Backlight Luminance Estimation for LCD Contrast
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Solution Overview
Problem
Conventional image display devices using local dimming struggle to accurately set pixel gradations based on varying luminances of light-emitting regions, leading to suboptimal image contrast due to incomplete luminance estimation under pixels.
Innovation Solution
An image display method that generates luminance setting data for backlight regions, luminance estimation data for pixels, and gradation setting data for liquid crystal panels, using a controller to adjust backlight and liquid crystal panel settings based on input images, accounting for luminance profiles and light leakage between regions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If local dimming is implemented with multiple light-emitting regions, then image contrast is improved, but luminance estimation accuracy deteriorates due to light leakage between regions
Solution Approach 1:
The backlight is divided into multiple independently controllable light-emitting regions (first light-emitting region and second light-emitting region), allowing separate luminance control for different image areas to improve contrast while managing light leakage effects
Solution Approach 2:
The system calculates actual luminance values by considering both the set luminance values and the luminance profile data that represents light leakage between adjacent regions. This feedback mechanism adjusts the luminance estimation to account for the optical coupling between regions, improving measurement precision
2Manufacturing precision
If gradations are corrected based on estimated luminances, then pixel display accuracy is improved, but image contrast deteriorates due to incomplete luminance estimation
Solution Approach 1:
The luminance correction process uses feedback from luminance profile data to adjust gradation settings. By incorporating information about light leakage between regions, the system can accurately estimate actual luminances and apply appropriate corrections to maintain both pixel accuracy and image contrast
Solution Approach 2:
The system dynamically adjusts gradation parameters based on calculated luminance values that account for light leakage. By changing the gradation settings according to the actual luminance distribution rather than just the set values, the system maintains display accuracy while preserving contrast
Data Source
AI summary
A method includes generating luminance setting data, luminance estimation data, maximum luminance data, and gradation setting data, and controlling a backlight panel and a liquid crystal panel based on the luminance setting data and the gradation setting data, respectively. The luminance setting data sets a luminance value for each light-emitting region of the backlight panel and is generated based on an input image. The luminance estimation data indicates an estimated luminance value of backlight for the input image with respect to each pixel of the liquid crystal panel and is generated based on the luminance setting data and luminance profile data. The maximum luminance data is generated based on the luminance estimation data. The gradation setting data sets a gradation value of each pixel of the liquid crystal panel for the input image, and is generated based on the input image, the luminance estimation data, and the maximum luminance data.