Local Dimming Gain Control for Display Noise Reduction
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Solution Overview
Problem
Conventional local dimming methods amplify noise and cause color shift in pixel grey levels, especially in dark backgrounds, due to overcompensation of backlight brightness adjustments.
Innovation Solution
A method that divides digital images into blocks, calculates backlight parameters, and adjusts pixel gains based on source and reference brightness ratios to prevent noise amplification, using a gain equation and binarization of backlight parameters into reference ranges to maintain accurate grey levels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If backlight brightness is decreased in local dimming, then contrast is improved, but noise is amplified and color shift occurs
Solution Approach 1:
The patent dynamically adjusts pixel gain based on the ratio of actual source brightness to reference source brightness. When backlight brightness is decreased, the system calculates a compensation gain and applies it to pixel grey levels to maintain accurate color representation, thereby resolving the contradiction between improving contrast and maintaining pixel accuracy.
Solution Approach 2:
The system performs backlight simulation to calculate reference source brightness, compares it with actual source brightness, and uses this feedback to dynamically determine pixel gain. This closed-loop feedback mechanism ensures that noise amplification and color shift are compensated when backlight brightness is adjusted for local dimming.
2Illumination intensity
If pixel gain is increased to compensate for reduced backlight brightness, then brightness compensation is improved, but noise amplification and overcompensation occur
Solution Approach 1:
The patent calculates pixel gain dynamically using the ratio of actual source brightness to reference source brightness, rather than applying a fixed or uniformly increased gain. This adaptive parameter adjustment ensures appropriate compensation without excessive gain that would cause noise amplification or overcompensation, thereby maintaining color accuracy while achieving brightness compensation.
3Illumination intensity
If local dimming is applied to improve contrast, then image quality is improved, but processing complexity increases
Solution Approach 1:
The patent divides the display into multiple blocks and performs separate backlight simulation and gain calculation for each block. This segmentation allows local dimming to be applied independently to different regions, improving contrast where needed while keeping the processing complexity manageable through localized operations rather than global processing.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach dynamically sets pixel gains to prevent noise amplification and overcompensation, ensuring accurate color representation and reduced color shift, particularly in dark regions.
Implementation Method 1
each of the lighting units includes at least one light emitting diode
Data Source
AI summary
The local dimming method includes: dividing a digital image into multiple blocks and calculating a backlight parameter of each of the blocks; performing a backlight simulation based on the backlight parameters to calculate source brightness of each pixel; quantifying the backlight parameters into multiple reference backlight parameters according to numerical ranges; performing the backlight simulation based on the reference backlight parameters to calculate reference source brightness of each pixel; for each of the pixels, setting a gain of the pixel to be less than or equal to a first value if the corresponding reference source brightness is equal to the darkest backlight parameter, otherwise determining the gain of the pixel according to a ratio of the source brightness to the reference source brightness; adjusting grey levels of the pixels according to the gains to obtain adjusted grey levels and driving the display panel according to the adjusted grey levels.