Low-Density Phase Detection Camera Focus with Image Interpolation
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Solution Overview
Problem
Existing autofocus technologies in cameras with low-density phase detection (PD) pixels face a trade-off between autofocus performance and image quality, as reducing PD pixels for better image quality decreases phase detection information, while increasing PD pixels degrades autofocus performance.
Innovation Solution
A method involving generating two channel images by interpolating PD pixel values using adjacent image pixel values and using a focus determination model to determine the lens position, which incorporates both PD pixel and image pixel values to enhance autofocus performance in cameras with low PD pixel density.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If PD pixel density is reduced to improve image quality, then image quality is improved, but autofocus performance deteriorates due to insufficient phase detection information
Solution Approach 1:
The patent introduces image pixel values as an intermediary element to supplement the insufficient PD pixel values. By using image pixels adjacent to PD pixels as mediators to infer phase difference information, the system compensates for the low density of PD pixels while maintaining both image quality and autofocus performance.
Solution Approach 2:
The patent changes the parameter utilization approach by not only relying on PD pixel values but also incorporating image pixel values into the focus determination process. This parameter expansion allows the system to maintain autofocus accuracy even with reduced PD pixel density by leveraging additional visual information.
2Measurement precision
If PD pixel density is increased to improve autofocus performance, then autofocus performance is improved, but image quality deteriorates due to reduced light collection area
Solution Approach 1:
The patent applies partial action by using only the necessary PD pixel values for focus detection while leaving other pixels as image pixels. Instead of requiring high density of PD pixels throughout the entire sensor, the system strategically uses a subset of PD pixels combined with image pixel interpolation to achieve sufficient autofocus performance without sacrificing image quality.
3Adaptability or versatility
If PD pixels are used for phase detection, then autofocus capability is enabled, but the number of pixels available for image capture is reduced
Solution Approach 1:
The patent implements multi-functionality by enabling image pixels to serve dual purposes: they function as both image capture pixels and as supplementary phase detection references. By using image pixels adjacent to PD pixels for interpolation-based focus estimation, the system allows image pixels to contribute to autofocus while maintaining their primary image capture function.
Data Source
AI summary
A processor-implemented method includes obtaining an image comprising a target object, generating, from the image, a first channel image comprising first phase detection (PD) pixel values and a second channel image comprising second PD pixel values, determining a position of a lens to focus on the target object based on a focus determination model to which the first channel image and the second channel image are input, and controlling a camera according to the position of the lens, wherein the first channel image and the second channel image each comprise PD pixel values for detecting a phase difference in the image, and image pixel values comprising information on the image.