Camera Auto-Focus Control Apparatus Subject Detection
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Solution Overview
Problem
Existing auto-focus control systems face challenges in accurately determining whether a subject is special or ordinary, leading to inappropriate focus adjustments and resulting in out-of-focus images, especially when dealing with subjects that exhibit sharp luminance changes.
Innovation Solution
A control apparatus and method that compares local peaks of assessment values with local peaks of integrated luminance values to determine if a subject is special or ordinary, selecting an appropriate mode for focus adjustment, such as the long-filter mode for special subjects, to improve focus accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the long-filter mode peak search technique is applied to special subjects with sharp luminance changes, then the probability of erroneous operation is reduced, but the focus position is moved greatly causing the resulting image to become long-time and out-of-focus
Solution Approach 1:
The system dynamically switches between standard mode and long-filter mode based on real-time detection of special subjects. The mode selection unit monitors assessment value variations and integrated luminance value changes to determine when long-filter mode is necessary, applying it only temporarily during special subject conditions rather than continuously
Solution Approach 2:
The system changes the processing parameters by switching between standard peak search mode and long-filter mode. When special subjects are detected through comparison of assessment value peaks with integrated luminance value peaks, the system transitions to long-filter mode with different calculation parameters (longer moving average window), and reverts to standard mode when normal conditions are detected
2Productivity
If the long-filter mode peak search technique is applied to ordinary subjects, then the focus search is performed, but the resulting image becomes long-time and out-of-focus causing the viewer to feel odd
Solution Approach 1:
The system dynamically adapts its behavior based on subject type detection. By continuously monitoring the relationship between assessment value peaks and integrated luminance value peaks, the system identifies when ordinary subjects are present and switches to standard mode, avoiding the application of long-filter mode to ordinary subjects that would produce unnatural images
Solution Approach 2:
The system uses feedback from comparing assessment value peaks with integrated luminance value peaks to determine subject type. This feedback mechanism allows the system to automatically adjust its focus search behavior, applying long-filter mode only when the feedback indicates special subject conditions are present
3Productivity
If standard peak search technique is applied to special subjects with sharp luminance changes, then the focus search is performed, but peak detection error occurs and accurate focusing becomes difficult
Solution Approach 1:
The system changes the measurement parameters by switching from standard peak search to long-filter mode when special subjects are detected. The long-filter mode uses longer moving averages of luminance additive values and assessment values, which smooths out the sharp luminance changes characteristic of special subjects and enables accurate peak detection despite the rapid variations
Solution Approach 2:
The long-filter mode acts as a cushioning mechanism that anticipates and compensates for sharp luminance changes. By using longer moving averages before peak detection occurs, the system pre-smooths the data to reduce the impact of sudden luminance variations, thereby preventing peak detection errors
Data Source
AI summary
A control apparatus for controlling a driver driving an optical element of an image pickup device to adjust a focus position of the image pickup device in the capturing of an image of a subject, includes a local peak comparing unit for comparing a local peak of an assessment value, as a parameter for adjusting the focus position, with a local peak of an integrated luminance value, the assessment value assessing an out-of-focus level of the captured image of the subject on a per field image basis, and the integrated luminance value being obtained by integrating a luminance value of the captured image of the subject on a per field image basis, and a mode selecting unit for selecting, from among a plurality of prepared modes, a mode searching for a peak over the entire range of the assessment value based on the comparison result provided by the local peak comparing unit.