Image Processing Device for Front End Fading Correction
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Solution Overview
Problem
Conventional image processing methods fail to effectively correct front end fading and sweep-up issues in printed images, as they either lead to excessive thinning or inadequate density correction, making it difficult to achieve both thinning and correction simultaneously.
Innovation Solution
An image processing device and method that includes an outline detection unit to analyze image data, a thinning unit to reduce pixel values, and an outline adjusting unit to determine and apply correction values based on the sheet-feeding direction and edge direction, reducing the correction value proportionally to the thinning ratio to correct front end fading and sweep-up.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If thinning processing is applied to reduce pixel values on image outlines, then sharpness of characters is improved, but image density decreases excessively causing outlines to fade or disappear
Solution Approach 1:
The patent applies different processing intensities to different regions of the image. Thinning processing with reduced correction values is applied specifically to outline regions detected by the outline detection unit, while non-outline regions receive standard correction. This local differentiation allows sharpness improvement at outlines without excessive density loss throughout the entire image.
2Manufacturing precision
If correction of front end fading or sweep-up is applied to adjust pixel values on outlines, then image density uniformity is improved, but the thinning effect is reduced or lost
Solution Approach 1:
The patent applies partial correction by reducing the correction value proportionally to the thinning ratio. Instead of applying full correction values that would eliminate the thinning effect, only a portion of the correction is applied to outline pixels. This partial action maintains both the density correction benefit and the sharpness improvement from thinning.
3Measurement precision
If both thinning and correction of front end fading or sweep-up are applied to outer edge pixels, then sharpness and density uniformity are improved, but the correction value becomes excessive causing outlines to fade
Solution Approach 1:
The patent dynamically changes the correction value parameter based on the thinning ratio. The correction value is reduced proportionally to the ratio of pixel value reduction by thinning. This parameter adjustment ensures that the combined effect of thinning and correction achieves both sharpness improvement and density uniformity without excessive correction that would cause outline fading.
Data Source
AI summary
Provided is an image processing device including: an outline detection unit which analyzes image data to detect an outer edge pixel forming the outline of image, and to determine an edge direction of the outer edge pixel; a thinning unit which processes thinning by reducing a pixel value of the outer edge pixel; and an outline adjusting unit. The outline adjusting unit determines a correction value of front end fading to be adopted to the outer edge pixel, depending on sheet-feeding direction when the image data is printed and the edge direction of the outer edge pixel; reduces the correction value of front end fading, depending on the ratio of reduction by the thinning of the pixel value of the outer edge pixel; and corrects the front end fading by adding the reduced correction value to the pixel value of the outer edge pixel.