Camera Face Detection Indicator Persistence Control
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Solution Overview
Problem
Digital still cameras face challenges in maintaining accurate automatic exposure and focus control when a subject, particularly a face, is temporarily lost from the center or not detected, leading to inconsistent display times of detected-face indicators and user inconvenience.
Innovation Solution
The camera displays a detected-face indicator based on the last detected face coordinates, even when the face is undetected, allowing for continuous reference for shooting control and reducing the duration of indicator display variability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the detected-face indicator is displayed only when face is detected, then the indicator accurately represents current face location, but the indicator disappears during temporary face loss, causing user inconvenience and inconsistent display time
Solution Approach 1:
The system performs preliminary action by storing the last detected face coordinates before face detection fails. When face is temporarily lost, the system retrieves and displays the previously stored face indicator position, ensuring continuous shooting control guidance without requiring re-detection. This preliminary storage of face coordinate data resolves the contradiction by maintaining indicator display during temporary detection failures.
Solution Approach 2:
The patent introduces an intermediary mechanism - a storage unit that holds last detected face coordinates - which acts as a mediator between face detection failure and shooting control. This intermediary storage buffer allows the system to maintain the detected-face indicator display during temporary face loss, bridging the gap between detection failure and control continuity, thus resolving the contradiction between accurate indication and user convenience.
2Stability of the object's composition
If the detected-face indicator display time is extended during face undetected state, then shooting control stability is improved, but the indicator may display outdated face location information
Solution Approach 1:
The system applies dynamics by making the indicator display behavior adaptive rather than static. The detected-face indicator is displayed continuously during temporary face loss but is automatically updated when face is re-detected. This dynamic adjustment of display persistence based on detection state resolves the contradiction by maintaining stability during transitions while ensuring accuracy upon re-detection.
Solution Approach 2:
The patent changes the parameter of indicator display duration based on detection state. During face undetected state, the display time is extended using stored coordinates; upon face re-detection, the indicator position is updated to new coordinates. This parameter change in display persistence resolves the contradiction between maintaining stable control and preserving location accuracy.
3Adaptability or versatility
If the mode of photometry is changed upon face loss, then exposure control adapts to new subject, but the user cannot take image of original subject in simple and convenient manner
Solution Approach 1:
The system implements feedback by continuously monitoring face detection state and adjusting photometry mode accordingly. When face is detected, face-based photometry is applied; when face is temporarily lost, the system maintains face-based photometry using stored coordinates rather than switching to center-weighted or averaging modes. This feedback-based mode selection resolves the contradiction by maintaining adaptability to the original subject while preserving shooting simplicity.
Data Source
AI summary
An image taking apparatus includes an image taking system, and a display system, and has a CPU implementing a process to detect subject faces from image frames produced by the image taking system, a process to acquire coordinates of detected subject faces, a process to determine a face detected state or a face undetected state, whichever is concluded in accordance with results of face detection, a process to have, for a determination for the face detected state, a detected-face indicator displayed on the display system in accordance with the coordinates of the acquired subject faces, a process to have, for a determination for the face undetected state, a detected-face indicator having been displayed in a last face detected state till the last displayed on, and a process to execute a shooting control in accordance with a detected-face indicator displayed on the display system.