factor to said HP version of said image to form an adjusted HP image;

e) adding said adjusted LP image to said adjusted HP image to form a brightness enhanced image.

11. A method as described in claim 10 wherein said applying a tone scale adjustment model comprises adjusting the code values of a first group of image pixels to increase the perceived brightness of said pixels by applying a gain factor function;

and adjusting the code values of a second group of image pixels according to a transition function that transitions from said gain factor function to no gain at a maximum value point.

12. A method as described in claim 10 wherein said computing a high-pass image comprises low pass filter said tone scale adjusted image to produce a low-pass image and subtracting said low-pass image from said tone scale adjusted image to produce said high-pass image.

13. A method as described in claim 10 wherein said gain function is related to the slope of the tone scale adjustment model.

14. A method as described in claim 10 wherein said gain function is proportional to the ratio of the slope of the tone scale adjustment model below an MFP and the slope of the tone scale adjustment model at a specific code value.

15. A method as described in claim 10 wherein said gain function is proportional to the ratio of the slope of the tone scale adjustment model below an FTP and the slope of the tone scale adjustment model at a specific code value.

16. An apparatus for adjusting an image for increased brightness, said apparatus comprising:

a) a low-pass (LP) filter for fling an image and creating a LP version of said image;

b) a tone scale adjustment model for adjusting said LP version of said image thereby creating an adjusted LP image;

c) a processor for subtracting said LP version of said image from said image to create a HP version of said image;

d) a second processor for applying a constant gain factor to said high-pass (HP) version of said image to form an adjusted HP image;

e) an adder for adding said adjusted LP image to said adjusted HP image to form a brightness-enhanced image.

17. A method as described in claim 16 wherein said applying a tone scale adjustment model comprises applying a constant gain multiplier to a first range of code values and applying a roll-off curve to a second range of code values.

18. A method as described in claim 16 wherein said applying a tone scale adjustment model comprises applying a gain adjustment to a range of code values below an MFP point and applying a roll-off curve to code values above said MFP point.

19. A method as described in claim 16 wherein said roll-off curve begins at the value of said gain map function at said MFP and ends at a point that maps the maximum code value to the maximum display level.

20. An apparatus as described in claim 16 wherein said applying a tone scale adjustment model comprises adjusting the code values of a first group of image pixels to increase the perceived brightness of said pixels by applying a gain factor function;

and adjusting the code values of a second group of image pixels according to a transition function that transitions from said gain factor function to no gain at a maximum value point.