Contrast ratio enhancement system using black detector

• US 8,089,433 B2
• Filed: 01/11/2006
• Issued: 01/03/2012
• Est. Priority Date: 01/11/2006
• Status: Active Grant

• Current Assignee: TTE Technology Incorporated (TCL Technology Group Corp.)
• Original Assignee: TTE Technology Incorporated (TCL Technology Group Corp.)
• Inventors: Rumreich, Mark Francis, Hague, John Alan
• Primary Examiner(s): Mengistu, Amare
• Assistant Examiner(s): PATEL, PREMAL R
• Application Number:
  US12/160,057
• Publication Number:
  US 20080303759A1
• Time in Patent Office: 2,183 Days
• Field of Search: 345/84, 345/102, 345/89
• US Class Current: 345/84
• CPC Class Codes: G09G 2320/064 by time 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 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

The disclosed embodiments relate to a system and method of enhancing a contrast ratio of a display device. An exemplary method comprises determining a quantity of pixels in a frame of video data having a predetermined level of blackness, comparing the quantity of pixels to a reference value, and modulating an illumination signal based on a quantity of pixels exceeding the reference value.

Claims

1. A method of enhancing a contrast ratio of a display device, the method comprising:

determining a quantity of accumulated pixels having a pixel blackness value between zero and a predetermined level of blackness in a frame of video data;

comparing the quantity of accumulated pixels to a reference value that is indicative of a desired number of accumulated pixels that are in the frame of video data and that have pixel blackness values below the predetermined level of blackness; and

modulating an illumination signal based on a quantity by which the quantity of accumulated pixels exceeds the reference value.

2. The method recited in claim 1, comprising categorizing a plurality of pixels that comprise the frame of video data according to their blackness.

3. The method recited in claim 2, comprising separating subsets of the plurality of pixels into bins based on their blackness.

4. The method recited in claim 3, wherein the plurality of pixels are separated into one of nine bins based on their blackness.

5. The method recited in claim 4, wherein each of the nine bins is associated with a level of blackness value defined by six bits on an eight-bit blackness level scale.

6. The method recited in claim 1, comprising scaling a signal corresponding to a level of blackness and whiteness of the frame of video data.

7. The method recited in claim 1, comprising comparing the quantity of accumulated pixels to a value that is related to a maximum whiteness in the frame of video data.

8. A video system, comprising:

a black horizon finder that is adapted to determine a quantity of accumulated pixels having a pixel blackness value between zero and a predetermined level of blackness in a frame of video data, and adapted to compare the quantity of accumulated pixels to a reference value that is indicative of a desired number of accumulated pixels that are in the frame of video data and that have pixel blackness values below the predetermined level of blackness; and

an illumination source control that modulates an illumination signal of a display device if the quantity of accumulated pixels is greater than the reference value.

9. The system recited in claim 8, wherein the black horizon finder is adapted to categorize a plurality of pixels that comprise the frame of video data according to their blackness.

10. The system recited in claim 9, wherein subsets of the plurality of pixels are separated into bins based on their blackness.

11. The system recited in claim 10, wherein the plurality of pixels are separated into one of nine bins based on their blackness.

12. The system recited in claim 11, wherein each of the nine bins is associated with a level of blackness value defined by six bits on an eight-bit blackness level scale.

13. The system recited in claim 8, wherein the illumination source control is adapted to scale a signal corresponding to a level of blackness of the frame of video data to correspond with a level of whiteness of the frame of video data.

14. The system recited in claim 8, wherein the illumination source control is adapted to compare the quantity of accumulated pixels to a value that is related to a maximum whiteness in the frame of video data.

15. The system recited in claim 8, wherein data provided by the illumination source control is adapted to adjust color pixel values in a gamma corrected domain.

16. A system for enhancing a contrast ratio of a display device, comprising:

a control system, comprising;

means for determining a quantity of accumulated pixels having a pixel blackness value between zero and a predetermined level of blackness in a frame of video data;

means for comparing the quantity of accumulated pixels to a reference value that is indicative of a desired number of accumulated pixels that are in the frame of video data and that have pixel blackness values below the predetermined level of blackness; and

means for modulating an illumination signal based on a quantity by which the quantity of accumulated pixels exceeds the reference value.

17. The system recited in claim 16, wherein the control system comprises means for categorizing a plurality of pixels that comprise the frame of video data according to their blackness.

18. The system recited in claim 17, wherein the control system comprises means for separating subsets of the plurality of pixels into bins based on their blackness.

19. The system recited in claim 18, wherein the control system comprises means for separating the plurality of pixels into one of nine bins based on their blackness.

20. The system recited in claim 19, wherein each of the nine bins is associated with a level of blackness value defined by six bits on an eight-bit blackness level scale.