Video Coding Interpolation Encoding Smooth Regions
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Traditional video codecs face issues with artefacts such as blockiness and ringing, especially when coarse quantization of DCT coefficients is used, particularly in areas with gradual pixel value changes like human faces and skies, leading to visually unpleasant decoded images.
Innovation Solution
The solution involves omitting spatial prediction and DCT transform operations for selected areas of the image and using interpolation to generate pixel values, defining a spatial surface with minimal discontinuities, and scanning image blocks in a left-to-right, up-to-down order to efficiently encode and decode images, even with coarse quantization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If coarse quantization of DCT coefficients is used to reduce file size or transmission bit rate, then compression efficiency is improved, but visual quality deteriorates due to artefacts like blockiness and ringing
Solution Approach 1:
The patent applies different encoding strategies to different regions of the image based on their characteristics. Smooth regions (like skies and human faces) use interpolation-based encoding to avoid quantization artefacts, while other regions use traditional DCT-based encoding. This local differentiation allows coarse quantization in appropriate areas without degrading overall visual quality.
Solution Approach 2:
The patent changes the encoding parameter from traditional DCT coefficients to interpolated pixel values for smooth regions. By detecting smooth areas and switching to an interpolation-based reconstruction method, the system avoids the quantization artefacts inherent in DCT while maintaining compression efficiency.
2Stability of the object's composition
If traditional spatial prediction and DCT transform operations are applied to all image blocks, then encoding consistency is maintained, but computational complexity and processing time increase
Solution Approach 1:
The patent segments the image into smooth regions and non-smooth regions, applying different encoding methods to each. Smooth regions use interpolation-based encoding while other regions use traditional DCT encoding. This segmentation reduces overall computational complexity by avoiding unnecessary DCT operations in smooth areas.
Solution Approach 2:
Instead of applying full DCT transform to all blocks, the patent applies DCT only where necessary (non-smooth regions). For smooth regions, a simpler interpolation method suffices, reducing computational effort while maintaining adequate encoding consistency through adaptive method selection.
3Loss of information
If DCT transform is applied to blocks with gradual pixel value changes, then frequency information is captured, but ringing artefacts are generated in the decoded image
Solution Approach 1:
The patent identifies smooth regions where DCT would cause ringing artefacts and applies an alternative interpolation-based method instead. By detecting the presence of gradual pixel changes, the system converts a potentially harmful operation (DCT on smooth regions) into a beneficial alternative (interpolation) that preserves the gradual transitions without introducing artefacts.
Data Source
Figure 1~2
Figure 3
Figure 4a
AI summary
There is disclosed an apparatus, a method and a computer program for video coding. The apparatus comprises a selector configured for selecting an encoding method from a set of encoding methods comprising at least a first encoding method and a second encoding method for encoding a block of pixels of an image. The selector is further configured for selecting at least one control point among the pixels of said block of pixels; and selecting a first reference point different from said control point. The apparatus further comprises a determinator configured for determining values of the other pixels of said selected block of pixels on the basis of the value of said control point and the value of said at least one reference point.