Perceptually Accurate Image Rendering via QTD Color Space
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Solution Overview
Problem
Existing color rendering technologies face challenges in achieving perceptually accurate image reproduction, particularly when transforming linear RGB or XYZ values for High Dynamic Range (HDR) applications, as they often result in chromatic distortions due to the use of singular Electro-Optic Transfer Functions (EOTFs) that were originally developed for CRTs, which do not account for modern digital image processing.
Innovation Solution
A method and system that utilize a multidimensional EOTF transformation, specifically the QTD color space, which maintains hue and chroma while transforming RGB values into universal perceived brightness (Bp) and chroma (Cp) values, allowing for scaling and transmission of colorant data to ensure accurate and distortion-free image reproduction across various devices.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a singular EOTF is used to transform RGB components for HDR, then brightness and dynamic range are increased, but chromatic distortions occur
Solution Approach 1:
The patent segments the color transformation process into separate chromaticity and luminance components. By decomposing the EOTF application into independent chromaticity preservation and luminance enhancement stages, the system avoids chromatic distortions while achieving HDR brightness levels. The chromaticity coordinates (u,v) are extracted and preserved separately from the luminance transformation.
Solution Approach 2:
The patent applies different transformation rules to different aspects of color data. Chromaticity information is transformed using one method (preserving hue and saturation relationships) while luminance is transformed using the HDR EOTF. This local differentiation ensures that brightness enhancement does not compromise color accuracy.
2Adaptability or versatility
If traditional color spaces are used for color transformation, then compatibility is maintained, but perceptual accuracy deteriorates
Solution Approach 1:
The patent introduces an intermediary colorimetric space that bridges traditional RGB compatibility and perceptual accuracy requirements. By transforming through an intermediate representation that separates chromaticity from luminance, the system maintains compatibility with standard color spaces while achieving superior perceptual accuracy in the final HDR output.
3Productivity
If nonlinear EOTF transformation is applied to increase dynamic range, then HDR capability is achieved, but chromatic distortion increases
Solution Approach 1:
The patent segments the nonlinear EOTF transformation into chromaticity-preserving and luminance-enhancing operations. By applying the nonlinear transformation only to the luminance component while preserving chromaticity coordinates, the system achieves extended dynamic range without compromising color fidelity.
Solution Approach 2:
The patent changes the parameter representation from standard RGB to a separated chromaticity-luminance format. This parameter transformation allows independent control of chromaticity (hue, saturation) and luminance (brightness), enabling nonlinear luminance scaling without affecting chromatic accuracy.
Data Source
AI summary
An image reproduction system and methods for providing colorant data to an end device. A method includes extracting general HSV value data for each pixel of an image from image data. For each pixel, the general HSV value data is transformed to generate universal perceived brightness, Bp, and universal perceived chroma, Cp, value data. End-device colorant data associated with the general HSV value data is retrieved for each pixel and scaled using the Bp and Cp value data to obtain scaled end-device colorant data. The scaled end-device colorant data is transmitted to the end device.