Video Color Enhancement Encoding Using Transfer Function Residuals
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Solution Overview
Problem
Current digital imaging systems have limited color bit-depth scalability, with 8-bit color depth being dominant despite advances in capturing and display devices, which hinders the efficient delivery of multimedia content across devices with varying color bit-depth capabilities.
Innovation Solution
The method involves encoding a color enhancement layer differentially by generating a transfer function, such as a look-up table, to map input color values to output color values, and encoding the residual between a conventional and a higher color bit-depth image, allowing for scalable color bit-depth conversion between devices.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If 8-bit color depth is used for compatibility with conventional devices, then device compatibility is improved, but color accuracy and dynamic range are limited
Solution Approach 1:
The video signal is segmented into two layers: a base layer with 8-bit color depth for conventional devices and an enhancement layer with higher bit-depth (e.g., 10-bit or 12-bit) for advanced devices. This segmentation allows each layer to serve different device requirements independently, resolving the contradiction between compatibility and color accuracy.
Solution Approach 2:
The enhancement layer is nested within the base layer structure, where the base layer provides the fundamental 8-bit color information that ensures compatibility, while the enhancement layer contains additional high-precision color data that nested within the same video stream. This nested structure enables low-bit devices to use only the base layer while high-bit devices can utilize both layers for superior color accuracy.
2Measurement precision
If higher color bit-depth is transmitted to all devices, then color accuracy is improved, but data transmission efficiency and storage requirements increase
Solution Approach 1:
Different color precision is applied locally to different device types through the layered structure. The base layer provides sufficient color quality for conventional 8-bit devices, while the enhancement layer provides higher color quality only where needed by advanced devices. This local quality differentiation optimizes data transmission efficiency by avoiding unnecessary high-precision data transmission to devices that cannot utilize it.
Solution Approach 2:
Instead of transmitting full high-bit-depth data to all devices, the patent transmits only the necessary portion (base layer) to conventional devices and adds partial enhancement data only for devices capable of utilizing it. This partial action approach improves transmission efficiency by avoiding excessive data transmission to devices with limited color processing capabilities.
3Productivity
If differential encoding of color enhancement layer is implemented, then coding efficiency is improved, but encoding complexity increases
Solution Approach 1:
The base layer is encoded and processed first, establishing a reference framework for the enhancement layer. This preliminary encoding of the base layer allows the enhancement layer to be encoded differentially relative to it, improving coding efficiency by exploiting the correlation between layers while managing complexity through a structured two-stage encoding process.
Data Source
AI summary
A highly accurate reproduction of visual intensity and contrast rather than the conventional 8-bit color depth is more and more used, motivating the development of an enhanced dynamic range called high bit-depth. A method for encoding a first, low bit-depth image of M bit RGB pixels and a second, high bit-depth video image of N bit RGB pixels, M<N, both having same spatial resolution, comprises generating a first transfer function based on color histograms of the first and the second video image, generating a second transfer function based on the first transfer function, applying the second transfer function to the first video image, wherein a transformed first video image is generated, calculating and encoding the residual, encoding the first video image and transmitting the encoded first video image, the second transfer function and the encoded difference.