Dual Look-Up Table Gamma Correction for Color Deviation
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Solution Overview
Problem
Conventional image processing devices face challenges in maintaining accurate color balance across different grayscales, leading to deviations in color coordinates, particularly at low grayscales, due to the use of full white color coordinates for gamma correction, which does not account for variations in red, green, and blue subpixels.
Innovation Solution
An image processing device and method that utilize a first look-up table for white gamma correction values and a second look-up table for red, green, and blue gamma correction values, allowing for interpolation between these values to calculate second image data, thereby correcting image data for white, red, green, and blue grayscales, and improving image quality by reducing color coordinate deviations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If full white color coordinates are used for gamma correction, then the gamma curve can be maintained at 2.2 based on white color coordinates, but color balance deviations occur particularly at low grayscales for red, green, and blue subpixels
Solution Approach 1:
The patent segments the gamma correction process into two distinct look-up tables: one for white grayscale gamma correction and another for color-specific (red, green, blue) gamma correction. This segmentation allows independent optimization of white balance and color accuracy, resolving the contradiction by applying different correction strategies to different color channels based on the input pixel type.
Solution Approach 2:
The patent applies local quality by using different gamma correction values tailored to specific color channels. Instead of a uniform gamma correction for all pixels, the system selects appropriate gamma values from the second look-up table based on the dominant color channel, ensuring that each color component receives optimized correction for its specific characteristics, particularly at low grayscales.
2Device complexity
If a single look-up table with white gamma correction values is used, then the device complexity is low, but color coordinate deviations occur for non-white grayscales
Solution Approach 1:
The patent divides the correction system into two specialized look-up tables rather than using one general table. The first table handles white grayscale correction while the second handles color-specific correction, allowing the system to maintain relatively simple table structures while achieving superior color accuracy through targeted correction values for each color channel.
3Ease of operation
If gamma correction is performed using only white grayscale values, then the processing is simple, but display quality deteriorates due to color coordinate deviations
Solution Approach 1:
The patent performs preliminary classification of input pixels to determine their dominant color channel before applying gamma correction. This preliminary action enables the system to select the appropriate look-up table and correction values in advance, maintaining simple processing flow while ensuring reliable display quality through color-adaptive correction.
Solution Approach 2:
The system applies local quality by adapting the gamma correction process to the specific color characteristics of each pixel. For white pixels, the first look-up table is used; for colored pixels, the second look-up table provides color-specific correction, ensuring that each pixel type receives the most appropriate correction for maintaining display quality.
Data Source
AI summary
An image processing device includes a first look-up table in which first gamma correction values corresponding to a white grayscale are recorded; a second look-up table in which second gamma correction values corresponding to red, green, and blue grayscales are recorded; and a data correcting unit that calculates second image data from received first image data based on a first gamma correction value and a second gamma correction value for the first image data, by referring to the first and second look-up tables.