Defocus Calculation Accuracy in Image Pickup Apparatus
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing image pickup apparatuses face challenges in accurately calculating defocus amounts due to changes in stop value, focal length, or other optical parameters, which affect the conversion of image shift to defocus, leading to inaccuracies in focus detection.
Innovation Solution
An image pickup apparatus with imaging and focus detection pixels that includes a readout unit, storage unit, addition unit, and conversion coefficient determination unit to read, store, and convert image signals into defocus amounts, with the ability to adjust the addition of frames based on changes in optical information.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If image data from multiple past readouts is added to perform focus detection calculation, then focus detection capability for low-luminance objects is improved, but calculation accuracy of defocus amount deteriorates when stop value or focal length changes during image data acquisition
Solution Approach 1:
The patent applies preliminary action by determining the conversion coefficient for the addition frame based on optical information from a specific frame before the addition operation. This ensures that the conversion coefficient is established in advance based on known optical parameters, preventing accuracy deterioration when optical parameters change during the image data acquisition period.
Solution Approach 2:
The patent implements dynamics by making the conversion coefficient adaptive to changing optical conditions. Instead of using a fixed conversion coefficient, the system dynamically selects or determines the appropriate conversion coefficient based on the optical information (stop value, focal length) of the frames being added, allowing the system to adapt to varying optical parameters while maintaining calculation accuracy.
2Device complexity
If a fixed conversion coefficient is used for converting image shift amount to defocus amount, then calculation process is simplified, but calculation accuracy deteriorates when optical parameters change during image acquisition
Solution Approach 1:
The system performs preliminary determination of the conversion coefficient based on optical information from the addition frame or reference frame before the actual defocus calculation. This preliminary action ensures that the correct conversion coefficient is selected in advance, maintaining accuracy without requiring complex real-time adjustments during the calculation process.
Solution Approach 2:
The patent applies parameter changes by making the conversion coefficient variable based on optical parameters (stop value, focal length). Instead of using a single fixed conversion coefficient, the system adjusts the conversion coefficient according to the specific optical conditions of each frame, thereby maintaining calculation accuracy across different optical parameter settings.
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
Improves the accuracy of defocus amount calculation by determining conversion coefficients based on time-series continuous optical information, enhancing focus detection precision and reducing errors caused by changes in optical parameters.
Implementation Method 1
an image pickup element that includes imaging pixels and focus detection pixels, and performs photoelectric conversion of an object image
Data Source
AI summary
An image pickup apparatus includes an image pickup element that includes imaging pixels and focus detection pixels and that performs a photoelectric conversion of an object image, a readout unit that reads a pair of image signals from the focus detection pixels with a predetermined period, a storage unit that stores the pair of image signals read by the readout unit and optical information of the pair of image signals, an addition unit that adds a plurality of signals of time-series continuous frames of the pair of image signals, and a conversion coefficient determination unit that determines a conversion coefficient that converts an image shift amount of a pair of image signals of an addition frame obtained by the addition unit into a defocus amount, and the conversion coefficient determination unit determines the conversion coefficient of the addition frame based on the time-series continuous optical information.