Line Correction Based on Linked Dot Count
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Solution Overview
Problem
Existing techniques for correcting density fluctuations at the edges of images produced by electrophotographic processes, such as those used in laser beam printers, require significant storage capacity and increased costs due to the need for image data rotation and buffer storage, which complicates the correction process.
Innovation Solution
An image processing apparatus that corrects multivalued data by determining the number of linked dots from the bottom-end edge, reducing storage requirements by converting multivalued data into dot data and using a correction table to adjust the data based on the number of linked dots, thereby minimizing storage needs and costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If image data is held in image memory and arithmetic operations are performed on original image data and translated virtual image data, then edge effect correction is achieved, but storage cost increases significantly
Solution Approach 1:
The invention extracts only the necessary information (edge pixel positions and pixel values in sub scanning direction) from the complete image data, rather than holding and processing all image data. This extraction approach reduces storage requirements while maintaining correction effectiveness.
Solution Approach 2:
Instead of holding original image data and performing arithmetic operations as in conventional methods, the invention inverts the approach by directly detecting edge pixels and using their positions and values to determine correction amounts, eliminating the need for large-scale data storage and complex arithmetic operations on full image data.
2Measurement precision
If 90° rotation is performed to arrange pixel data columns in sub scanning direction for edge pixel detection, then edge pixel detection accuracy is improved, but buffer storage cost increases considerably
Solution Approach 1:
The invention changes the dimension of data access by directly accessing pixel data in the sub scanning direction from the original main scanning direction data structure, without performing physical rotation. This dimensional access change enables accurate edge pixel detection while avoiding the storage overhead of rotated data buffers.
3Manufacturing precision
If complete image data rotation and buffer storage are implemented, then correction processing accuracy is improved, but device complexity increases
Solution Approach 1:
The invention extracts only the critical information needed for correction (edge pixel positions and values) from the complete image data, eliminating the need for complex rotation and buffer management operations while maintaining correction accuracy.
Solution Approach 2:
The invention enables the system to perform correction using readily available pixel data from the image memory without requiring additional complex processing steps such as rotation and buffer management, thereby reducing device complexity while maintaining effectiveness.
Data Source
AI summary
An apparatus that corrects multivalued data after halftone processing and which includes a line input unit configured to input multivalued data of a correction line to be corrected among the multivalued data, a detection unit configured to convert multivalued data of a precedent line that precedes the correction line by N lines into dot data and to detect a dot in the precedent line, and a line correction unit configured to correct the multivalued data of the correction line based on a number of linked dots from the bottom-end edge, and the number of linked detected dots is the number of dots that are linked in a sub scanning direction from the correction line down to the bottom-end edge, and the bottom-end edge is an edge at which the density becomes lower in the sub scanning direction and the lower of density values represents the background color.