Imaging Device Aperture-Adaptive Focus Pixel Estimation
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Solution Overview
Problem
Existing imaging devices with image sensors that combine imaging pixels and focus detection pixels suffer from poor image quality due to color artifacts and pattern loss caused by simple averaging methods, which deviate from the actual imaging pixel output when adjusting the aperture.
Innovation Solution
An imaging device with a two-dimensional array of imaging pixels and focus detection pixels, utilizing a coefficient setting circuit to convert focus detection pixel outputs into image outputs based on the aperture value, and estimating circuits to accurately estimate image outputs by processing outputs from surrounding imaging pixels and focus detection pixels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If simple averaging method is used to obtain virtual imaging pixel output from focus detection pixel and surrounding imaging pixels, then device complexity is reduced, but image quality deteriorates due to color artifacts and pattern loss
Solution Approach 1:
The patent applies parameter changes by dynamically adjusting the aperture value of the imaging optical system based on focus detection results. When the subject is out of focus, the aperture is enlarged to increase light flux and improve brightness. This parameter change resolves the contradiction by allowing simple averaging processing to produce acceptable images under specific conditions (out-of-focus states) while maintaining image quality through aperture control rather than complex processing.
2Illumination intensity
If aperture value is changed to improve brightness of captured image, then illumination intensity is improved, but image quality deteriorates due to deviation from actual imaging pixel output
Solution Approach 1:
The patent implements dynamics by making the aperture value adjustable and changeable based on focus detection results. The system dynamically switches between different aperture settings: a smaller aperture for in-focus subjects to maintain image quality, and a larger aperture for out-of-focus subjects to improve brightness. This dynamic adaptation resolves the contradiction by selecting the appropriate aperture value according to the focusing state, thereby improving brightness when needed without sacrificing image quality.
3Device complexity
If focus detection pixels are integrated with imaging pixels on the same substrate, then device complexity is reduced, but measurement precision deteriorates due to inability to accurately estimate imaging pixel output at focus detection positions
Solution Approach 1:
The patent uses an intermediary approach by introducing a conversion coefficient that mediates between the focus detection pixel output and the estimated imaging pixel output. The conversion coefficient, determined based on the aperture value and positional relationships, acts as a bridge to accurately estimate what the imaging pixel output would be at the focus detection pixel position. This intermediary mechanism resolves the contradiction by enabling accurate measurement despite the integrated sensor structure.
Solution Approach 2:
The patent applies preliminary action by pre-calculating and storing conversion coefficients for different aperture values and positional configurations before actual image capture. These coefficients are prepared in advance based on the known geometric relationships and optical characteristics, allowing rapid and accurate estimation of imaging pixel outputs during focus detection without real-time complex calculations, thereby maintaining measurement precision in the integrated sensor structure.
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 solution effectively prevents color artifacts and pattern loss, ensuring high-quality image capture by accurately estimating image outputs at focus detection pixels, even when the aperture is adjusted.
Implementation Method 1
an image sensor that includes imaging pixels that are disposed in a two-dimensional array and focus detection pixels disposed in part of the array of the imaging pixels
Data Source
AI summary
An imaging device includes an image sensor that includes imaging pixels that are disposed in a two-dimensional array and focus detection pixels disposed in part of the array of the imaging pixels, a coefficient setting circuit that sets a conversion coefficient to be used to convert an output from each focus detection pixel to an image output at the focus detection pixel, in correspondence to an aperture value set at an imaging optical system, and an estimating circuit that estimates the image output at the focus detection pixel based upon the conversion coefficient and the output from the focus detection pixel.