Phase Detection Autofocus Arithmetic Using Interpolated Center Pixel Values
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Solution Overview
Problem
Phase detection autofocus systems using phase difference detection pixels can result in noticeable artifacts in images and are susceptible to errors due to the placement of these pixels, especially when receiving light from opposing sides of image edges, leading to inaccuracies in focus determination.
Innovation Solution
The use of imaging pixels in addition to phase detection pixels for calculating autofocus information, where imaging pixel values are interpolated to determine center pixel values, allowing for the calculation of disparity between center and phase detection pixels, thereby reducing artifacts and improving focus accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If phase detection pixels are spaced apart to reduce artifacts, then image quality improves, but autofocus accuracy deteriorates due to edge light reception errors
Solution Approach 1:
The patent introduces center pixel values as an intermediary element between the spaced phase detection pixels. These center pixel values, derived from imaging pixels, serve as reference points that mediate the autofocus calculation process. By using these intermediary center pixel values in disparity calculations, the system can determine focus accuracy without requiring phase detection pixels to be closely spaced, thus resolving the contradiction between artifact reduction and measurement precision.
2Adaptability or versatility
If phase detection pixels are used in pairs with spacing, then phase difference detection is enabled, but edge location disparities cause calculation inaccuracies
Solution Approach 1:
The patent creates virtual phase detection pixel values by copying and processing imaging pixel data. Instead of relying solely on physical phase detection pixels spaced apart, the system generates virtual equivalents from imaging pixels through interpolation and disparity calculation. These copied virtual values maintain the phase difference detection capability while eliminating the edge location disparity problems associated with physically spaced pixels.
3Object-affected harmful factors
If fewer phase detection pixels are used, then artifacts are reduced, but phase detection capability is weakened
Solution Approach 1:
The patent makes imaging pixels multi-functional by enabling them to serve both as standard imaging pixels and as sources for virtual phase detection pixel values. Through this universal utilization, imaging pixels perform dual functions: capturing image data and providing reference values for autofocus calculations. This eliminates the need for dedicated phase detection pixels, reducing artifacts while maintaining reliable phase detection capability through the versatile imaging pixel array.
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 reduces the need for phase detection pixels, minimizes artifacts in captured images, and enhances the accuracy of autofocus by mitigating disparities caused by edge locations, resulting in a more precise and efficient autofocus process.
Implementation Method 1
a first diode in a pair of phase detection diodes beneath a multi-diode microlens
Data Source
Figure 1A~1C
Figure 2A~2C
Figure 2D
AI summary
Certain aspects relate to systems and techniques for using imaging pixels (that is, non-phase detection pixels) in addition to phase detection pixels for calculating autofocus information. Imaging pixel values can be used to interpolate a value at a phase detection pixel location. The interpolated value and a value received from the phase difference detection pixel can be used to obtain a virtual phase detection pixel value. The interpolated value, value received from the phase difference detection pixel, and the virtual phase detection pixel value can be used to obtain a phase difference detection signal indicating a shift direction (defocus direction) and a shift amount (defocus amount) of image focus.