Face Region Image Correction with Gradual Lightness Adjustment
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Solution Overview
Problem
Existing digital image correction methods fail to accurately and efficiently correct the lightness and color of human faces in images with complex backgrounds, often resulting in unnatural images or requiring manual correction.
Innovation Solution
An image correction method and apparatus that allows for semi-automatic extraction of the face region using hue, saturation, and lightness information, with a gradual correction degree setting from the inside to the outside of the face region, ensuring accurate and natural correction, even in images with complex backgrounds.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If gradation correction processing is applied to the entire image to correct face lightness, then the face lightness becomes appropriate, but white compression occurs in the background
Solution Approach 1:
The patent divides the image into multiple regions (face region, skin region, hair region, other regions) and applies different correction processing to each region. The correction processing unit applies gradation correction only to the face and skin regions while excluding the background, thereby correcting face lightness without causing white compression in the background.
Solution Approach 2:
The patent applies different correction characteristics to different regions of the image. The face region receives full gradation correction, the skin region receives partial correction with lower correction amount, and the background receives no correction. This local differentiation allows precise face lightness correction while preserving background quality.
2Measurement precision
If gradation correction processing is applied to the entire image to make a dark face lighter, then the face lightness improves, but other faces or regions become too light beyond appropriate range
Solution Approach 1:
The patent segments the image to identify the specific dark face region that requires correction. By applying correction only to the identified face region and excluding other regions, the system corrects the dark face without causing over-lightening of other faces or background areas.
Solution Approach 2:
The patent applies correction with locally differentiated characteristics where the face region receives appropriate correction amount while other regions receive different or no correction. This ensures that only the intended region is corrected to the desired lightness level without affecting other areas.
3Productivity
If automatic face detection is used in images with complex backgrounds, then correction efficiency improves, but detection accuracy decreases leading to failure
Solution Approach 1:
The patent performs preliminary manual specification of the face region by the operator before automatic correction processing. This preliminary action ensures accurate region identification even in complex backgrounds, and then automatic correction is applied based on this accurate specification, combining the accuracy of manual input with the efficiency of automatic processing.
Solution Approach 2:
The patent introduces an intermediary step where the operator specifies the face region, which then serves as the basis for automatic correction processing. This intermediary specification step bridges the gap between automatic detection and manual correction, allowing the system to handle complex backgrounds accurately while maintaining efficient automatic processing.
4Device complexity
If only skin region in face is considered for dodging, then face correction is simplified, but combination with hair color leads to unnatural image
Solution Approach 1:
The patent divides the correction target into multiple regions including face region, skin region, and hair region. Each region is processed with appropriate correction characteristics, and the results are combined to produce a natural-looking corrected image that maintains proper color relationships between skin and hair.
Solution Approach 2:
The patent applies different correction characteristics to different regions: the face region receives standard correction, the skin region receives correction with adjusted amount, and the hair region receives appropriate correction to maintain natural color combination. This local differentiation ensures natural appearance while managing processing complexity.
Data Source
AI summary
An image correction method comprising the steps of: specifying a region including the face of one person in an image of people displayed in a screen of image display means in response to an input from an operator; extracting a correction target region including at least the face of the person in the image, based on information on at least one of hue, saturation, lightness, and a position of an outline of the specified region; setting a degree of correction to be carried out on each position in the correction target region in such a manner that the degree of correction becomes lower from the inside of the correction target region to the outside thereof near a boundary of the correction target region; and correcting at least one of hue, saturation and lightness in the correction target region based on the degree of correction.