Image Encoding Tile Quantization for Boundary Distortion Control
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Solution Overview
Problem
Existing image encoding techniques, such as JPEG 2000, face challenges in reducing tile boundary distortion and achieving high code amount controllability while maintaining simplicity and avoiding increased implementation complexity.
Innovation Solution
An image encoding apparatus that divides image data into tiles and applies either uniform or individually set quantization parameters across sub-bands, dynamically switching between these methods based on target data amount to minimize distortion and optimize code control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If independent quantization is executed for each tile to increase concurrency level and reduce RAM capacity, then processing efficiency is improved, but tile boundary distortion occurs due to differences in quantization errors
Solution Approach 1:
The patent applies different quantization parameter settings to different regions: identical quantization parameters are used within each tile to maintain local consistency and reduce boundary distortion, while allowing different tiles to have different quantization parameters to maintain processing efficiency and reduce memory requirements
Solution Approach 2:
The image is divided into multiple tiles that can be processed independently and in parallel. Each tile is processed separately through the wavelet transform and quantization stages, enabling concurrent processing while maintaining overall image quality through controlled boundary transitions
2Manufacturing precision
If the same quantization parameter is applied to all tiles to eliminate boundary distortion, then image quality is improved, but code amount controllability deteriorates
Solution Approach 1:
The patent dynamically adjusts quantization parameters based on the target code amount requirements. The quantization parameters are not fixed but are adaptively selected to meet the desired code rate while maintaining acceptable image quality and minimizing boundary distortion effects
3Manufacturing precision
If error data encoding processing units are added to reduce boundary distortion as in prior art, then boundary distortion is reduced, but device complexity increases
Solution Approach 1:
The patent extracts and eliminates the need for complex error data encoding and decoding units by using a simpler approach: applying identical quantization parameters within tiles during the encoding process itself, thereby achieving boundary distortion reduction without adding separate error correction hardware or software modules
Data Source
AI summary
An apparatus comprises a dividing unit which divides image data to be encoded into a plurality of tiles, a converting unit which generates a plurality of sub-bands by a frequency transform on the divided tiles, a quantizing unit which quantizes the generated sub-bands by either (1) a first method of quantizing by identical quantization parameters in relation to identical sub-bands of a plurality of tiles, or (2) a second method of quantizing by quantization parameters set individually for each tile in relation to identical sub-bands of a plurality of tiles, an encoding unit which encodes data obtained by the quantizing, and a control unit which switches, in accordance with a target data amount of the image data to be encoded, whether to quantize by the first method or to quantize by the second method.