Methods and systems for backlight modulation with image characteristic mapping

• US 8,203,579 B2
• Filed: 12/26/2007
• Issued: 06/19/2012
• 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:
  US11/964,683
• Publication Number:
  US 20090167789A1
• Time in Patent Office: 1,637 Days
• Field of Search: 345/77, 345 82- 83, 345 88- 89, 345/102, 345/204, 345/207, 345/214, 345/690
• US Class Current: 345/690
• 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 2320/0276 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 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 2330/022 in absence of operation, e.g. no data being entered during a predetermined time
• CPC Class Codes: G09G 2360/144 the light being ambient light
• CPC Class Codes: G09G 2360/145 the light originating from the display screen
• 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
• CPC Class Codes: G09G 5/02 characterised by the way in which colour is displayed details of colour display specific for CRTs G09G1/28; specific for flat matrix panels other than liquid crystal displays G09G3/2003; specific for liquid crystal displays G09G3/3607

Abstract

Elements of the present invention relate to systems and methods for selecting a display source light illumination level. Aspects of some embodiments also comprise methods and systems for temporal filtering of a display source light illumination level.

Claims

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

a) generating an image histogram for an image to be displayed on a display device;

b) receiving image histogram data and a user-selected one of a plurality of stored maps at a mapping module, each map associating an image pixel brightness characteristic to a display model maximum brightness attribute;

c) determining an image pixel brightness characteristic based on said histogram data;

d) associating said display model maximum brightness attribute with said image pixel brightness characteristic using the selected said map and said mapping module;

e) generating a display model based on said user-selected output brightness level and said display model maximum brightness attribute;

f) calculating model clipping limits for said display model;

g) calculating a display error vector for each of a plurality of source light illumination levels;

h) combining said display error vectors with said histogram data to determine a distortion value for said plurality of source light illumination levels; and

i) selecting a source light illumination level based on said distortion values.

2. A method as described in claim 1 further comprising receiving ambient light sensor input at said mapping module, wherein said map is selected based on said ambient light sensor input.

3. A method as described in claim 1 further comprising receiving user input comprising a user brightness selection at said mapping module, wherein said map is modified based on said user brightness selection.

4. A method as described in claim 1 wherein said image characteristic is an image average pixel level (APL).

5. A method as described in claim 1 wherein said display model attribute is an ideal display maximum output value.

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

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

a) generating an image histogram for an image to be displayed on a display device;

b) receiving image histogram data at a mapping module comprising a map that associates an image characteristic to a display model attribute, said map being selected from among a plurality of stored maps based on user input;

c) modifying said map based on receipt of a user-selected output brightness selection;

d) determining an image characteristic based on said histogram data;

e) determining a display model attribute that is associated with said image characteristic using said map and said mapping module;

f) generating a display model based on said display model attribute;

g) calculating model clipping limits for said display model;

h) calculating a display error vector for each of a plurality of source light illumination levels;

i) combining said display error vectors with said histogram data to determine a distortion value for said plurality of source light illumination levels;

j) selecting a source light illumination level based on said distortion values;

k) filtering said source light illumination level with a selective temporal filter that is responsive to said user brightness selection.

8. A method as described in claim 7 wherein said filter is applied to said source light illumination level when a user brightness selection is not received and said filter is not applied to said source light illumination level when said user brightness selection is received.

9. A method as described in claim 7 wherein a first configuration of said filter is applied to said source light illumination level when a user brightness selection is not received and a second configuration of said filter is applied to said source light illumination level when said user brightness selection is received.