Focus Detection Pixel Interpolation Shift Correction
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Solution Overview
Problem
Existing image pickup apparatuses face challenges in achieving highly accurate focus detection while minimizing image degradation, as sparsely arranged focus detection pixels can degrade sampling characteristics and interpolation methods may cause partial image degradation.
Innovation Solution
The apparatus includes a detection unit that calculates first and second phase differences based on output signals from image pickup and focus detection pixels, using a control unit to control focusing and correct image shift amounts to improve focus detection accuracy without degrading the image.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If focus detection pixels are sparsely arranged to reduce image degradation, then image degradation is reduced, but sampling characteristics of focus detection image are degraded
Solution Approach 1:
The image pickup element is divided into two distinct pixel types: focus detection pixels for phase difference measurement and image pickup pixels for capturing image information. This segmentation allows each pixel type to be optimized for its specific function, with focus detection pixels arranged to achieve both sparse distribution (reducing image degradation) and adequate sampling (maintaining focus detection performance).
Solution Approach 2:
The image pickup pixels serve dual purposes: they capture image information for the final image and also provide data for interpolation calculations to generate pixel signals at focus detection pixel positions. This multi-functionality allows the system to maintain focus detection accuracy without requiring all pixels to be dedicated focus detection pixels, thereby reducing image degradation.
2Measurement precision
If focus detection pixels are densely arranged to improve sampling characteristics, then focus detection performance is improved, but image degradation occurs due to interpolation processing
Solution Approach 1:
Instead of using actual image pickup pixels at focus detection pixel positions (which would cause interpolation degradation), the system creates virtual copies of the required pixel signals through interpolation calculations using data from real image pickup pixels. This copying approach maintains the necessary sampling characteristics for focus detection while avoiding the direct interpolation of focus detection pixel signals that causes image degradation.
3Measurement precision
If interpolation processing is performed to generate pixel signals at focus detection pixel positions, then sampling characteristics are improved, but partial image degradation occurs
Solution Approach 1:
The patent extracts only the necessary image information from image pickup pixels that is required for interpolation calculations at focus detection pixel positions. By selectively using only the minimal required data from image pickup pixels for interpolation, the system improves sampling characteristics while minimizing the impact on image quality, as not all image pickup pixel data is compromised by the interpolation process.
Data Source
AI summary
A detection apparatus configured to detect a focus state based on an output signal from an image pickup element capable of outputting an image pickup signal and a phase-difference detection signal includes, a first calculation unit configured to calculate information related to a first phase difference based on the phase-difference detection signal output from the image pickup element, a second calculation unit configured to calculate information related to a second phase difference based on the image pickup signal output from the image pickup element, and a detection unit configured to detect the focus state based on the information related to the first phase difference and the second phase difference.