Global nonlinear scaler for multiple pixel gamma response compensation

Patent metadata

Field	Value
Publication number	US-12340737-B2
Application number	US-202318509592-A
Country	US
Kind code	B2
Filing date	Nov 15, 2023
Priority date	Dec 16, 2022
Publication date	Jun 24, 2025
Grant date	Jun 24, 2025

Abstract

In a display characterized by regions with different pixel responses due, for example, to local pixel density variation, voltage-to-luminance matching may be non-universal. Therefore, in order to avoid visual artifacts that may hinder a desired visualization of displayed content, it may be advantageous to compensate the different gamma responses. In some cases, such as with electronic devices having a single pixel density across the display, optical calibration may be performed to determine voltage-to-luminance matching. However, in electronic devices with local pixel density variations, it may be disadvantageous to perform optical calibrations for each region with a different pixel density. Instead of using two distinct gamma curves which may include dedicated optical calibration, a global nonlinear scaler (GNLS) compensation may be applied. Embodiments may pertain to techniques for applying a per-channel and band-global gamma-to-voltage compensation to reduce or minimize a relative luminance error amongst different responses of display regions.

First claim

What is claimed is:

1. An electronic device comprising:
an electronic display comprising a first display region associated with first gamma response characteristics and a second display region associated with second gamma response characteristics; and
processing circuitry configured to:
receive a gray level value corresponding to a first pixel of the second display region;
convert the gray level value to a first digital voltage value, the first digital voltage value configured to provide a first gamma conversion corresponding to the first gamma response characteristics;
apply an offset to the first digital voltage value to obtain a second digital voltage value corresponding to the second gamma response characteristics; and
output the second digital voltage value to a digital-to-analog converter (DAC) to obtain an analog voltage corresponding to the second display region.

2. The electronic device of claim 1 , wherein the first display region comprises a first gray level-to-voltage relationship and the second display region comprises a second gray level-to-voltage relationship.

3. The electronic device of claim 2 , wherein the first gray level-to-voltage relationship is determined based on an optical calibration of the first display region.

4. The electronic device of claim 2 , wherein the second gray level-to-voltage relationship is determined based on the first gray level-to-voltage relationship and the offset.

5. The electronic device of claim 2 , wherein the first gray level-to-voltage relationship is stored in a lookup table.

6. The electronic device of claim 1 , wherein the electronic display comprises a third display region, the third display region comprising a first pixel density greater than or equal to a second pixel density of the first display region.

7. The electronic device of claim 6 , wherein the second display region is disposed between the first display region and the third display region.

8. A method, comprising:
receiving, at global nonlinear scaler (GNLS) compensation circuitry, a first gamma voltage value corresponding to a first pixel of a first display region or a second pixel of a second display region, the first display region comprising a first pixel density and the second display region comprising a second pixel density;
applying an offset to the first gamma voltage value to obtain a second gamma voltage value corresponding to a third pixel of a third display region to reduce a luminance error associated with the third display region; and
outputting the second gamma voltage value to a digital-to-analog converter (DAC).

9. The method of claim 8 , wherein the first pixel density is greater than the second pixel density.

10. The method of claim 8 , wherein the GNLS compensation circuitry is configured to receive the first gamma voltage value corresponding to the first pixel of the first display region or the second pixel of the second display region based on a luminance response associated with the third display region.

11. The method of claim 10 , wherein the luminance response associated with the third display region comprises a gamma response.

12. The method of claim 8 , comprising:
wherein the GNLS compensation circuitry receives the first gamma voltage value from a first lookup table comprising an indication of a first number of tap points.

13. The method of claim 12 , wherein the offset is obtained via a second lookup table comprising an indication of a second number of tap points, wherein the second number of tap points is less than the first number of tap points.

14. The method of claim 8 , wherein applying the offset reduces the luminance error associated with the third display region.

15. The method of claim 8 , wherein the third display region is positioned between the first display region and the second display region.

16. A tangible, non-transitory medium, comprising computer-readable instructions configured to, when executed, cause one or more processors to:
select a first gamma voltage value from a first lookup table corresponding to a first display region or a second gamma voltage value from a second lookup table corresponding to a second display region; and
apply an offset to the first gamma voltage value or the second gamma voltage value, the offset based on a third lookup table, wherein applying the offset reduces a luminance error associated with a third display region.

17. The tangible, non-transitory medium of claim 16 , wherein the first display region comprises a first pixel density, the second display region comprise a second pixel density, and the first pixel density is greater than the second pixel density.

18. The tangible, non-transitory medium of claim 16 , comprising computer-readable instructions configured to, when executed, cause the one or more processors to generate, based on the offset applied to the first gamma voltage value or the second gamma voltage value, a third gamma voltage value.

19. The tangible, non-transitory medium of claim 18 , comprising computer-readable instructions configured to, when executed, cause the one or more processors to:
output an indication of the second gamma voltage value to a digital-to-analog converter (DAC); and
cause the DAC to select an adjusted tap point based on the indication of the second gamma voltage value.

20. The tangible, non-transitory medium of claim 16 , wherein the first lookup table comprises an indication of a first number of tap points, the second lookup table comprises a second indication of a second number of tap points, and the third lookup table comprises a third indication of a third number of tap points, wherein the third number of tap points is less than the first number of tap points and the second number of tap points.

Assignees

• Apple Inc

Inventors

• Miscuglio Mario
• Brahma Kingsuk
• Ryu Jie Won
• Gao Shengkui
• Che Yuchi
• Williams Graeme M
• Qiao Yi
• Yao Wei H
• Guillou Jean-Pierre S

Classifications

• G09G3/32 Primary

  semiconductive, e.g. using light-emitting diodes [LED] · CPC title

• G09G2320/0276

  for the purpose of adaptation to the characteristics of a display device, i.e. gamma correction · CPC title

• G09G2300/0828

  forming a digital to analog [D/A] conversion circuit · CPC title

• G09G3/3208 Primary

  organic, e.g. using organic light-emitting diodes [OLED] · CPC title