Image Correction Device for Stand Scanners with Non-Uniform Illumination
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Solution Overview
Problem
Stand image scanners face challenges in achieving precise image correction due to non-uniform self-illumination, especially when dealing with large originals and peripheral light interference, leading to inadequate color correction.
Innovation Solution
An image correction device that includes a processor and memory, which controls an image reading apparatus to read images under combined self-illumination and peripheral light, using pre-stored reference charts illuminated by self-illumination and uniform light to correct images, accounting for both light sources.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If white balance correction is performed based on the brightest portion in an image, then color correction can be achieved under uniform self-illumination, but correction precision deteriorates when self-illumination is non-uniform
Solution Approach 1:
The patent segments the illumination into two independent components: self-illumination light from the illumination device and peripheral light from external sources. By separately measuring and correcting for each light source using dedicated measurement regions, the system achieves precise color correction even under non-uniform self-illumination conditions.
Solution Approach 2:
The patent introduces standard color charts as intermediary reference objects placed in specific regions (self-illumination measurement region and peripheral light measurement region). These charts serve as mediators to measure and characterize the color temperature of each light source independently, enabling accurate correction of the original image.
2Illumination intensity
If the lighting device is placed farther away to illuminate the original uniformly, then self-illumination uniformity improves, but the device complexity and space requirements increase
Solution Approach 1:
The patent extracts the peripheral light component from the combined illumination and measures it separately using a dedicated peripheral light measurement region. This allows the system to compensate for non-uniform self-illumination without requiring complex lighting configurations, as the peripheral light effect is isolated and corrected independently.
3Object-affected harmful factors
If a cover is added to stop peripheral light from illuminating the original, then peripheral light interference is reduced, but the device complexity increases
Solution Approach 1:
Instead of physically blocking peripheral light with a cover, the patent uses standard color charts as intermediary measurement objects placed in peripheral light measurement regions. These charts enable the system to measure and correct peripheral light effects without requiring structural modifications to block the light, thus avoiding increased device complexity.
4Measurement precision
If multiple line sensors are used to read images under self-illumination and peripheral light separately, then correction accuracy improves, but the reading time increases
Solution Approach 1:
The patent merges the measurement of self-illumination and peripheral light effects into a single scanning process by using multiple measurement regions within the same image capture. The original image region and standard color chart regions are read simultaneously in one scan, eliminating the need for multiple separate scanning operations and thus reducing reading time while maintaining correction accuracy.
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
Enables precise image correction by considering the effects of both self-illumination and peripheral light, improving color accuracy even with non-uniform illumination, and reduces reading time by allowing a single scan for the original and standard color chart.
Implementation Method 1
an illumination section 22 that illuminates self-illumination light L1 onto a read object P
Implementation Method 2
light reflected from the original is read
Implementation Method 3
a line sensor such as a line CCD provided to the head 82A of the stand 82 is being scanned
Data Source
AI summary
An image correction device includes a processor that executes a procedure. The procedure includes: correcting an image of a read object based on images stored in a storage section of a self-illuminated reference chart image of a reference chart of size corresponding to a mounting region where the read object is mounted that has been read in advance in a state illuminated by only a self-illumination light, a uniform light standard color chart image of a standard color chart that has been read in advance in a state illuminated by only uniform light from a predetermined uniform light source, and a uniform light reference chart image of the reference chart that has been read in advance in a state illuminated by only the uniform light, and based on the image of the read object and a peripheral light standard color chart image read by a reading section.