Endoscope Autofocus Control Using Phase Difference Reliability
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Solution Overview
Problem
Existing endoscope systems face challenges in accurately and efficiently performing autofocus control, particularly when dealing with chronologically-continuous frames, as they struggle to maintain processing speed and accuracy in determining subject distance using phase difference detection methods.
Innovation Solution
The system employs a processor to calculate ranging information from phase difference pixels at different optical positions, estimate subject distance using reference information, and determine the reliability of this information to adjust focal positions, ensuring accurate and high-speed autofocus processing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If phase difference detection method is used for autofocus control in endoscope systems, then subject distance can be determined, but processing speed and accuracy are compromised when dealing with chronologically-continuous frames
Solution Approach 1:
The patent applies preliminary action by pre-calculating and storing correspondence relationships between picture-shift amounts and subject distances in reference information before actual autofocus processing. This allows the system to quickly retrieve pre-computed data during real-time operation, avoiding complex calculations on continuous frames while maintaining accuracy.
Solution Approach 2:
The patent uses copying by creating reference information that replicates the relationship between optical system positions and subject distances. Instead of performing full phase difference detection on every frame, the system copies relevant distance-position correspondence data from reference information to determine autofocus settings, significantly reducing processing load while preserving measurement accuracy.
2Reliability
If multiple picture signals are processed to maintain autofocus accuracy, then subject distance determination becomes more reliable, but processing time increases
Solution Approach 1:
The patent extracts only the essential picture-shift amount information from picture signals for autofocus processing, separating this critical data from other image processing tasks. By extracting and focusing solely on the phase difference information needed for distance determination, the system maintains reliability while minimizing processing time.
Solution Approach 2:
The system performs preliminary processing to extract and store picture-shift amount correspondence data in reference information before actual autofocus operation. This pre-extraction allows rapid retrieval during real-time processing, maintaining reliability through multiple data points while avoiding repeated full-frame processing.
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 approach enhances the accuracy and speed of autofocus control in endoscope systems by reliably determining subject distance and adjusting focal positions, improving image quality and operational efficiency.
Implementation Method 1
an imager that includes a phase difference pixel configured to generate a picture signal for generating ranging information correlated to distance from the subject
Data Source
AI summary
A control device includes: a processor configured to obtain a first picture signal and a second picture signal, calculate first ranging information based on the first picture signal, calculate second ranging information based on the second picture signal, estimate a first subject distance corresponding to the first ranging information, estimate ranging information corresponding to a second focal position, perform arithmetic processing to determine degree of reliability of the first ranging information, and output a result of the arithmetic processing.