Systems and methods for brightness preservation using a smoothed gain image

• US 8,111,265 B2
• Filed: 02/28/2007
• Issued: 02/07/2012
• Est. Priority Date: 12/02/2004
• 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, Zhou, Jin
• Primary Examiner(s): CASCHERA, ANTONIO A
• Application Number:
  US11/680,312
• Publication Number:
  US 20070146236A1
• Time in Patent Office: 1,805 Days
• Field of Search: None
• US Class Current: 345/611
• 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 2320/0626 for control of overall brightness
• 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 2320/0666 for control of colour parameters, e.g. colour temperature
• 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
• CPC Class Codes: G09G 3/3611 Control of matrices with row and column drivers

Abstract

Embodiments of the present invention comprise methods and systems for brightness preservation using a smoothed gain map.

Claims

1. A method for adjusting image code values, said method comprising:

a) receiving a low-pass version of an input image at a computing device;

b) determining a low-pass gain process for said low-pass image;

c) creating a low-pass gain image based on said low-pass gain process;

d) spatially smoothing said low-pass gain image with said computing device;

e) applying said smoothed, low-pass gain image to said low-pass image thereby creating an enhanced low-pass image with said computing device;

f) combining said enhanced low-pass image with a high-pass version of said input image thereby creating an enhanced output image.

2. A method as described in claim 1 further comprising:

a) receiving a high-pass version of said input image;

b) applying a high-pass gain process to said high pass version of said input image thereby creating an enhanced high-pass image with said computing device; and

c) wherein said combining comprises combining said enhanced low-pass image with said enhanced high-pass image.

3. A method as described in claim 1 wherein said low pass version of an input image represents a single chrominance or luminance channel of said input image.

4. A method as described in claim 1 wherein said determining a low-pass gain process comprises creating a tonescale adjustment curve.

5. A method as described in claim 1 wherein said determining a low-pass gain process 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.

6. A method as described in claim 1 wherein said creating a low-pass gain image comprises creating an image comprising multiplicative gain factors corresponding to each element of said low pass version of an input image.

7. A method as described in claim 1 wherein said applying said smoothed, low-pass gain image to said low-pass image comprises multiplying elements of said low-pass gain image by corresponding elements of said low-pass version of an input image.

8. An apparatus for adjusting image code values, said apparatus comprising:

a processor;

memory in electronic communication with said processor;

executable instructions stored in said memory, said instructions being executable to perform;

receiving a low-pass version of an input image;

determining a low-pass gain process for said low-pass image;

creating a low-pass gain image based on said low-pass gain process;

spatially smoothing said low-pass gain image;

applying said smoothed, low-pass gain image to said low-pass image thereby creating an enhanced low-pass image;

combining said enhanced low-pass image with a high-pass version of said input image thereby creating an enhanced output image.

9. An apparatus as described in claim 8, said executable instructions further comprising instructions for:

a) receiving a high-pass version of said input image;

b) applying a high-pass gain process to said high pass version of said input image thereby creating an enhanced high-pass image; and

c) wherein said combiner combines said enhanced low-pass image with said enhanced high-pass image.

10. An apparatus as described in claim 8 wherein said executable instructions further comprise instructions for receiving a low pass version of an input image representing a single chrominance or luminance channel of said input image.

11. An apparatus as described in claim 8 wherein said executable instructions further comprise instructions for determining a tonescale adjustment curve.

12. An apparatus as described in claim 8 wherein said executable instructions further comprise instructions for determining a low-pass gain process comprising 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.

13. An apparatus as described in claim 8 wherein said executable instructions further comprise instructions for creating an image comprising multiplicative gain factors corresponding to each element of said low pass version of an input image.