Focus Detection Apparatus Abnormal Signal Handling
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Solution Overview
Problem
The increasing number of pixels in image sensors leads to longer phase difference detection processing times, and the inclusion of abnormal signal levels during pixel addition or reduction processing can degrade the accuracy of focus adjustment in phase difference methods.
Innovation Solution
A focus detection apparatus and method that includes a determination unit to identify abnormal signal levels, a calculation unit for filter processing using predetermined coefficients, and a generation unit to generate information on the effect of abnormal signals, allowing for improved focus detection based on filtered signals and saturation information.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If pixel addition or reduction processing is performed to reduce the number of pixels, then processing time is reduced, but the inclusion of abnormal signal levels degrades detection accuracy
Solution Approach 1:
The patent applies preliminary action by performing determination processing before filter processing to identify abnormal signal levels in pixel signals. This preliminary identification allows the system to exclude abnormal signals from subsequent pixel addition/reduction processing, ensuring that accuracy is maintained while still achieving time reduction through filtering. The determination unit checks each pixel signal against reference ranges before the calculation unit performs filter processing, preventing abnormal signals from degrading the final detection accuracy.
Solution Approach 2:
The patent segments the signal processing into distinct stages: first determining whether each pixel signal is normal or abnormal, then separately processing normal signals through filter processing. This segmentation allows the system to handle abnormal signals differently (by excluding them) while still performing efficient filter processing on the remaining normal signals, thus resolving the contradiction between processing speed and accuracy.
2Productivity
If the reference range for pixel addition/reduction processing is widened, then more pixels can be processed, but the number of pixels with abnormal signal levels increases
Solution Approach 1:
By performing determination processing as a preliminary step before filter processing, the system can safely widen the reference range for pixel addition/reduction processing. The preliminary identification of abnormal signals ensures that even when more pixels are included in the processing range, abnormal signals are excluded from the final calculation, thus maintaining accuracy while increasing processing throughput.
3Loss of time
If all pixel signals are used for phase difference detection, then processing time is minimized, but abnormal signal levels reduce accuracy
Solution Approach 1:
The patent extracts abnormal signals from the overall pixel signal set through determination processing. By identifying and separating abnormal signals based on reference range comparisons, the system can then perform filter processing only on normal signals. This extraction approach minimizes the impact of abnormal signals on detection accuracy while still utilizing the majority of pixels for efficient processing.
Solution Approach 2:
The determination processing serves as a preliminary filtering step that quickly identifies abnormal signals before the main phase difference detection processing. This preliminary action allows the system to proceed with efficient filter processing on validated signals without the time penalty of extensive verification during the main detection phase.
Data Source
AI summary
A focus detection apparatus comprises a determination unit that determines whether a first signal output from an image sensor satisfies a predetermined condition, and outputs first information indicating a result of the determination, a calculation unit that performs filter processing on a plurality of the first signals using predetermined coefficients at a predetermined cycle and outputs a second signal, a generation unit that generates second information showing an effect of the first signal which satisfies the predetermined condition on the second signal using the coefficients and plural pieces of the first information corresponding to the plurality of the first signals used in the filter processing, and a focus detection unit that detects a focus state based on a plurality of the second signals and the second information.