White Spot Correction Circuit for Endoscope Image Pickup
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Solution Overview
Problem
Image pickup devices used in endoscope apparatuses often have defective pixels and noise, which existing technologies struggle to correct effectively, leading to suboptimal image quality due to blunted waveforms and ringing phenomena caused by cable transmission.
Innovation Solution
An image pickup apparatus that includes a white spot correction circuit, which calculates correction values based on positional information of defective pixels and peripheral pixel signals, excluding adjacent pixel signals to correct defective pixel signals and address ringing issues, thereby improving image quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If interpolation is performed using peripheral pixels including adjacent pixels, then correction can be applied to defective pixels, but ringing artifacts are generated due to cable transmission effects
Solution Approach 1:
The patent extracts and excludes the adjacent pixel signal from the interpolation calculation. By removing the signal from the pixel immediately adjacent to the defective pixel, the invention eliminates the source of ringing artifacts while still allowing correction of the defective pixel using the remaining peripheral pixels.
Solution Approach 2:
The patent applies different treatment to different peripheral pixels based on their position relative to the defective pixel. Adjacent pixels are excluded from interpolation to avoid ringing, while other peripheral pixels are included to provide correction data, creating a non-uniform approach to pixel utilization.
2Productivity
If all peripheral pixels are used for correction calculation, then correction effectiveness is improved, but image quality deteriorates due to blunted waveforms and ringing
Solution Approach 1:
The invention extracts and removes the adjacent pixel signal from the set of peripheral pixels used in correction calculation. This selective exclusion prevents the propagation of waveform blunting and ringing artifacts while maintaining correction effectiveness through the remaining peripheral pixels.
Solution Approach 2:
The patent converts the harmful effect of cable transmission (which causes ringing and waveform blunting) into a benefit by using the exclusion of adjacent pixels as a deliberate correction strategy. The harmful transmission effects are counteracted by intentionally excluding the adjacent pixel that would otherwise propagate these artifacts.
Data Source
AI summary
An image pickup apparatus includes: an image pickup device that outputs pixel signals picked up by a plurality of pixels arranged in a two-dimensional manner for picking up an image of an object; a white spot positional information storage portion that stores positional information of a white-spot pixel that exists in the image pickup device; an image pickup device drive portion; and a white spot correction portion that, based on positional information of the white-spot pixel that is read out from the white spot positional information storage portion, performs correction with respect to the pixel signal of the pixel that is determined to be the white-spot pixel based on a white spot correction value calculated based on seven pixels that surround a pixel that is determined to be the white-spot pixel.