Error Diffusion Image Processing Region Boundary Quality
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Solution Overview
Problem
Error diffusion processing in image halftoning leads to image quality degradation at the boundaries of divided regions due to discontinuity in error diffusion, resulting in dot pattern mismatches and increased memory and calculation costs.
Innovation Solution
Implementing error diffusion processing by scanning pixels in both perpendicular directions within each region, using diffusion coefficients to approximate and compensate for quantization errors across region boundaries, and storing errors in separate memory areas to maintain continuity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If an image is divided into a plurality of regions and halftone processing is performed using the error diffusion method, then the storage capacity of memory is reduced, but image quality degrades at the boundary between regions due to discontinuity in error diffusion
Solution Approach 1:
The image is divided into a plurality of regions, and error diffusion processing is performed for each region separately. This segmentation allows the storage capacity of memory to be reduced while maintaining the ability to process large images. The patent applies this by dividing the image into regions that can be processed independently with limited memory resources.
Solution Approach 2:
An overlapping region is introduced between adjacent regions to serve as an intermediary for error diffusion continuity. The overlapping region contains pixels that belong to both adjacent regions, allowing error diffusion to continue smoothly across region boundaries. This intermediary structure prevents dot pattern mismatch and maintains image quality at boundaries.
2Manufacturing precision
If an overlapping region is set for error diffusion processing near the boundary, then continuity of error diffusion is maintained, but memory capacity and calculation amount increase
Solution Approach 1:
The overlapping region is applied locally only at the boundaries between regions, rather than throughout the entire image. This local application maintains error diffusion continuity where it is most needed (at boundaries) while minimizing the additional memory capacity and calculation amount required. The majority of the image is processed without overlapping, reducing overall resource requirements.
3Device complexity
If error diffusion processing is performed by scanning pixels in one direction, then processing is simplified, but dot pattern mismatch occurs at region boundaries due to one-sided error diffusion
Solution Approach 1:
Error diffusion processing is performed by alternately scanning pixels in upward and downward directions in a periodic manner. This periodic bidirectional scanning prevents one-sided error diffusion and the resulting dot pattern mismatch at region boundaries. The scanning direction alternates between adjacent lines, ensuring that error diffusion occurs in both directions and maintaining image quality without significantly increasing processing complexity.
Data Source
AI summary
Error diffusion processing is performed for each pixel in each region of an image divided into a plurality of regions, by scanning in both the first and second directions different to each other. A diffusion coefficient set for diffusing, to the pixel of interest to be processed, a quantization error generated upon quantizing a pixel near the pixel of interest is set in accordance with the position of the pixel of interest in scanning in the first direction in the region of interest. The pixel of interest to which an error has been diffused from a pixel position referring to the set diffusion coefficient set is quantized.