User-Defined Palette Coding for High-Efficiency Image Compression
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Solution Overview
Problem
The increasing demand for high-resolution and high-quality images leads to a significant increase in transmission and storage costs due to the rise in the amount of transmitted information or bits, necessitating high-efficient image compression technology.
Innovation Solution
An image encoding/decoding method and apparatus that utilizes user-defined palette entries, initializes a palette predictor using adaptation parameter sets, picture parameter sets, or slice headers, and signals these entries through a high-level syntax to enhance encoding/decoding efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If high-resolution and high-quality image data is transmitted, then image quality is improved, but transmission cost and storage cost increase
Solution Approach 1:
The patent changes the parameter representation by introducing a palette-based color space. Instead of transmitting full-resolution color data for each pixel, the system transmits a palette table defining a limited set of colors and represents images using palette indices. This parameter transformation reduces the bit depth required per pixel while maintaining perceptual image quality, directly resolving the contradiction between image quality and transmission volume.
Solution Approach 2:
The patent applies local quality by allowing different regions of the image to reference the same palette table, which is constructed adaptively based on local color characteristics. The palette table provides high-quality color representation where needed, while the index-based encoding reduces transmission data. This localized approach maintains image quality in critical areas while optimizing overall compression efficiency.
2Quantity of substance
If transmission cost is reduced by compressing image data, then storage cost decreases, but image quality may deteriorate
Solution Approach 1:
The patent transforms the color representation parameters from full RGB values per pixel to a compact palette index system. The palette table stores the actual color values, while the image data stores only indices referencing these colors. This parameter change achieves significant compression (reducing transmission data volume) while preserving image quality through the use of perceptually important colors in the palette and smooth gradient approximation.
3Productivity
If a palette table is constructed using conventional methods, then encoding efficiency is improved, but adaptability to user-defined color requirements is limited
Solution Approach 1:
The patent introduces dynamic adaptability by allowing the palette table to be constructed in multiple ways: automatically from image content analysis, manually through user-defined entries, or through a combination of both. The system dynamically selects and merges palette entries based on user requirements and image characteristics, making the encoding process adaptable to different applications while maintaining encoding efficiency through the standardized palette-based framework.
Data Source
AI summary
An image encoding/decoding method and apparatus are provided. An image decoding method according to the present disclosure may include: obtaining palette information and palette index prediction information of a current block from a bitstream; constructing a palette predictor for the current block based on the palette information and constructing a palette table for the current block based on the palette predictor; generating a palette index map for the current block based on the palette index prediction information; and decoding the current block based on the palette table and the palette index map, wherein the palette predictor may be initialized using a user defined palette entry obtained from at least one of an adaptation parameter set (APS), a picture parameter set (PPS) or a slice header.