Phase Difference Pixel Focus Control for Moving Objects
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Solution Overview
Problem
Mirror-less cameras face challenges in capturing high-speed continuous images of moving objects due to the need for live-view image display for focus detection using image plane phase difference AF, limiting their ability to predict and focus on moving objects quickly.
Innovation Solution
A digital image processing apparatus with a control unit that performs focus detection on still images captured during previous operations, determines object movement speed, and corrects the focus location of the focusing lens, allowing for high-speed continuous image capture without relying on live-view image output.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If phase difference detection is performed using live-view image display, then focus detection is enabled, but continuous image capture speed is limited
Solution Approach 1:
The patent performs focus detection using phase difference detecting pixels during the exposure period of still image capture, before the image is fully processed and displayed. This preliminary focus detection allows the system to prepare focus information in advance, enabling faster continuous capture by eliminating the need to wait for live-view display completion before performing focus measurements.
Solution Approach 2:
The patent extracts phase difference information directly from the captured still image data using dedicated phase difference detecting pixels, separating the focus detection function from the live-view display function. This extraction allows focus detection to occur independently during image capture without being constrained by the live-view display timing, thereby improving continuous capture speed.
2Manufacturing precision
If all pixels are output for still image capture, then image quality is improved, but processing time increases
Solution Approach 1:
The patent segments the pixel array into imaging pixels for full-image capture and phase difference detecting pixels for focus measurement. By dedicating specific pixels to phase difference detection, the system can perform focus detection using only those segmented pixels during exposure, reducing the processing burden compared to analyzing all pixels, while still maintaining full-resolution image quality output.
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
Enables continuous image capture of moving objects at high speeds by predicting object motion and correcting focus location based on previous focus detection results, improving the camera's ability to maintain focus during rapid object movement.
Implementation Method 1
phase difference detecting pixels for detecting phase difference of a captured image
Data Source
Figure 1A
Figure 1B~2
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AI summary
A digital image processing apparatus and a method of controlling the same are provided. The method of controlling an image plane phase difference digital image processing apparatus, the method includes, in a continuous photographing mode for continuously capturing still images, performing a first focus detection by detecting phase difference of an image captured during a first image capture; performing a second focus detection by detecting phase difference of an image captured during a second image capture; determining moving speed of an object based on results of the first focus detection and the second focus detection; and correcting focus location by driving a focusing lens based on the determined moving speed of the object.