Image Pickup Device Saturation Prediction for Wide Dynamic Range
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Solution Overview
Problem
Conventional image pickup devices face challenges in capturing images with a wide dynamic range due to issues like pixel saturation, noise accumulation, and variations in sensitivity, leading to degraded image quality and incorrect exposure determinations.
Innovation Solution
An image pickup device with a photoelectric conversion unit and electronic shutter function that uses a combination of destructive and nondestructive read-out methods to predict pixel saturation during standard exposure time, allowing for the combination of pixel data from standard and short exposure times to generate High Dynamic Range (HDR) images with reduced noise and accurate tone representation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If saturation determination signals are generated from standard image signals with noise added, then images with wide dynamic range can be acquired, but the quality of the combined image is degraded due to noise and pixel variations
Solution Approach 1:
The patent applies preliminary action by generating saturation determination signals from non-standard image signals (acquired with shorter exposure time and less noise) before combining images. This allows the system to predict which pixels will be saturated in the standard exposure image without being affected by noise in the standard image itself, thereby maintaining high image quality while achieving wide dynamic range
Solution Approach 2:
The patent uses non-standard image signals as an intermediary to determine saturation. Instead of directly using noisy standard image signals to determine saturation, the system uses the cleaner non-standard signals as a mediator to predict saturation, which then guides the selective combination of standard and nonstandard images to produce high-quality HDR output
2Measurement precision
If threshold value is changed according to variations in characteristics of respective pixels, then erroneous determination is reduced, but significant labor to set the threshold value for each pixel is required
Solution Approach 1:
The patent applies self-service by allowing the system to automatically determine saturation using nonstandard image signals without requiring manual threshold setting for each pixel. The nonstandard signals inherently contain information about pixel characteristics and saturation tendencies, enabling the system to self-adjust and make accurate saturation determinations without external intervention or complex calibration procedures
3Adaptability or versatility
If standard exposed image and nonstandard exposed image are taken at separate timings twice, then images with different exposure values are obtained, but a blurred image is resulted
Solution Approach 1:
The patent applies continuity of useful action by acquiring both standard and nonstandard image signals during a single continuous exposure period rather than at separate timings. This allows the photoelectric conversion elements to maintain continuous exposure to the same scene, ensuring that both image sets capture the identical moment and preventing blur from temporal changes in the scene
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 enables the production of images with a wide dynamic range while minimizing noise and erroneous exposure determinations, resulting in improved image quality and stabilized image output.
Implementation Method 1
a photoelectric conversion unit having a plurality of photoelectric conversion elements arranged in a matrix pattern for converting exposed light into electric charges and accumulating the same
Data Source
AI summary
An image pickup device having a photoelectric conversion unit having a plurality of photoelectric conversion elements arranged in a matrix pattern for converting exposed light into electric charges and accumulating the same and an electronic shutter function for controlling the exposure time for each frame including: a first reader for reading out electric charges exposed during a standard exposure time from respective pixels including the photoelectric conversion elements in the exposed area of the photoelectric conversion unit in a destructive read-out method; a second reader for reading out electric charges exposed during a short exposure time, which is an exposure time shorter than the standard exposure time, from the respective pixels including the photoelectric conversion elements during the same exposure period as the first reader in a nondestructive read-out method; and a saturation predictor for predicting whether or not the amounts of accumulated electric charges in the respective pixels being exposed during the standard exposure time are saturated on the basis of a non-standard exposure pixel data including the electric charges being exposed during the short exposure time, which are read out by the second reader.