Camera Preview Image Selection for Face Detection
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Solution Overview
Problem
Conventional photography apparatuses face difficulties in accurately detecting human faces and setting optimal photographing conditions, such as focus and exposure, when the initial image acquisition is not suitable, leading to unsuccessful face detection and focus adjustment.
Innovation Solution
The method involves acquiring multiple preview images under different photographing conditions, applying a face detection process using weak learn classifiers, and setting the conditions for the image where a face is detected, ensuring optimal focus and exposure for accurate face detection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a single preview image is acquired under fixed photographing conditions, then the photographing process is simple and fast, but face detection may fail when the conditions are not optimal
Solution Approach 1:
The patent applies preliminary action by acquiring multiple preview images under different photographing conditions (different focal positions and exposure conditions) before performing face detection. This ensures that at least one preview image has optimal conditions for face detection, thereby improving the face detection rate without requiring complex post-processing adjustments.
Solution Approach 2:
The patent changes photographing parameters (focal position and exposure conditions) across multiple preview images. By varying these parameters, the system ensures that at least one preview image captures the face with sufficient luminance information and characteristic structures, enabling successful face detection even when initial conditions are not optimal.
2Measurement precision
If multiple preview images are acquired under different photographing conditions, then face detection accuracy improves, but the photographing time increases
Solution Approach 1:
The patent performs the action of acquiring multiple preview images with different photographing conditions in advance, before the actual photographing. This preliminary action ensures that optimal photographing conditions are identified early, allowing the system to proceed directly to face detection without requiring time-consuming adjustments or re-shooting.
Solution Approach 2:
The patent efficiently varies photographing parameters (focal position and exposure) across multiple preview images to quickly identify optimal conditions for face detection. By systematically changing these parameters, the system achieves accurate face detection while minimizing the time required for condition adjustment.
3Reliability
If photographing conditions are not optimal, then the photographing process is simple, but the face cannot be detected due to insufficient luminance information
Solution Approach 1:
The patent changes photographing parameters (focal position and exposure conditions) across multiple preview images to ensure that at least one image captures the face with sufficient luminance information and characteristic structures. This systematic parameter variation improves face detection reliability by ensuring optimal lighting and focus conditions are achieved.
Solution Approach 2:
The patent performs preliminary photographing with different conditions to identify optimal settings before final face detection. This preliminary action ensures that the face is captured with sufficient luminance information, enabling reliable detection without requiring complex real-time adjustments during the actual photographing process.
Data Source
AI summary
Automatic photographing condition setting is achieved with accuracy. For example, when a shutter button is half-pressed, preliminary photographing is carried out under different photographing conditions to acquire preview images. Then, each of the preview images is subjected to a face detection process. Photographing conditions for photographing a person are automatically adjusted to be suitable for a face area in one of the preview images from which a face has been detected.