Portrait Skin Tone Brightness Normalization for ID Document Printing
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Solution Overview
Problem
Existing printing technologies face challenges in accurately reproducing portrait images with extremely dark or bright skin tones on identification documents due to their limited dynamic range, leading to saturation or misalignment of color scales.
Innovation Solution
A method for normalizing skin tone brightness in portrait images by determining brightness difference values and adjusting the image brightness using predefined thresholds, ensuring accurate representation on identification documents.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If portrait images with extremely dark or bright skin tones are printed directly on identification documents, then the original skin tone information is preserved, but the print quality deteriorates due to saturation or misalignment of color scales
Solution Approach 1:
The patent applies preliminary brightness normalization to the portrait image before printing. The system calculates a brightness value for the face region, compares it to a predefined threshold, and adjusts the brightness accordingly. This preliminary adjustment ensures that the image brightness falls within the optimal range for printing, preventing saturation and color scale misalignment while preserving accurate skin tone representation on the identification document
Solution Approach 2:
The patent changes the brightness parameter of the portrait image to resolve the contradiction. By adjusting the brightness value based on comparison with a predefined threshold, the system transforms the image into a state suitable for printing. This parameter modification ensures that extremely dark or bright skin tones are normalized to an optimal range, maintaining both skin tone accuracy and print quality
2Manufacturing precision
If the brightness of portrait images is adjusted to normalize skin tone, then print quality improves, but the original image characteristics may be altered
Solution Approach 1:
The patent implements a feedback mechanism where the system calculates the brightness value of the face region, compares it to a predefined threshold, and uses this comparison to determine the appropriate brightness adjustment. This feedback loop ensures that brightness normalization is applied only when necessary and to the extent needed, improving print quality while minimizing alterations to the original image characteristics
Solution Approach 2:
The patent applies partial action by adjusting only the brightness parameter and leaving other image characteristics unchanged. The brightness adjustment is applied selectively based on the comparison result, ensuring that only the necessary modification is made to achieve optimal print quality without unnecessarily altering other aspects of the original image
Data Source
AI summary
Methods, systems, and apparatus, including computer programs encoded on a computer storage medium, for normalizing skin tone brightness are disclosed. In one aspect, a method includes the actions of receiving a color image that includes a representation of a face. The actions further include selecting a group of pixels in the color image that includes the representation of the face. The actions further include determining a brightness value that represents a brightness of the group of pixels in the color image that includes the representation of the face. The actions further include determining a brightness difference value. The actions further include comparing the brightness difference value to an upper threshold brightness difference value and a lower threshold brightness difference value. The actions further include determining whether to adjust a brightness of the color image that includes the representation of the face.