Gamma Uniformity Correction Method and System

• US 20080068396A1
• Filed: 09/19/2006
• Published: 03/20/2008
• Est. Priority Date: 09/19/2006
• Status: Abandoned Application

• Current Assignee: Tvia, Inc.
• Original Assignee: Tvia, Inc.
• Inventors: Ishii, Takatoshi
• Application Number:
  US11/533,309
• Publication Number:
  US 20080068396A1
• Time in Patent Office: Days
• US Class Current: 345/601
• CPC Class Codes: G09G 2320/0233 Improving the luminance or brightness uniformity across the screen
• CPC Class Codes: G09G 2320/0238 Improving the black level
• 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 2320/0285 using tables for spatial correction of display data
• CPC Class Codes: G09G 2340/02 Handling of images in compressed format, e.g. JPEG, MPEG
• CPC Class Codes: G09G 3/2055 the pattern being varied in time
• CPC Class Codes: G09G 3/3611 Control of matrices with row and column drivers
• CPC Class Codes: G09G 3/3648 using an active matrix G09G3/367 - G09G3/3696 take precedence

Abstract

A method and system are provided for performing gamma correction on display data. Aspects the exemplary embodiment include using at least a portion of the display data to fetch in parallel from a table memory a gamma correction data value stored at an odd address and a gamma correction data value stored at an even address; detecting when the display data comprises a low address; and in response to detecting that the display data comprises a low address, performing a right shift on the gamma correction data values, thereby decreasing the values of the gamma correction data prior to performing interpolation on the gamma compensation data values.

Claims

1. A method for performing gamma correction on display data, comprising:

using at least a portion of the display data to fetch in parallel from a table memory a gamma correction data value stored at an odd address and a gamma correction data value stored at an even address;

detecting when the display data comprises a low address; and

in response to detecting that the display data comprises a low address, performing a right shift on the gamma correction data values, thereby decreasing the values of the gamma correction data prior to performing interpolation on the gamma compensation data values.

2. The method of claim 1 wherein detecting a low address of the display data further includes determining that the gamma compensated data values from the odd and even addresses originated from low address regions of the table memory.

3. The method of claim 1 wherein a size of the table memory is reduced by compressing the gamma compensation data during a configuration stage, and using interpolation during operation of a display device to decompress the gamma compensation data and to apply the interpolated gamma compensation data to the display data.

4. The method of claim 2 wherein the display data is received having a first bit length, but only a subset of the display data is used as an index to the table memory to reduce the size of the table memory, and wherein interpolation is performed on the gamma compensation data retrieved from the table memory such that gamma corrected display data is produced having a larger bit length than the display data.

5. The method of claim 4 wherein the both the display data and the gamma compensation data stored in the table memory are 10 bits in length, and the interpolated gamma corrected display data 508 has a bit length of 12 bits.

6. The method of claim 2 wherein the table memory is configured as two memories, an odd most significant bit (MSB) address memory for storing odd most significant bit addresses, and an even most significant bit (MSB) address memory for storing even most significant bit addresses.

7. The method of claim 6 wherein the odd and even MSB memories are capable of 8-bit address input and include 128 addresses and 10-bit gamma compensation data for red, green, blue each.

8. The method of claim 1 wherein the display data is used to read the table memory by being separated into a most significant bit (MSB) part and a least significant (LSB) part.

9. The method of claim 8 wherein data from the MSB part becomes memory addresses for both an odd table memory and an even table memory.

10. The method of claim 9 wherein the display data is 10-bits in length, and wherein the MSB part comprises most significant bits 9 through 2 of the display data and is 8-bits in length, and the LSB part comprises bits 0 and 1 the display data and is 2-bits in length.

11. The method of claim 10 wherein the MSB part is further converted into a 7-bit MSB block address comprising bits 9 through 3 of the display data, and a MSB even/odd (E/O) bit comprising a bit 2 of the display data.

12. A gamma correction lookup table (GLUT), comprising:

a table memory for storing gamma compensation data values;

an address module coupled to the table memory, the address module for receiving display data and for using at least a portion of the display data to fetch in parallel from the table memory a gamma correction data value stored at an odd address and a gamma correction data value stored at an even address;

means coupled to the address module for detecting when the display data comprises a low address, and

in response to detecting that the display data comprises a low address, performing a right shift on the gamma correction data values, thereby decreasing the values of the gamma correction data prior to interpolation being performed on the gamma compensation data values.

13. The GLUT of claim 12 wherein a size of the table memory is reduced by compressing the gamma compensation data during a configuration stage, and using interpolation during operation of a display device to decompress the gamma compensation data and to apply the interpolated gamma compensation data to the display data.

14. The GLUT of claim 13 wherein the display data received by the address module has a first bit length, but only a subset of the display data is used as an index to the table memory to reduce the size of the table memory.

15. The GLUT of claim 14 wherein the GLUT further includes an interpolator module for performing interpolation on the gamma compensation data retrieved from the table memory such that gamma corrected display data is produced having a larger bit length than the display data.

16. The GLUT of claim 15 wherein the both the display data and the gamma compensation data stored in the table memory are 10 bits in length, and the interpolated gamma corrected display data has a bit length of 12 bits.

17. The GLUT of claim 12 wherein the table memory is configured as two memories, an odd most significant bit (MSB) address memory for storing odd most significant bit addresses, and an even most significant bit (MSB) address memory for storing even most significant bit addresses.

18. The GLUT of claim 17 wherein the odd and even MSB memories are capable of 8-bit address input and include 128 addresses and 10-bit gamma compensation data for red, green, blue each.

19. The GLUT of claim 12 wherein the address module separates the display data into a most significant bit (MSB) part and a least significant (LSB) part.

20. The GLUT of claim 19 wherein data from the MSB part becomes memory addresses for both an odd table memory and an even table memory.

21. The GLUT of claim 20 wherein the display data is 10-bits in length, and wherein the MSB part comprises most significant bits 9 through 2 of the display data and is 8-bits in length, and the LSB part comprises bits 0 and 1 the display data and is 2-bits in length.

22. The GLUT of claim 21 wherein the address module for the converts the MSB part into a 7-bit MSB block address comprising bits 9 through 3 of the display data, and a MSB even/odd (E/O) bit comprising a bit 2 of the display data.

23. The GLUT of claim 22 wherein the interpolator module comprises a most significant bit data multiplexer, a subtractor, a multiplier, and an adder, wherein the data multiplexer converts the 10-bit gamma compensation data values from the table memory module into a 12-bit upper value and a 12-bit base value, such that interpolation is performed between the upper and base values with input from LSB part of the input data.

24. The GLUT of claim 22 further comprising a multiplexer control coupled between the address module and the interpolator module where in the multiplexer control controls the data multiplexer sets that it can be determined whether display data comprises a low address by examining bits 9 and 8 of the display data.

25. The GLUT of claim 24 wherein the multiplexer control determines that the display data comprises a low address when bits 9 and 8 of the display data are zero.

26. The GLUT of claim 25 wherein in response to a low address signal from the multiplexer control, the data multiplexer shifts

the gamma compensated data values output of the table memory module 2-bits right and fills bits 9 and 8 with zeros,

in response to no an absence of the low address signal, the data multiplexer concatenates two LSB zero bits to a right side of the gamma compensated data values;

and

outputs the 12-bit upper and lower base values.

27. The GLUT of claim 22 wherein interpolator module performs interpolation between the upper and base values to generate the gamma corrected display data by,

subtracting the base value from the upper value using the subtracter to generate a delta value;

multiplying the LSB part with the delta value using the multiplier to generate a multiplier output; and

adding multiplier output with the base value using a matter to generate 12-bit gamma corrected display data.

28. A gamma correction lookup table, comprising:

means for using at least a portion of the display data to fetch in parallel from a table memory a gamma correction data value stored at an odd address and a gamma correction data value stored at an even address;

means for detecting when the display data comprises a low address;

means responsive to detecting that the display data comprises a low address for performing a right shift on the gamma correction data values, thereby decreasing the values of the gamma correction data prior to performing interpolation on the gamma compensation data values.