Selective DCT/DST Image Coding for Lower Bit Rates
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Solution Overview
Problem
Existing image coding technologies, such as H.264/MPEG-4 AVC, face limitations in achieving high compression efficiency due to reliance on block-based motion estimation and transform methods, which do not fully exploit spatial and temporal redundancies in image data.
Innovation Solution
The use of discrete cosine and sine transforms in combination with quantization and threshold operations to generate and select optimal transform coefficients for image blocks, allowing for improved coding efficiency by reducing bit rates and distortion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If block-based motion estimation and transform methods are used, then coding efficiency is improved, but compression efficiency is limited
Solution Approach 1:
The patent applies dynamics by adaptively selecting between DCT and DST transforms based on the characteristics of each image block. The transform type is dynamically chosen according to the block's content properties (e.g., edge presence, texture complexity), allowing the coding system to optimize compression efficiency for diverse image regions rather than using a static transform method throughout.
Solution Approach 2:
The patent changes the transform parameter (selecting between DCT and DST) based on image block characteristics. By analyzing properties such as gradient magnitude and directional features of each block, the system selects the appropriate transform type to maximize energy compaction and minimize residual energy, thereby improving overall compression efficiency while maintaining coding performance.
2Ease of operation
If discrete cosine transform is applied to all image blocks, then coding simplicity is maintained, but compression efficiency is reduced
Solution Approach 1:
The patent applies local quality by using different transform types (DCT or DST) for different image blocks based on their local characteristics. Instead of uniformly applying DCT to all blocks, the system analyzes each block's properties (such as edge orientation and texture) and selects the transform that best suits that local region, thereby improving compression efficiency without significantly complicating the overall coding process.
Solution Approach 2:
The patent introduces dynamic transform selection where the transform type is determined adaptively for each block based on its characteristics. This dynamic approach allows the system to optimize compression for each local region while maintaining a relatively simple coding framework that can be integrated into existing video coding standards.
3Reliability
If transform and quantization are performed on all blocks, then spatial correlation is reduced, but bit rate is increased
Solution Approach 1:
The patent changes the transform parameter selection based on block characteristics to optimize the balance between spatial correlation reduction and bit rate. By selecting DST for blocks with specific properties (such as strong vertical edges) and DCT for others, the system achieves better energy compaction and residual signal characteristics, reducing the number of bits needed to represent the transformed and quantized coefficients while maintaining effective spatial correlation reduction.
Data Source
AI summary
Disclosed is a data transmission system that transmits data by using a relay. The relay selects a transmission terminal from among a plurality of terminals accessing a base station. A base station transmits base station data to the relay during a first time slot, and the transmission terminal transmits terminal data to the relay. The relay transmits terminal data to the base station during a second time slot, and transmits base station data to the transmission terminal.