Image Sensor Defect Correction via Selective Phase Difference Acquisition
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Solution Overview
Problem
Image capturing apparatuses face challenges in maintaining image quality due to defective pixels, which can degrade image detection accuracy and frame rate, especially when phase difference signals are acquired for focus detection.
Innovation Solution
The apparatus includes a control unit to switch phase difference signal acquisition area-by-area, a correction unit that selects and applies defect information to correct pixel signals, and a memory to store defect information, allowing for efficient defective pixel correction based on changing areas in a frame.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If phase difference signal acquisition is performed for the whole area, then focus detection accuracy is improved, but frame rate decreases
Solution Approach 1:
The image sensing area is divided into multiple regions, and phase difference signal acquisition is selectively performed only in specific regions rather than the entire area. This segmentation allows focus detection to be conducted in targeted zones while other areas maintain normal imaging operations, thereby preserving overall frame rate while achieving sufficient focus detection accuracy.
Solution Approach 2:
Different acquisition strategies are applied to different regions of the image sensor. Regions requiring focus detection undergo phase difference signal acquisition, while other regions perform standard image capture. This local differentiation optimizes resource allocation, ensuring focus detection needs are met without unnecessarily reducing the frame rate for the entire image.
2Reliability
If defective pixel correction is performed using traditional methods, then image quality is maintained, but processing time increases
Solution Approach 1:
Defect information is pre-acquired and stored in memory before actual image capture operations. By preparing correction data in advance, the system eliminates the need for time-consuming defect analysis during real-time processing, thus maintaining image quality while significantly reducing processing time.
Solution Approach 2:
Instead of analyzing and correcting defective pixels in real-time, the system uses pre-generated defect information copies that map defective pixel locations and their correction values. This copying approach allows rapid lookup and application of corrections without repeating complex analysis procedures, preserving image quality while minimizing processing overhead.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach enhances image quality by accurately correcting defective pixels and maintaining high frame rates by selectively applying defect information based on the area of phase difference signal acquisition, thereby improving focus detection accuracy without reducing the number of readable frames.
Implementation Method 1
signal charges of a plurality of pixels arranged in a pixel array each include not only a signal charge which is obtained as a result of a photoelectric conversion of incident light
Data Source
AI summary
In an apparatus, a control unit switches acquisition of a phase difference signal for each area in a sensing device, a correction unit selects defect information associated with a pixel signal acquired from the sensing device and corrects the pixel signal based on the selected defect information, and a memory stores the defect information. The defect information stored in the memory includes at least first defect information and second defect information in the same format as that of the first defect information. The correction unit switches defect information to be used based a change in an area in a frame for which the phase difference signal is to be acquired.