Image Density Correction for Printing Inspection Accuracy
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Solution Overview
Problem
Existing printing inspection techniques, such as those described in Japanese Patent Laid-Open No. 2015-178970, cannot accurately inspect output from electrophotographic printing apparatuses when image density variations occur without clear changes, leading to potential defects in printed products.
Innovation Solution
An information processing apparatus that corrects local image density differences in reference images based on global image density variations between reference and printed images, allowing for more accurate defect detection by generating difference data that accounts for permissible uniform image density changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional inspection techniques are used to compare printed image data with reference data, then defect inspection can be performed, but accurate inspection cannot be achieved when global image density variations occur without clear changes
Solution Approach 1:
The patent applies parameter changes by introducing a global density correction parameter that adjusts the reference data to match the actual printing conditions. The system calculates the average density difference across the entire image and uses this parameter to correct local density variations, enabling accurate defect detection even when overall density shifts occur due to printing status changes
Solution Approach 2:
The patent uses an intermediary correction mechanism that acts between the reference data and the printed image data. By introducing a correction unit that calculates and applies density adjustment based on global image density difference, the system mediates the comparison process to account for permissible density variations while still detecting actual defects
2Measurement precision
If strict inspection criteria are applied to detect all potential defects, then defect detection accuracy improves, but false positives increase due to permissible density variations
Solution Approach 1:
The patent applies local quality by differentiating between local defects and global density variations. The correction unit calculates global density difference and applies selective correction to preserve local defect characteristics while removing the effect of global density shifts, enabling the inspection system to tolerate permissible variations while detecting actual local defects
Solution Approach 2:
The system dynamically adjusts the comparison parameters by calculating the global image density difference and using it to modify the reference data. This parameter change allows the inspection to adapt to printing status changes, reducing false positives caused by permissible density variations while maintaining sensitivity to actual defects
Data Source
AI summary
There is provided with an information processing apparatus. A first obtaining unit obtains data of a reference image indicating a target of printing output to be performed by a printing apparatus. A second obtaining unit obtains data of an image printed by the printing apparatus. A correcting unit corrects a local image density difference or the reference image based on a global image density difference between the reference image and the printed image. An evaluating unit evaluates quality of the printed image based on the local image density difference between the corrected reference image and the printed image.