Local Dimming Spatial Filtering for LCD Luminance Uniformity
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The local dimming method in LCD devices results in luminance deviations at the same gray scale due to dimming differences between blocks, leading to a halo phenomenon that deteriorates image quality.
Innovation Solution
A local dimming driving method that analyzes input image data in blocks, performs spatial filtering to control local dimming values, and calculates a gain value to compensate the data, reducing dimming differences between blocks by repeating spatial filtering based on the light profile of the backlight unit.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If local dimming method is used to control luminance of backlight unit on block-by-block basis, then power consumption is reduced and contrast ratio is improved, but luminance deviation occurs at the same gray scale due to dimming difference between blocks
Solution Approach 1:
The patent applies local quality by differentiating the treatment of different blocks based on their luminance characteristics. Blocks with high luminance values undergo spatial filtering to reduce their intensity, while blocks with low luminance values are preserved. This selective processing maintains the power-saving benefits of local dimming while correcting the luminance uniformity issue in specific regions where halo phenomena occur.
Solution Approach 2:
The patent changes the luminance parameter of specific blocks by applying spatial filtering to high luminance blocks. This parameter transformation reduces the luminance deviation between adjacent blocks with different gray scale values, thereby eliminating the halo phenomenon while preserving the overall local dimming effect for power consumption reduction.
2Measurement precision
If local dimming method is used to control luminance of backlight unit on block-by-block basis, then contrast ratio is improved, but halo phenomenon occurs due to light leakage difference between neighboring blocks
Solution Approach 1:
The patent applies local quality by differentiating the treatment of different blocks based on their luminance characteristics. Blocks with high luminance values undergo spatial filtering to reduce their intensity, while blocks with low luminance values are preserved. This selective processing maintains the contrast ratio improvement benefits of local dimming while correcting the luminance uniformity issue in specific regions where halo phenomena occur.
Solution Approach 2:
The patent converts the harmful halo phenomenon into a benefit by identifying high luminance blocks as the source of the problem and applying targeted spatial filtering. The spatial filtering process transforms the excessive luminance in specific blocks, converting the harmful light leakage effect into a controlled luminance distribution that eliminates halos while preserving the intended contrast enhancement.
3Manufacturing precision
If spatial filtering is applied to local dimming value per block, then luminance deviation is reduced, but processing complexity increases
Solution Approach 1:
The patent applies partial action by performing spatial filtering only on blocks that exceed a predetermined luminance threshold, rather than processing all blocks uniformly. This selective approach reduces the overall processing complexity while still achieving luminance uniformity in the critical regions where halo phenomena occur, balancing the trade-off between image quality and processing load.
Data Source
AI summary
Disclosed herein is a local dimming driving method and device of an LCD device, which is capable of minimizing luminance deviation at the same gray scale due to a dimming difference between blocks. The local dimming driving method of the LCD device includes analyzing input image data in units of blocks and determining a local dimming value per block, performing spatial filtering with respect to the local dimming value per block, repeating spatial filtering by a predetermined repeat count, and controlling luminance of a backlight unit on a block-by-block basis using the local dimming value per block controlled by spatial filtering.