Digital Camera Autofocus Sub-region Filtering
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Solution Overview
Problem
Conventional digital photographing apparatuses often fail to accurately focus on subjects not centered in the photograph region due to unnecessary data inaccuracies when focusing on the entire region, leading to poor focusing performance.
Innovation Solution
The method divides the photograph region into sub-regions, calculates focal position values, selects values with differences equal to or less than a threshold from the average focal position, and moves the focal lens to the position with the shortest focal distance, ensuring balanced focusing across the entire region.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the photograph region is divided into sub-regions for focusing, then focusing accuracy on the subject is improved, but the device complexity increases
Solution Approach 1:
The photograph region is divided into multiple sub-regions, and focusing is performed separately on each sub-region. This segmentation allows the system to identify the subject's location more accurately by comparing focal position values across different sub-regions, thereby improving focusing accuracy while managing complexity through a systematic approach.
2Reliability
If the focal lens is moved to the focal position with the shortest focal distance among selected values, then the probability of focusing on the desired subject increases, but the reliability of balanced focusing across the entire region may deteriorate
Solution Approach 1:
The system calculates the average focal position value from all sub-regions and uses it as a reference. Focal position values that deviate significantly from the average are filtered out using a threshold criterion. This feedback mechanism ensures that the selected focal position is both close to the overall average (maintaining balanced focusing) and represents a valid subject focus point (ensuring subject focusing reliability).
Data Source
AI summary
Provided are an automatic focusing method in which a photograph region is brought into focus through automatic movement of a focal lens to a focal position, in response to a photographing-command signal, and a digital photographing apparatus using the method. The method includes dividing the photograph region into a plurality of sub-regions, focusing on the sub-regions and obtaining focal position values DSFOC, calculating an average focal position value ADSFOC of the focal position values DSFOC, selecting focal position values DSFOC whose differences from the average focal position value ADSFOC are equal to or less than a threshold value DTH, and moving the focal lens to a focal position corresponding to the focal position value DSFOC having the shortest focal distance among the selected focal position values DSFOC.