HDR Image Reshaping Mappings for Reversible SDR Conversion
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Solution Overview
Problem
Existing image processing technologies struggle to efficiently convert between standard dynamic range (SDR) and high dynamic range (HDR) images while maintaining color accuracy and reversibility, leading to issues with downstream device compatibility and image quality.
Innovation Solution
Implementing tensor-product B-Spline (TPB) based image reshaping solutions with robust predictors in video codecs to handle transmission errors, minimize power consumption, and optimize HDR-to-SDR mappings, using optimized forward and backward reshaping operations to generate high-quality reconstructed images.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If existing image processing technologies are used to convert between SDR and HDR images, then conversion can be performed, but color accuracy is not preserved and reversibility is not maintained
Solution Approach 1:
The patent applies preliminary action by pre-computing and storing forward and backward reshaping mappings in lookup tables before actual image conversion. The forward mapping table stores HDR-to-SDR conversion data, and the backward mapping table stores SDR-to-HDR conversion data. This pre-computation ensures that when conversion is needed, the exact reverse mapping is already available, guaranteeing both color accuracy preservation and reversibility without real-time computational overhead.
2Manufacturing precision
If complex reshaping operations are implemented to maintain reversibility, then conversion accuracy improves, but processing time increases and power consumption rises
Solution Approach 1:
The patent pre-computes complex reshaping mappings and stores them in lookup tables during a setup phase. The forward reshaping mapping table and backward reshaping mapping table are prepared in advance, containing all necessary conversion data for the full dynamic range. During actual image conversion, the system simply performs table lookups and interpolation, reducing processing time significantly while maintaining high conversion accuracy through the pre-computed mappings.
3Reliability
If robust error handling is implemented in video codecs, then transmission reliability improves, but data overhead increases
Solution Approach 1:
The patent introduces an intermediary mechanism by using prediction structures that reference previously decoded frames and mapping tables. Instead of transmitting complete reshaping data for every frame, the system uses prediction to estimate current frame mappings based on historical data, with error detection and correction mechanisms that verify integrity without requiring excessive redundant data transmission.
4Use of energy by moving object
If optimized reshaping mappings are used to reduce power consumption, then energy efficiency improves, but implementation complexity increases
Solution Approach 1:
The patent applies preliminary action by pre-computing optimized reshaping mappings and storing them in lookup tables. The forward and backward mapping tables are generated in advance using optimization algorithms, but once computed, they are stored and reused for multiple conversions. This shifts the computational complexity from the conversion phase to the setup phase, making real-time conversions energy-efficient while maintaining implementation feasibility through the use of pre-computed data structures.
Data Source
AI summary
HDR color patches are sampled throughout an HDR color space parameterized by a parameter. Reference SDR color patches, input HDR color patches and reference HDR color patches are generated from the sampled HDR color patches. An optimization algorithm is executed to generate an optimized forward reshaping mapping and an optimized backward reshaping mapping. The optimized forward reshaping mapping is used to forward reshape input HDR images into forward reshaped SDR images, whereas the optimized backward reshaping mapping is used to backward reshape the forward reshaped SDR images into backward reshaped HDR images.