3D-LUT Color Correction for Independent Lightness and Chroma Adjustment
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Solution Overview
Problem
Conventional electronic still cameras face challenges in flexibly adjusting image quality without deteriorating it, particularly due to issues with chroma correction leading to lightness changes and difficulty in adjusting specific areas of the color space, which affects the natural appearance of images and requires complex operations.
Innovation Solution
An imaging device equipped with a three-dimensional look-up table (3D-LUT) for color adjustment, allowing for independent correction of lightness and chroma without changing the other, enabling precise adjustment of representative colors and preventing mutual effects between similar hues, thus enhancing image quality correction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If chroma correction is implemented by linear transformation on a color difference plane, then chroma adjustment is achieved, but lightness changes occur which deteriorate image quality
Solution Approach 1:
The patent segments the color correction process into independent lightness correction and chroma correction components. By separating these functions, the system can adjust chroma without inadvertently changing lightness, thus preventing the quality deterioration caused by coupled transformations in conventional linear methods.
Solution Approach 2:
The patent applies different correction strategies to different regions of the color space. Specifically, it uses a lookup table with predetermined correction values for specific color regions, allowing localized adjustment of chroma while preserving lightness in each region, rather than applying a global linear transformation that affects all regions uniformly.
2Adaptability or versatility
If grayscale correction and chroma correction are applied to the entire color space, then comprehensive color adjustment is achieved, but flexible correction of specific areas becomes difficult
Solution Approach 1:
The patent divides the color space into multiple regions and applies different correction characteristics to each region through a segmented lookup table. This allows comprehensive coverage of the entire color space while enabling flexible, area-specific correction by simply changing the lookup table data without modifying the overall system architecture.
Solution Approach 2:
The patent changes the parameters stored in the lookup table to achieve different correction effects for different color regions. By modifying the predetermined correction values in the lookup table rather than the correction algorithm itself, the system can flexibly adjust specific areas of the color space while maintaining comprehensive color adjustment capability.
3Measurement precision
If adjustment operations are performed on representative colors, then color accuracy is improved, but mutual effects between similar hues occur making adequate adjustment of all colors impossible
Solution Approach 1:
The patent segments the color space into distinct regions with clear boundaries, assigning each representative color to a specific region. The lookup table provides independent correction values for each region, preventing mutual effects between similar hues while maintaining accurate adjustment of all representative colors through non-overlapping correction zones.
4Device complexity
If conventional chroma correction methods are used, then processing simplicity is maintained, but lightness changes occur requiring complex operations to prevent deterioration
Solution Approach 1:
The patent introduces a lookup table as an intermediary between the chroma correction process and the final output. This lookup table pre-stores correction values that inherently preserve lightness while adjusting chroma, eliminating the need for complex real-time calculations and additional correction steps that would otherwise be required to prevent lightness changes.
Data Source
AI summary
The present invention relates to an imaging device and a method of processing an imaging result in an imaging device, and is applied to e.g. an electronic still camera to thereby allow the camera to correct image quality readily and flexibly with avoiding the deterioration of the image quality effectively. In the present invention, a three-dimensional look-up table is provided and an imaging result (Y2, Cb2, Cr2) is corrected by use of the three-dimensional look-up table.