Image Processing Contour Correction for Oblique Line Jaggy
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Solution Overview
Problem
Inkjet recording apparatuses face image quality deterioration due to jaggy corrections when printing images with different resolutions in the main-scanning and sub-scanning directions, leading to unwanted bumps or white spots in oblique lines.
Innovation Solution
An image processing method that performs contour portion correction by adding or deleting dots at specific pixels adjacent to step-like contour portions, based on the angle and thickness of the oblique line, to maintain image quality without creating adverse effects like bumps or white spots.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a small dot is added at a correction target pixel to correct jaggy, then the jaggy is reduced, but the image portion becomes fattened and thickness of character or line changes causing bump-like lumps
Solution Approach 1:
The patent applies different processing to different local regions: when a dot is present at an adjacent pixel, the correction target pixel is set to 0 (no addition), but when no dot is present, the correction target pixel is set to 1 (dot addition). This local differentiation prevents uniform fattening while maintaining contour smoothness where needed.
Solution Approach 2:
Instead of always adding dots to correct jaggy, the patent inverts the approach by conditionally adding dots only when adjacent pixels don't already have dots. This inversion prevents the harmful effect of always adding dots while preserving the beneficial jaggy correction effect where applicable.
2Reliability
If dot size is set based on the direction of lower resolution to prevent white spots, then white spots are prevented, but the dot size is too large in the direction of higher resolution causing jaggy correction to deteriorate
Solution Approach 1:
The patent applies different dot sizes to different directional regions. In the main-scanning direction (lower resolution), larger dots are used to prevent white spots, while in the sub-scanning direction (higher resolution), smaller dots are used to maintain oblique line quality. This local differentiation resolves the contradiction between preventing white spots and maintaining line quality.
3Manufacturing precision
If dot addition is performed at correction target pixels, then jaggy is corrected, but unwanted lumps or white spots appear in oblique lines
Solution Approach 1:
The patent performs preliminary checking of adjacent pixels before adding dots at correction target pixels. By checking whether adjacent pixels already contain dots and conditionally preventing dot addition based on this information, the patent prevents the formation of lumps and white spots before they occur, rather than attempting to correct them afterward.
Solution Approach 2:
The patent performs preliminary analysis of the dot pattern in adjacent pixels before executing the jaggy correction. This preliminary action allows the system to predict where dot addition might cause harmful artifacts and adjust the correction strategy accordingly, preventing artifacts before they manifest in the final image.
Data Source
AI summary
An image processing method generates image data of an image made up of a plurality of dots and having resolution in a first direction and resolution in a second direction. The second direction intersects the first direction. The resolution in the first direction is different from the resolution in the second direction. The image processing method includes performing contour portion correction including adding a dot at a correction target pixel, the correction target pixel being a pixel adjacent to a step-like contour portion in the image, and when a dot is arranged at a pixel adjacent to a pixel of interest adjacent to the correction target pixel, deleting the dot at the pixel of interest.