Facial Image White Balance Checking Against Skin-Tone Tables
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Solution Overview
Problem
Facial images captured for security documents often have inaccurate or unrealistic color reproduction due to distorted white balance caused by ambient light, failing to meet stringent requirements for authentication and security document usage.
Innovation Solution
A method to check and adjust the preset white balance of facial images by determining skin-face region color values, comparing them to a skin tone table, and applying manual or systematic corrections based on predetermined thresholds to ensure accurate color representation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a predefined algorithm with preset white balance is used for image processing, then the processing speed and automation are improved, but the color reproduction accuracy deteriorates due to ambient light distortion
Solution Approach 1:
The patent applies preliminary action by pre-defining acceptable color difference thresholds for skin tones before the actual image processing occurs. The system pre-processes the image to identify skin-face regions and pre-calculates color differences against reference skin tone values, enabling automated decision-making about whether white balance adjustment is needed without requiring manual intervention for each image.
Solution Approach 2:
The patent replaces the mechanical/manual white balance adjustment process with an automated computational system. Instead of relying on predefined algorithms that assume ideal lighting conditions, the system uses computer vision to detect skin regions, calculate actual color differences, and automatically determine whether adjustment is needed, substituting manual photographer judgment with automated image analysis.
2Manufacturing precision
If manual white balance adjustment is performed to improve color accuracy, then the color reproduction is improved, but the processing time and operational complexity increase
Solution Approach 1:
The patent applies feedback by using the calculated color difference values to automatically determine the appropriate action. The system calculates the color difference between detected skin regions and reference values, compares this against predefined thresholds, and automatically selects whether white balance adjustment is needed. This closed-loop feedback mechanism eliminates manual judgment while maintaining color accuracy.
Solution Approach 2:
The patent changes the parameter being monitored from general image quality metrics to specific skin-tone color difference values. By focusing on the specific parameter of color difference in skin-face regions and comparing it against reference skin tone values, the system can make precise automated decisions about white balance adjustment needs without requiring manual intervention.
3Reliability
If strict color reproduction requirements are enforced for security documents, then the authentication reliability is improved, but the ease of independent image capture deteriorates
Solution Approach 1:
The patent applies self-service by enabling the image capture device to automatically perform white balance verification and adjustment without requiring a trained photographer. The system allows ordinary users to independently capture facial images for security documents by automatically checking skin tone color differences and adjusting white balance as needed, making the process self-sufficient.
Solution Approach 2:
The patent replaces the mechanical system of trained photographer judgment and manual adjustment with an automated computational system. The image processing system automatically detects skin regions, calculates color differences against reference values, and determines whether white balance adjustment is needed, substituting human expertise with automated image analysis to maintain authentication reliability while enabling independent capture.
Data Source
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AI summary
A computer-implemented method for verifying a preset white balance of at least one facial image, the method comprising: determining a skin-facial region color value for a skin-facial region of the at least one facial image with preset white balance; determining color difference values of the skin-facial region color value to skin tone values in a skin tone table;and checking the preset white balance of the at least one facial image based on a minimum color difference value, wherein the checking comprises: outputting an indication to perform a white balance manually if the minimum color difference value exceeds a first predetermined color difference threshold, or adjusting the white balance based on a systematic color error value if the minimum color difference value falls below the first predetermined color difference value, or outputting an image data set based on the at least one image if the minimum color difference value falls below or equals a second predetermined color difference threshold;