Autofocus Pixel Selection for Contrast Measurement Accuracy
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Solution Overview
Problem
Existing contrast-based autofocus methods for image capture devices are limited in accuracy and efficiency, as they rely on fixed pixel values and do not adapt well to varying lighting conditions or image zones with different characteristics.
Innovation Solution
A method that dynamically selects a subset of pixel values based on intensity and reliability to generate contrast data, using band-pass filtering and normalization techniques to determine an optimal focus setting for image capture devices, which involves obtaining and processing focus metrics from multiple images with different settings and performing a weighted sum for image zones.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If all pixel values are used to generate contrast data, then the contrast measurement is comprehensive, but the processing time and computational complexity increase
Solution Approach 1:
The patent extracts only the most relevant pixel values for contrast measurement by dynamically selecting a subset of pixels based on their contribution to contrast information. This extraction principle reduces the data volume processed while maintaining measurement accuracy, directly resolving the contradiction between comprehensive measurement and processing time.
Solution Approach 2:
The patent applies partial action by processing only a carefully selected subset of pixels rather than all pixels in the image. The dynamic selection mechanism identifies and processes only those pixels that provide meaningful contrast information, achieving sufficient measurement precision with reduced computational effort and time.
2Productivity
If fixed pixel values are used for contrast-based autofocus, then the processing is simple and fast, but the accuracy and adaptability to varying lighting conditions deteriorate
Solution Approach 1:
The patent introduces dynamics into the pixel selection process by dynamically selecting pixels based on their intensity values and reliability metrics. This dynamic adaptation allows the system to adjust to varying lighting conditions and image characteristics, maintaining high measurement precision without sacrificing processing efficiency through intelligent pixel subset selection.
Solution Approach 2:
The patent changes the parameters used for pixel selection from fixed values to dynamic parameters that adapt to lighting conditions and image characteristics. By using intensity-based and reliability-based selection criteria, the system maintains accuracy across different conditions while keeping processing efficient through selective pixel sampling.
3Measurement precision
If a larger subset of pixel values is selected for contrast data generation, then the contrast measurement is more accurate, but the computational complexity and processing load increase
Solution Approach 1:
The patent extracts only the essential pixel values needed for accurate focus measurement by applying dynamic selection criteria. This extraction approach identifies and processes only the most informative pixels, achieving high measurement precision while minimizing computational complexity through selective data processing.
Solution Approach 2:
The patent applies partial action by processing a carefully curated subset of pixels rather than all available pixel data. The dynamic selection mechanism ensures that the processed subset provides sufficient contrast information for accurate focus determination, achieving high precision with reduced computational burden.
4Reliability
If pixel values from all image zones are processed equally, then the focus determination is comprehensive, but the adaptability to different image zone characteristics is reduced
Solution Approach 1:
The patent applies local quality by treating different image zones differently based on their characteristics. The dynamic pixel selection process adapts to local conditions in different zones, selecting pixels based on their intensity and reliability metrics specific to each zone's lighting and content characteristics, thereby maintaining high reliability and adaptability simultaneously.
Solution Approach 2:
The patent introduces dynamics into the pixel selection process, allowing the system to adapt to varying lighting conditions and image zone characteristics. By dynamically selecting pixels based on local intensity and reliability metrics, the system maintains reliable focus determination across diverse conditions while adapting to local image characteristics.
Data Source
AI summary
A method of determining a focus setting for an image capture device. The method comprises, for each of a plurality of image zones: obtaining a first value of a focus metric for the respective image zone using a first image captured with a first focus setting for the image capture device; obtaining a second value of the focus metric for the respective image zone using a second image captured with a second focus setting for the image capture device; and processing the first value and the second value to obtain an estimated focus setting for the respective image zone. The focus setting is determined by performing a weighted sum of the estimated focus setting for at least two of the plurality of image zones.