Image Sensor Crosstalk Correction Using Focus Pixels
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Solution Overview
Problem
Image quality degradation occurs due to optical crosstalk caused by the microlens of focus detecting pixels in image sensors, which is not effectively addressed by existing techniques that correct crosstalk between image forming and focus detecting pixels.
Innovation Solution
An image capturing apparatus is designed with an image sensor where some image forming pixels are replaced with focus detecting pixels, featuring a comparison unit to compare outputs with adjacent reference image forming pixels and a correction unit to adjust these outputs based on the comparison results, thereby correcting for optical crosstalk.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If focus detecting pixels are arranged in the image sensor, then focus detection function is improved, but image quality degrades due to optical crosstalk
Solution Approach 1:
The patent extracts and removes the harmful optical crosstalk effect from the image sensor output by identifying pixels affected by crosstalk (those adjacent to focus detecting pixels) and correcting their values using reference pixels that are not affected, thereby eliminating the degradation while preserving the focus detection function
Solution Approach 2:
The patent implements a feedback mechanism where the output of focus detecting pixels is used to identify and correct optical crosstalk in adjacent image forming pixels. The correction unit uses the focus detecting pixel outputs as reference information to calculate and apply correction values to affected pixels, creating a closed-loop system that continuously compensates for the harmful effect
2Reliability
If existing correction techniques are used, then some crosstalk is corrected, but optical crosstalk caused by microlens is not effectively addressed
Solution Approach 1:
The patent applies preliminary correction by identifying and correcting optical crosstalk in the image processing pipeline before final image output. The correction unit proactively calculates correction values based on the spatial relationship between focus detecting pixels and image forming pixels, applying the correction in advance to prevent crosstalk from degrading the final image quality
Solution Approach 2:
The patent changes the processing parameters of affected pixels by applying correction values that adjust their output signals. The correction unit modifies the electrical signals from image forming pixels adjacent to focus detecting pixels by adding or subtracting calculated correction amounts, thereby changing the signal parameters to compensate for optical crosstalk effects
Data Source
AI summary
An image capturing apparatus comprises an image sensor constructed by replacing some of a plurality of image forming pixels of the image sensor with focus detecting pixels, a comparison unit configured to compare outputs of the image forming pixels as a plurality of correction targets adjacent to the focus detecting pixel with outputs of a plurality of reference image forming pixels of the same color as the plurality of image forming pixels arranged in the vicinity of the plurality of image forming pixels adjacent to the focus detecting pixel, and a correction unit configured to execute correction processing of the outputs of the image forming pixels as the plurality of correction targets in accordance with a comparison result of the comparison unit.