Flare Correction for Printed Image Inspection Accuracy
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Solution Overview
Problem
Existing inspection techniques for printed images fail to adequately suppress the drop in inspection accuracy caused by the 'flare' effect, which occurs when light reflected from neighboring pixel positions enters the scanner, leading to varying levels of error in image reading.
Innovation Solution
An image-forming system that includes a calibration unit to derive calibration parameters based on referential read image data with flare correction, and an inspection unit that compares calibrated input image data with read image data to inspect the quality of printed images, using weighting coefficients to correct for the flare effect.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a scanner is used to optically read the printed image, then the inspection process is automated and productivity is improved, but flare error occurs when light reflected from neighboring pixel positions enters the reading pixels, causing a drop in measurement precision
Solution Approach 1:
The patent applies flare correction processing that uses the measured flare characteristics (obtained by reading a solid white sheet) to calculate correction values. These correction values are then applied to the read image data to remove the flare effect. This converts the harmful flare phenomenon into a correctable error, allowing automated inspection to maintain high precision despite the presence of flare during the reading process
Solution Approach 2:
The patent changes the parameter of the read image data by applying flare correction values to transform the raw scanned image into a corrected image that compensates for flare effects. This parameter transformation allows the inspection system to maintain measurement precision while using automated optical reading
2Device complexity
If conventional inspection techniques are used without flare correction, then the inspection process is simple and device complexity is low, but inspection accuracy drops due to the flare effect varying from pixel position to pixel position
Solution Approach 1:
The patent performs preliminary flare correction by first reading a solid white sheet to measure the flare characteristics, then calculating correction values before performing the actual inspection. This preliminary action captures the flare profile of the scanning system, which is then used to correct subsequent inspection images, improving precision without significantly increasing operational complexity
Solution Approach 2:
The patent introduces an intermediary flare correction process that acts as a mediator between the raw scanned image and the final inspection result. The correction values serve as an intermediary element that compensates for the flare effect, allowing the system to maintain simplicity while improving measurement precision through this intermediate correction step
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution effectively reduces the impact of flare on inspection accuracy, improving the reliability of printed image quality assessment by dynamically adjusting correction coefficients based on neighboring pixel signal values.
Implementation Method 1
a first obtaining unit configured to obtain an inspection target image by irradiating with light a printed material to be inspected and receiving reflected light from the printed material
Data Source
AI summary
An image-forming unit forms a referential image on a first sheet. A reading unit reads the referential image on the first sheet to generate referential read image data. A calibration unit calibrates input image data using calibration parameters derived based on the referential read image data. The image-forming unit forms a target image on a second sheet based on the calibrated data. The reading unit reads the target image on the second sheet to generate read image data for inspection. An inspection unit inspects quality of the target image based on comparison between the input image data and the read image data for inspection. The calibration parameters are derived based on the referential read image data to which flare correction has been applied. The inspection unit compares the input image data with the corrected read image data.