Signal Processing for Image Pickup Saturation Correction
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Solution Overview
Problem
Existing image pickup apparatuses struggle with highly accurate focus detection when pixels are saturated, as they cannot effectively handle the saturation characteristics of multiple pixels sharing a microlens, leading to inaccurate image signals.
Innovation Solution
A signal processing apparatus that includes a saturation detector and an estimating portion to identify and correct saturated pixels by using nearby pixels with different saturation characteristics, allowing for accurate charge amount estimation and improved focus detection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If multiple pixels share one microlens for focus detection, then focus detection capability is improved, but measurement precision deteriorates when pixels are saturated
Solution Approach 1:
The pixels sharing a microlens are divided into two groups with different saturation characteristics. By segmenting the pixel functionality, the system can use non-saturated pixels to detect and correct saturation in other pixels, thereby maintaining measurement precision while preserving focus detection capability.
Solution Approach 2:
The patent changes the saturation parameter characteristics of pixels by assigning different saturation levels to different pixel groups. This allows the system to operate in a regime where at least some pixels remain non-saturated, enabling accurate focus detection even when other pixels are saturated.
2Device complexity
If pixels are used for both image generation and focus detection, then device complexity is reduced, but measurement precision deteriorates due to saturation effects
Solution Approach 1:
The patent makes pixels serve multiple functions: they simultaneously contribute to image generation and focus detection. By implementing different saturation characteristics in different pixel groups, the system maintains measurement precision for focus detection while using the same pixels for image capture, avoiding the need for separate pixel sets.
Solution Approach 2:
Different saturation parameters are assigned to different pixel groups, allowing the system to optimize for both image quality and focus detection accuracy. This parameter differentiation enables the same physical pixels to reliably perform dual functions without mutual interference.
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
The solution enhances focus detection accuracy by correcting charge leakage due to saturation, maintaining image linearity even when pixels are saturated, and enabling precise focus detection in various lighting conditions.
Implementation Method 1
an image pickup element including a plurality of first pixels sharing a first microlens and a plurality of second pixels sharing a second microlens
Data Source
AI summary
A signal processing apparatus which processes signals obtained from an image pickup element including a plurality of first pixels sharing a first microlens and a plurality of second pixels sharing a second microlens, the first pixels and the second pixels having saturation characteristics different from each other, and the signal processing apparatus includes a saturation detector configured to detect a saturated pixel whose charge amount has reached a saturation level among the first pixels and the second pixels, and an estimating portion configured to estimate the charge amount of the saturated pixel using a nearby pixel of the saturated pixel.