Flash Control for Face Region White Compression Prevention
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Digital cameras often experience white compression issues when adjusting flash amounts, leading to uncorrectable image problems that require rephotography.
Innovation Solution
The implementation of photography apparatuses and methods that include auxiliary light emission and image processing to adjust luminance and/or gradation of detected targets, such as human faces, during photography, either by reducing auxiliary light or lowering imaging gain to prevent white compression.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If the amount of auxiliary light is increased to properly expose dark subjects, then the subject illumination is improved, but white compression occurs on the face making it look overly whitish
Solution Approach 1:
The patent applies local quality by making different parts of the image receive different amounts of auxiliary light. Specifically, the face region is excluded from flash emission while other dark regions receive proper illumination. This is achieved by detecting face regions in the preliminary image and setting the flash emission amount to zero for those regions while maintaining normal flash emission for non-face regions, thereby preventing white compression on faces while still illuminating dark subjects appropriately.
2Illumination intensity
If flash emission is performed to illuminate dark subjects, then subject visibility is improved, but face overexposure occurs causing white compression
Solution Approach 1:
The patent segments the image into face regions and non-face regions based on preliminary image analysis. By detecting facial features such as eyes, nose, and mouth contours, the system divides the subject area into protected face zones and illuminatable non-face zones. This segmentation allows differential flash emission control where faces are protected from overexposure while other dark regions receive necessary illumination.
Solution Approach 2:
The patent performs preliminary action by capturing a preliminary image before actual photography to identify face regions. This preliminary analysis allows the system to pre-determine which areas should be protected from flash emission. The face detection and region segmentation are completed in advance, enabling the main photography to proceed with optimized flash emission settings that prevent face overexposure while ensuring proper illumination of dark subjects.
3Manufacturing precision
If subsequent image processing is used to correct white compression, then image quality can be improved, but the correction is impossible making rephotography necessary
Solution Approach 1:
The patent applies preliminary anti-action by preventing white compression before it occurs in the first place. Through preliminary image analysis and face region detection, the system proactively identifies areas that would be subject to overexposure. It then pre-configures the flash emission to exclude these protected regions, thereby preventing the harmful effect of white compression before the actual photography takes place, eliminating the need for subsequent correction or rephotography.
Data Source
AI summary
In order to prevent white compression from occurring in an image obtained by photography with a photography apparatus such as a digital camera, preliminary photography is carried out and actual photography is carried out while a flash control unit reduces an amount of light from a flash in the case where a predetermined target such as a human face is included in a preliminary image. Image processing is carried out on an actual image obtained through the actual photography for adjusting luminance and/or gradation of the predetermined target in the actual image.