Image Block Color Space Conversion for Quantization Control
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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 device that utilizes selective color space conversion, including determining quantization parameters and transform coefficients based on color space conversion, with clipping to enhance encoding/decoding efficiency, and a method for transmitting and storing bitstreams generated by this process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If color space conversion is applied to all blocks, then encoding/decoding efficiency is improved, but processing complexity and time increase
Solution Approach 1:
The image is divided into blocks, and color space conversion is selectively applied only to blocks where it is beneficial (e.g., blocks with certain characteristics or in certain regions), rather than applying it uniformly to all blocks. This segmentation approach improves efficiency where needed while reducing unnecessary processing elsewhere.
Solution Approach 2:
Instead of applying color space conversion to all blocks (excessive action), the patent applies it partially only to selected blocks where it provides the most benefit. This partial action reduces overall processing time while maintaining encoding/decoding efficiency for the most critical regions.
2Reliability
If quantization parameter clipping is applied, then robustness of quantization parameter values is improved, but flexibility in parameter selection is reduced
Solution Approach 1:
The quantization parameter clipping mechanism preemptively prevents extreme or invalid parameter values from causing problems during encoding/decoding. By establishing upper and lower limits in advance, the system avoids potential issues with out-of-range parameters while still allowing flexible selection within the acceptable range.
Solution Approach 2:
The patent modifies the quantization parameter by applying clipping operations that change the parameter values to fall within acceptable ranges. This parameter change approach ensures robustness by eliminating invalid values while maintaining flexibility through controlled adjustment within the clipped range.
3Loss of time
If selective color space conversion is performed, then processing time is reduced, but encoding/decoding efficiency may deteriorate
Solution Approach 1:
The patent applies different processing qualities to different regions. Color space conversion is applied selectively based on local characteristics of each block, such as whether the block contains important visual information or can be processed more efficiently without conversion. This local quality approach optimizes the balance between processing time and efficiency.
Data Source
AI summary
Provided are an image encoding/decoding method and device. An image decoding method performed by an image decoding device according to the present disclosure includes the steps of: determining a quantization parameter of the current block on the basis of whether color space conversion is applied to a residual sample of the current block; determining a transform coefficient of the current block on the basis of the quantization parameter; determining the residual sample of the current block by using the transform coefficient; and resetting the value of the residual sample on the basis of whether the color space conversion is applied.