Microscope Image Shading Correction via Flat Area Detection
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Solution Overview
Problem
The existing virtual slide technique for image stitching in microscopy often results in unnatural boundaries and periodic patterns due to uneven brightness caused by shading issues, which are difficult to correct effectively.
Innovation Solution
An image processing device that acquires images from different directions, calculates flatness representing shading gradients, detects a flat area with minimal gradient, and uses a correction gain calculated from this area to correct shading across the image.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If a plurality of images is stitched to generate a virtual slide image, then the field of view is enlarged and the whole specimen is shown, but unnatural boundaries and periodic patterns are generated due to shading
Solution Approach 1:
The patent applies preliminary action by performing shading correction before image stitching. A correction gain map is calculated from reference images captured without a specimen, and this correction is applied to all subsequent specimen images before they are stitched together. This prevents shading-related artifacts from appearing in the final composite image while maintaining the enlarged field of view.
2Manufacturing precision
If shading correction is performed using existing techniques, then brightness uniformity is improved, but complex calibration processes and additional reference image capture are required
Solution Approach 1:
The patent makes the shading correction system universal by capturing reference images using the same imaging path and conditions as specimen images. The correction gain map calculated from these reference images can be applied to multiple different specimens and imaging sessions, eliminating the need for separate calibration procedures for each specimen while achieving brightness uniformity.
3Area of stationary object
If multiple images are captured for stitching, then the coverage area increases, but the accumulation of shading errors increases
Solution Approach 1:
The patent introduces a correction gain map as an intermediary element that mediates between the shading effects of multiple captured images and the final stitched result. This correction map, derived from reference images, serves as a reference standard that is applied to each captured image before stitching, preventing the accumulation of shading errors even as coverage area increases through multiple images.
Data Source
AI summary
An image processing device includes: an image acquisition unit configured to acquire first and second image groups in different first and second directions; a flatness calculation unit configured to calculate first flatness representing a gradient of a shading component in the first direction and calculate second flatness representing a gradient of a shading component in the second direction; a flat area detection unit configured to detect an area, as a flat area, including a position having a minimum gradient of a shading component in an image based on the first and second flatness; and a correction gain calculation unit configured to calculate a correction gain for correcting shading in an image with reference to a correction gain in the flat area by using a luminance ratio in the common area.