White Balance Adjustment Using Priority Flash Selection
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Solution Overview
Problem
In imaging using multiple auxiliary light sources, such as flash devices, the auto white balance adjustment often results in an image tint that emphasizes the background rather than the main subject, leading to an inappropriate tint for the subject.
Innovation Solution
A white balance adjusting apparatus comprising a non-emission image obtaining unit, emission image obtaining unit, auxiliary light irradiation area specifying unit, priority auxiliary light source selecting unit, and white balance adjustment value calculating unit, which determines the priority auxiliary light source based on signal value differences and light source color information to adjust the white balance accordingly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If auto white balance adjustment is performed based on mixed light ratio in the portion strongly irradiated with flash light, then the background tint is improved, but the main subject tint deteriorates
Solution Approach 1:
The patent segments the image into multiple regions and identifies multiple flash light irradiation areas corresponding to different auxiliary light sources. By dividing the white balance adjustment task across these segmented regions, the system can selectively apply different adjustment strategies to different areas, ensuring the main subject receives appropriate tint correction while the background can be independently optimized.
Solution Approach 2:
The patent applies local quality by performing white balance adjustment specifically on the main subject region rather than uniformly across the entire image. The system identifies the main subject's flash light irradiation area and applies targeted white balance correction to this specific region, preserving the natural appearance of the main subject while allowing different processing for other areas like the background.
2Adaptability or versatility
If multiple auxiliary light sources are used for imaging, then the lighting coverage and flexibility are improved, but the white balance adjustment complexity increases
Solution Approach 1:
The patent performs preliminary action by capturing pre-emission images before the actual imaging with all auxiliary light sources activated. These pre-emission images are taken with individual auxiliary light sources turned on separately, allowing the system to pre-identify each light source's irradiation area and characteristics. This preliminary data collection simplifies the subsequent white balance adjustment process by providing reference information about each light source's effect on different regions.
Solution Approach 2:
The patent implements feedback by using the pre-emission images to guide the white balance adjustment of the actual emission image. The system compares the pre-emission images (showing individual light source effects) with the actual emission image (showing combined light effects) to determine the appropriate white balance adjustment values. This feedback mechanism allows the system to automatically compensate for the complex interactions between multiple light sources without requiring manual intervention.
Data Source
AI summary
A non-emission image is obtained by a non-emission image obtaining unit in a state in which a plurality of flash devices do not emit light. Pre-emission images are obtained by an emission image obtaining unit in a state in which the plurality of flash devices individually emits light. Flash light irradiation areas are specified by a flash light irradiation area specifying unit based on a signal value difference of a plurality of division areas of the non-emission image and each of the emission images. A priority flash device selecting unit selects a priority flash device as a target of white balance (WB) adjustment. A WB adjusting unit performs WB adjustment based on signal values of irradiation areas of the selected priority flash device.