White Balance Control Using Chromatic Color Extraction
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Solution Overview
Problem
Conventional image-pickup apparatuses face difficulties in performing effective white-balance control when an image contains a small amount of white-color information, as they rely on white and flesh color signals, which may not be present or sufficient in all cases, leading to challenges in adjusting the white balance.
Innovation Solution
The apparatus includes an identification unit to determine the presence of specific chromatic colors, a chromatic-color selection unit to choose a suitable chromatic color for extraction, and white-balance control units to adjust the white balance based on the identified chromatic color, even when white-color information is limited, by bringing the extracted color close to an achromatic or target color value.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If white-balance control is performed using only white-color information, then the control is simple and straightforward, but it fails when white-color information is insufficient or absent in the image
Solution Approach 1:
The white-balance control device is designed to perform multiple functions: it can control white balance using white-color information when available, and switch to using chromatic color information (such as flesh color) when white-color information is insufficient. This multi-functional approach ensures reliable white-balance control across diverse image conditions.
Solution Approach 2:
The system dynamically selects the appropriate color information source based on the actual image content. It evaluates the availability and quality of white-color information and automatically switches between different control methods (white-color-based or chromatic-color-based), making the white-balance control adaptive to varying image conditions.
2Measurement precision
If conventional white-balance control is used that relies on white and flesh color signals, then the control method is well-established, but it cannot effectively adjust white balance when these color signals are insufficient
Solution Approach 1:
The system changes the parameter used for white-balance control based on image conditions. When white-color information is sufficient, it uses white-color parameters; when insufficient, it switches to using chromatic color parameters (such as flesh color parameters). This parameter switching ensures accurate white-balance measurement across different image types.
3Ease of operation
If the system only uses white-color information for white-balance control, then the control process is simple, but it lacks flexibility to handle images with various lighting conditions and color compositions
Solution Approach 1:
The white-balance control process is segmented into multiple pathways: a primary pathway using white-color information for simple cases, and an alternative pathway using chromatic color information for complex cases. This segmentation maintains simplicity where possible while providing flexibility when needed.
Data Source
AI summary
The present invention allows for selecting a predetermined chromatic color for extraction from among a plurality of chromatic colors based on the result of identification of acquired photographing information. When the value of a white extraction area of the photographing information is smaller than a first threshold value, it is determined whether the value of the area of the selected predetermined chromatic color is greater than or equal to a second threshold value. If the value of the predetermined chromatic-color area is determined to be greater than or equal to the second threshold value, white balance is controlled by bringing the value of the predetermined chromatic-color area near to a predetermined target color value.