Scaled Gamma Curve for Uniform Display Brightness
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Solution Overview
Problem
Display devices face challenges in maintaining a smooth, uniform brightness transition between local high brightness regions and background regions, often resulting in jagged boundaries or abrupt changes, which can lead to a poor appearance during optical fingerprint recognition and image display.
Innovation Solution
A display driver with control circuitry that stores a default gamma curve and determines a scale factor based on the ratio of in-region to total pixels, applying a modified gamma transformation to generate output voltage data for target pixels, thereby adjusting the brightness levels and smoothing transitions between regions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a default gamma curve is applied uniformly across the entire display panel, then the image display is simple and consistent, but the brightness transition between local high brightness regions and background regions becomes abrupt and jagged
Solution Approach 1:
The patent applies different gamma curves to different regions of the display panel. Specifically, a first gamma curve is applied to a first region and a second gamma curve is applied to a second region, allowing each region to have optimized brightness characteristics. This resolves the contradiction by making the gamma curve application locally adaptive rather than uniformly global, thereby achieving smooth brightness transitions at region boundaries while maintaining processing simplicity through the use of standard gamma curve transformations.
2Illumination intensity
If the brightness level of a predetermined region is increased for optical fingerprint recognition, then the finger illumination is improved, but the boundary between the high brightness region and background region becomes jagged and visually appealing
Solution Approach 1:
The patent changes the gamma curve parameters specifically for pixels in the predetermined region used for optical fingerprint recognition. By applying a modified gamma transformation to pixels in this region, the brightness is increased to improve finger illumination. The gamma curve adjustment ensures that the parameter changes are gradual and controlled, which smooths the boundary transitions between the high brightness region and the background, eliminating jagged edges while achieving the required illumination level.
Data Source
AI summary
A display driver comprises control circuitry configured to store a default gamma curve, determine a count of in-region pixels of a target pixel in a display panel and neighboring pixels of the target pixel, the in-region pixels being located in a predetermined region of the display panel, and determine a scale factor based on a ratio of the count of the in-region pixels to a total number of the target pixel and the neighboring pixels. The control circuitry also determines a modified gamma curve by scaling the default gamma curve with the scale factor. The display driver further comprises image processing circuitry configured to apply a gamma transformation based on the modified gamma curve to image data defined for the target pixel to generate output voltage data for the target pixel.