Methods and systems for image-specific tone scale adjustment and light-source control

• US 7,961,199 B2
• Filed: 09/12/2005
• Issued: 06/14/2011
• Est. Priority Date: 12/02/2004
• Status: Expired due to Fees

• 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: Sugino, Michiyuki, Kerofsky, Louis Joseph, Daly, Scott J.
• Primary Examiner(s): Johnson; M Good
• Application Number:
  US11/224,792
• Publication Number:
  US 20060119612A1
• Time in Patent Office: 2,101 Days
• Field of Search: 345/426, 345/590
• US Class Current: 345/590
• CPC Class Codes: G09G 2320/02 Improving the quality of display appearance
• 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 2320/0626 for control of overall brightness
• CPC Class Codes: G09G 2320/0633 by amplitude modulation of the brightness of the illumination source
• 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 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 3/22 using controlled light sources
• 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 adjusting image code values in conjunction with display light source illumination levels for enhanced image display.

Claims

1. A method for displaying an image, said method comprising:

a) analyzing said image, with a computing device, to determine an adjusted display source light illumination level;

b) using said adjusted display source light illumination level to determine a tone scale adjustment model that is dependent on said source light illumination level, wherein application of said tone scale adjustment model to said image adjusts pixel code values in said image thereby creating a tone scale adjusted image such that display of said tone scale adjusted image using said adjusted display source light illumination level produces similar output as said pixel code values would produce when displaying said image using a full source light illumination level;

c) applying said tone scale adjustment model to said image to produce a tone scale adjusted image; and

d) displaying said adjusted image on a display using said adjusted display source light illumination level, wherein said adjusted display source light illumination level is used to control a display source light for all color channels of a display during said displaying.

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 a maximum fidelity point (MFP) and applying a roll-off curve to code values above said MFP.

4. A method as described in claim 1 wherein said tone scale adjustment model is dependent on at least one of a display gamma, an efficiency factor and a maximum fidelity point (MFP).

5. 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.

6. A method for adjusting an image in coordination with a display source light level, said method comprising:

a) analyzing said image, with a computing device, to determine an adjusted display source light illumination level;

b) analyzing said image to determine image characteristics;

c) generating a tone scale adjustment model based on said adjusted display source light illumination level and said image characteristics, wherein application of said tone scale adjustment model to said image adjusts pixel code values in said image thereby creating a tone scale adjusted image such that display of said tone scale adjusted image using said adjusted display source light illumination level produces similar output as said pixel code values would produce when displaying said image using a full source light illumination level;

d) applying said tone scale adjustment model to said image to produce a said tone scale adjusted image;

e) computing a high-pass image and a low-pass image from said tone scale adjusted image;

f) applying a gain map function to said high-pass image to produce an adjusted high-pass image;

g) adding said low-pass image to said adjusted high-pass image to form an enhanced image; and

h) coordinating said enhanced image with said adjusted display source light illumination level for display, wherein said coordinating comprises ensuring that said adjusted display source light illumination level is used to control a display source light for all color channels of a display during display of said enhanced image.

7. A method as described in claim 6 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.

8. A method as described in claim 6 wherein said computing a high-pass image comprises low pass filtering 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.

9. A method as described in claim 6 wherein said gain function is related to the slope of the tone scale adjustment model.

10. A method as described in claim 6 wherein said gain function is proportional to the ratio of the slope of the tone scale adjustment model below a maximum fidelity point (MFP) and the slope of the tone scale adjustment model at a specific code value.

11. A method as described in claim 6 wherein said gain map function is proportional to the ratio of the slope of the tone scale adjustment model below a function transition point (FTP) and the slope of the tone scale adjustment model at a specific code value.

12. A method for adjusting an image in coordination with a display source illumination light level, said method comprising:

a) analyzing said image, with a computing device, to determine an adjusted display source light illumination level, wherein said adjusted source light illumination level is used to control a display source light level for all color channels of a display when displaying said image;

b) analyzing said image to determine a tone scale adjustment model, wherein said tone scale adjustment model is also based on said adjusted display source light illumination level;

c) applying said tone scale adjustment model to said image to produce a tone scale adjusted image;

d) computing a high-pass image and a low-pass image from said tone scale adjusted image;

e) applying a gain map function to said high-pass image to produce an adjusted high-pass image; and

f) adding said low-pass image to said adjusted high-pass image to form an enhanced image.

13. A method as described in claim 12 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.

14. A method as described in claim 12 wherein said tone scale adjustment model is dependent on said adjusted source light illumination level.