Image Processing Contour Line Width Consistency
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Solution Overview
Problem
Existing image processing methods struggle to maintain consistent line widths in images with two gradations, especially when formed on different pages, due to periodicity in dither matrices, leading to variations in line widths even if the original widths are the same.
Innovation Solution
An image processing apparatus and method that includes a contour extracting unit, a contour processing unit for reducing gradation values, a dithering unit using a blue noise dither matrix for binarization, and a binarizing unit for non-contour pixels, allowing for high line-width reproducibility by aperiodically dispersing dots in the contour.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If dithering with a periodic dither matrix is used for binarization, then processing speed is improved, but line width consistency deteriorates due to periodicity causing variations depending on line position and orientation
Solution Approach 1:
The patent applies different dither matrices with different periodicities to different regions of the image based on line orientation. Specifically, lines in the main scanning direction use one periodicity, while lines in the sub scanning direction use a different periodicity. This local differentiation ensures that line width consistency is maintained across different orientations while still using efficient dithering for binarization.
Solution Approach 2:
The patent changes the periodicity parameter of the dither matrix based on the orientation of the line being processed. By adjusting the periodicity according to whether the line is in the main or sub scanning direction, the system maintains line width consistency across different orientations while preserving the speed benefits of dithering.
2Manufacturing precision
If error diffusion is used for binarization to achieve aperiodic pattern and consistent line width, then line width consistency is improved, but processing speed deteriorates due to feedback requirements
Solution Approach 1:
The patent segments the binarization process into two distinct paths: one for contour pixels using dithering with orientation-dependent periodicity, and another for non-contour pixels using error diffusion. This segmentation allows the system to use the faster dithering method where possible while maintaining consistency, and only apply the slower error diffusion method where absolutely necessary.
Solution Approach 2:
The patent dynamically selects the binarization method based on the pixel type (contour or non-contour) and line orientation. By making the binarization approach dynamic rather than static, the system optimizes processing speed by using dithering for most pixels while ensuring line width consistency through orientation-adaptive periodicity selection.
Data Source
AI summary
An image processing apparatus includes a contour extracting unit, a contour processing unit, a dithering unit and a binarizing unit. The contour extracting unit extracts a contour pixel forming a contour part from pixels of image data having multiple gradation values. The contour processing unit performs adjustment to reduce a gradation value of the contour pixel extracted by the contour extracting unit. The dithering unit binarizes, by using a blue noise dither matrix, the gradation value of the contour pixel subjected to the adjustment by the contour processing unit. The binarizing unit binarizes, of the pixels of the image data, a gradation value of a non-contour pixel which is other than the contour pixel.