Invention Grant
US5809177A Hybrid error diffusion pattern shifting reduction using programmable
threshold perturbation
失效
使用可编程阈值扰动的混合误差扩散模式移位减少
- Patent Title: Hybrid error diffusion pattern shifting reduction using programmable threshold perturbation
- Patent Title (中): 使用可编程阈值扰动的混合误差扩散模式移位减少
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Application No.: US660045Application Date: 1996-06-06
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Publication No.: US5809177APublication Date: 1998-09-15
- Inventor: David J. Metcalfe , Jeng-Nan Shiau , Leon C. Williams
- Applicant: David J. Metcalfe , Jeng-Nan Shiau , Leon C. Williams
- Applicant Address: CT Stamford
- Assignee: Xerox Corporation
- Current Assignee: Xerox Corporation
- Current Assignee Address: CT Stamford
- Main IPC: H04N1/405
- IPC: H04N1/405 ; G06K9/36
Abstract:
A process eliminates pattern shifting artifacts in a printed image rendered using a hybrid high addressable error diffusion process by perturbing a threshold/image signal value relationship when a multi-level grey level is binarized. The process utilizes a programmable multi-level grey signal modifying circuit for modifying the multi-level grey signal by a predetermined value according to its grey level. The modified multi-level grey signal is binarized to a binary pixel signal according to a relationship between the modified multi-level grey signal and a threshold value. The process further generates an error corresponding to the relationship and diffuses the error to neighboring pixels. The multi-level grey signal is modified with either random noise multiplied by a grey level dependent coefficient or by a predetermined value from a checkerboard or vertical line pattern. The value from the pattern is dependent upon the grey level and pixel location of the image data.
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