Shading Correction Circuit for Triple-CCD Imaging
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Solution Overview
Problem
Existing imaging apparatuses using triple-CCD or triple-CMOS sensors face challenges in correcting color shading caused by varying ambient light quantities, particularly in marginal areas, where signal levels differ for each color component, and require large memory capacity for correction.
Innovation Solution
An imaging apparatus with a shading correction module that calculates the shading level using the square of the address distance from the center of the screen for each pixel, defining a correction area between two circles and applying correction values based on 'Size', 'Gain', and 'Position' parameters to adjust the light quantity, thereby reducing memory requirements and preventing overcorrection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If shading correction is applied to all areas of the image, then color shading is corrected, but memory capacity requirements increase and overcorrection occurs in central areas
Solution Approach 1:
The image area is segmented into two distinct regions: a central area (first region) where shading correction is not applied, and a marginal area (second region) where shading correction is applied. This segmentation allows the system to avoid overcorrection in the central area while still correcting color shading in the marginal area, thereby reducing memory capacity requirements by only storing correction data for the necessary region.
Solution Approach 2:
Different correction strategies are applied to different regions of the image. The central area receives no shading correction to prevent overcorrection and color unevenness, while the marginal area receives full shading correction to eliminate color shading. This local differentiation optimizes both correction accuracy and memory efficiency.
2Manufacturing precision
If shading correction is applied uniformly across the image, then light quantity is corrected, but color unevenness occurs in the central area
Solution Approach 1:
The image is divided into a central first region and a marginal second region. By excluding the central region from shading correction, the system prevents the color unevenness that would otherwise occur from overcorrection, while still applying correction to the marginal region where color shading is present.
Solution Approach 2:
The correction approach is localized to only where needed - the marginal area. The central area maintains its original characteristics without correction, ensuring color uniformity is preserved where it already exists, while correction is applied only to the marginal area where color shading problems occur.
3Manufacturing precision
If correction data is stored for the entire image, then comprehensive correction is achieved, but memory capacity requirements increase
Solution Approach 1:
Correction data is stored only for the second region (marginal area) where shading correction is needed, rather than for the entire image. This segmentation of the correction data storage to match the segmented correction application areas significantly reduces memory capacity requirements while maintaining comprehensive correction coverage where actually needed.
Solution Approach 2:
The unnecessary correction data for the first region (central area) is extracted and removed from the correction data set. Since no correction is applied to the central area, storing correction data for this region would be wasteful. By taking out this unnecessary data, memory capacity is reduced without compromising correction effectiveness in the marginal area.
Data Source
AI summary
According to one embodiment, a shading correction circuit, which corrects for the influence of ambient light quantity shading, for input image light from three CCD sensors of R, G and B, based on a distance from the center of a screen. A shading correction circuit does not make correction for a maximum correction area which is out of a circle with a distance a from the central part of a screen, and corrects for the influence of ambient light quantity shading for a minimum correction area with a distance b from the central part of a screen, after calculating a square L2 of an address distance of each pixel of a correction object obtained by using a vertical distance and a horizontal distance from an address of the central part of a screen.