Geometric Distortion Compensation in Printing Systems
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Solution Overview
Problem
Existing printing systems face challenges in aligning compensation data with non-uniformities in scanned images, leading to misalignment of streak reduction compensation, particularly due to differences in magnification factors used during uniformity calibration and application, which results in streak defects in printed images.
Innovation Solution
A computer-implemented method and system that acquire uniformity data for scanned pages, spatially scale tone reproduction curves (TRCs) based on geometric distortion parameters, and apply the scaled compensation data to ensure alignment with non-uniformities, using a processor to execute instructions for compensating non-uniformities in printed images.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If uniformity data is acquired with one electronic registration magnification factor but applied at another, then the streak reduction compensation can be misaligned with the marking process, but using different magnification factors allows adaptation to different printing conditions
Solution Approach 1:
The system automatically determines and applies the appropriate electronic registration magnification factor when acquiring uniformity data. By changing the magnification parameter to match the actual printing conditions, the system ensures that compensation data is acquired and applied consistently, eliminating misalignment while maintaining adaptability to different printing scenarios.
2Shape
If image is scaled up to compensate for paper shrinkage, then the image can be returned to nominal size, but the uniformity compensation applied to each pixel column becomes misaligned with corresponding physical columns in the marking process
Solution Approach 1:
The system performs preliminary scaling of the uniformity compensation data by the inverse of the electronic registration magnification factor before applying it to the image. This preliminary action ensures that the compensation data is pre-adjusted to match the scaled image dimensions, maintaining alignment between compensation columns and physical marking columns even after image scaling for paper shrinkage compensation.
3Object-generated harmful factors
If streak reduction algorithms are used at 600 spi, then streak reduction can be achieved, but optimal image quality requires VCSEL ROS with 2400 spi output
Solution Approach 1:
The system automatically determines the appropriate electronic registration magnification factor based on the scanning and printing conditions. By dynamically adjusting this parameter, the system enables streak reduction algorithms to function effectively at lower resolutions (600 spi) while maintaining the ability to achieve optimal image quality at higher resolutions (2400 spi) when needed, thus resolving the contradiction between streak reduction capability and image quality optimization.
Data Source
AI summary
As set forth herein, computer-implemented methods and systems facilitate detecting non-uniformities (e.g., streaks or other defects) in a scanned image, and correcting the non-uniformities while accounting for geometric distortion therein. For instance a scanned image may include a light streak (e.g., higher L* values than expected) down the page at a given distance from a page edge. Paper shrinkage may also cause the image to be magnified relative to the page. Correction values (e.g., L* knockdown values or the like) are generated to bring the non-uniform L* values down to a darker level. To account for the magnification of the image, the correction values are electronically registered to uniformity data for the page, and applied at the correct location to account for the magnification. The corrected image is then printed by a marking device.