Color Space Transform Using Parametric LUT Approximation
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Solution Overview
Problem
Existing color transformation techniques, such as 3D LUTs and CDLs, fail to maintain color uniformity across various display devices due to limitations in processing power and proprietary issues, making it difficult to carry color adjustments through the video distribution workflow effectively.
Innovation Solution
A method that determines a transformation table for converting an input color space to an output color space using first and second order approximations, with intermediate terms defined as parametric functions to ensure accurate color representation, implemented in a color adjustment device that can process and compress color metadata for seamless distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a 3D LUT is used for color transformation, then color accuracy is improved, but processing power requirements increase and the transform cannot be carried through the workflow
Solution Approach 1:
The patent segments the 3D LUT into multiple 1D LUTs, one for each color channel (red, green, blue). Instead of storing and processing a complete 3D transformation table, the system uses separate 1D lookup tables for each channel that can be applied independently, significantly reducing processing power requirements while maintaining color transformation capability throughout the workflow
Solution Approach 2:
The patent extracts the essential color transformation parameters from the complex 3D LUT and represents them in a simplified format (Color Decision List) that contains only the necessary metadata for color adjustment. This extracted representation can be carried through the entire workflow from capture to post-production without requiring the full processing power of the original 3D LUT
2Adaptability or versatility
If proprietary CDLs are used for color transformation, then color adjustment capability is improved, but workflow compatibility deteriorates due to proprietary formats
Solution Approach 1:
The patent creates a universal Color Decision List format that can represent color transformations across different devices and workflow stages. The CDL uses standardized parameters (slope, offset, power) that are device-independent and can be applied universally from capture through post-production, eliminating the need for proprietary formats at each workflow stage and enabling seamless color transformation throughout the entire pipeline
3Productivity
If 1D LUTs are used for color transformation, then processing efficiency is improved, but color channel cross-talk correction deteriorates
Solution Approach 1:
The patent introduces an intermediary conversion process that transforms the 3D LUT into a set of 1D LUTs with specific parameters (slope, offset, power) for each color channel. This intermediary representation maintains processing efficiency of 1D LUTs while the parametric form allows for correction of color channel cross-talk through the mathematical relationships defined in the CDL parameters, achieving a balance between efficiency and accuracy
Data Source
AI summary
A method, apparatus and system for transforming a calorimetric adjustment of a sequence of images from an input color space into an output color space includes a color adjustment device for determining a transformation table for converting the input color space of the sequence of images to an output color space, for applying a first order approximation to at least one subset of the sequence of images, the subsets of the sequence of images defined by the transformation table, and if the sequence of images has not reached convergence, for applying a second order approximation to at least one subset of the sequence of images. In one embodiment, the color components of the output color space are defined by a combination of intermediate terms, where the number of the intermediate terms corresponds to the number of input color space components. The transform is configured to survive a video distribution workflow.