Image Processing Apparatus for Print Defect Detection
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Solution Overview
Problem
Existing image processing methods for inspecting printed materials face challenges in accurately detecting print defects due to print position displacement, which affects the stability of paper white detection and brightness correction, leading to deteriorated inspection accuracy.
Innovation Solution
An image processing apparatus that acquires reference and target images, corrects the target image by matching paper white areas based on positional displacement, and inspects the printing result by comparing the corrected images, using a paper white detection range determined by print position displacement information to stabilize paper white detection and improve defect detection accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If paper white detection is performed using fixed coordinate positions in margin areas, then the detection process is simple, but print position displacement causes unstable detection results and deteriorated inspection accuracy
Solution Approach 1:
The patent applies dynamics by transitioning from fixed coordinate positions to dynamic search regions for paper white detection. Instead of using predetermined fixed coordinates that become unreliable due to print position displacement, the system dynamically determines search regions based on actual print position information, allowing the detection coordinates to adapt and move with the print displacement, thereby maintaining both operational simplicity and detection accuracy
Solution Approach 2:
The patent changes the parameter of detection coordinate positions from fixed values to variable values that depend on print position displacement. By using print position information to adjust the search region coordinates dynamically, the system maintains accurate paper white detection despite variations in print positioning, resolving the contradiction between simple fixed-coordinate detection and accurate variable-coordinate detection
2Productivity
If brightness correction is performed using paper white from fixed coordinate positions, then the correction process is fast, but print position displacement leads to inappropriate correction and reduced defect detection accuracy
Solution Approach 1:
The patent makes the brightness correction process dynamic by using print position-dependent search regions instead of fixed coordinate positions. The system quickly determines the appropriate search region based on print position information and extracts paper white values from the correct locations, maintaining both fast correction speed and accurate defect detection by adapting to print position variations
Solution Approach 2:
The patent applies preliminary action by using print position information to pre-determine the search region for paper white detection before performing brightness correction. This preliminary determination of the correct search area based on expected print position allows the subsequent brightness correction to be both fast and accurate, as the correct paper white values are identified in advance
3Ease of operation
If margin area is used for paper white detection, then the area is easily identifiable, but print position displacement varies the margin area and destabilizes paper white detection
Solution Approach 1:
The patent changes the parameter of the search region from a fixed margin area to a dynamic region defined by print position information. Instead of relying on fixed margin coordinates that become unreliable with print displacement, the system adjusts the search region parameters based on actual print position, maintaining both the ease of identifying the paper white area and the stability of detection results
Data Source
AI summary
An image processing apparatus includes an acquisition unit configured to acquire a reference image serving as a reference printing result and a target image serving as a printing result to be inspected, a correction unit configured to correct the target image based on a paper white area of each of the reference image and the target image so that a paper white color of the paper white area of the target image matches a paper white color of the paper white area of the reference image, wherein the paper white area is determined based on a positional displacement between the reference image and the target image, and an inspection unit configured to inspect the printing result by comparing the corrected target image with the reference image.