Backlight Compensation for Local Dimming Without Gamma Shift
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Solution Overview
Problem
Conventional sub-millimeter LED displays face issues with maintaining optical performance during local dimming, leading to reduced resolution and image distortion due to changes in gamma value and luminance compensation methods causing halos and further resolution loss.
Innovation Solution
A display and backlight compensation method that adjusts backlight luminance based on area peak luminance and windows size dependency, maintaining optical quality without reducing resolution by compensating for luminance differences through local dimming.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If local dimming is performed with conventional algorithms focused on power saving, then power consumption is reduced, but gamma value changes from 2.2 to 2.8 causing image distortion and resolution loss
Solution Approach 1:
The patent applies parameter changes by dynamically adjusting the gamma value based on window size. When window size is small, the gamma value is adjusted to 2.8 to compensate for luminance changes; when window size is large, the gamma value is maintained at 2.2. This dynamic parameter adjustment resolves the contradiction by allowing power-saving local dimming while preventing image distortion through adaptive gamma correction.
2Illumination intensity
If luminance compensation is performed by using extended light source or directly increasing luminance of image data, then luminance compensation is achieved, but halo is generated and resolution is reduced
Solution Approach 1:
The patent applies local quality by performing luminance compensation at the area level rather than globally. The display screen is divided into multiple areas, and luminance compensation is applied locally to each area based on its peak luminance and the halo effect magnitude. This localized approach compensates for luminance differences without generating halos that would reduce overall image resolution.
Solution Approach 2:
The patent applies dynamics by making the luminance compensation adjustable based on window size and area characteristics. The compensation amount is dynamically determined by calculating the product of area peak luminance and luminance dependency of window size. This dynamic adjustment allows optimal compensation without fixed extended light sources that would cause halos and resolution loss.
3Use of energy by moving object
If local dimming is performed without adjusting for windows size, then power saving is achieved, but luminance and gamma value cannot be maintained under different windows sizes
Solution Approach 1:
The patent applies dynamics by making the local dimming algorithm adaptive to window size. The luminance dependency of window size is calculated and used to adjust the luminance compensation amount. This allows the system to maintain consistent luminance and gamma values across different window sizes while still achieving power savings through localized dimming, rather than using a fixed dimming approach.
Data Source
AI summary
A display and a backlight compensation method thereof are provided, wherein the display includes a backlight unit and a driving unit, and the backlight compensation method includes: providing a gamma value of the display; performing local dimming of the backlight unit according to the gamma value; obtaining an area peak luminance of each area in the backlight unit; obtaining a windows size of the backlight unit and a corresponding luminance dependency of windows size; obtaining, by the driving unit, a first display luminance corresponding to each area in the backlight unit according to a product of the area peak luminance of each area and the luminance dependency of windows size; and performing luminance compensation in each area of the backlight unit according to the first display luminance. A backlight compensation method that maintains optical quality is achieved, which can maintain brightness and gamma values under different windows sizes.