Flash Artifact Removal via Non-Flash Edge Detection
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Solution Overview
Problem
Existing methods for removing flash artifacts from images, such as red, silver, or golden eyes, often result in unnatural-looking images or fail to accurately detect the pupil region, especially in low ambient light conditions, leading to 'holes in the eyes' effects and inaccurate corrections.
Innovation Solution
A computer-implemented flash artifact removal apparatus that uses a combination of flash and non-flash images to correct flash artifacts by detecting edges in the non-flash image and replacing affected pixels in the flash image, employing techniques like edge detection, normalization, and weighted blending to produce a more natural-looking output.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If flash photography is used in low ambient light conditions, then image capture is enabled, but red/gold/silver eye artifacts occur
Solution Approach 1:
The system captures a non-flash image before or alongside the flash image to obtain clean eye region data before flash artifacts contaminate the flash image. This preliminary capture of undistorted eye information allows for accurate artifact removal while preserving natural eye appearance.
Solution Approach 2:
The non-flash image serves as an intermediary source of clean eye region information. By using the non-flash image as a reference to identify and replace artifact-contaminated pixels in the flash image, the system mediates between the need for flash illumination and the desire to avoid flash artifacts.
2Object-generated harmful factors
If existing approaches darken the red/gold/silver eye regions, then flash artifacts are removed, but the image appears unnatural with 'holes in the eyes'
Solution Approach 1:
The system applies different processing strategies to different regions: the non-flash image is used specifically for the eye region to preserve natural appearance, while other regions retain their original flash image characteristics. This localized approach ensures natural eye appearance without compromising overall image quality.
Solution Approach 2:
The system copies pixel data from the non-flash image (which contains natural eye appearance) to replace artifact-contaminated pixels in the flash image. This copying process transfers the clean, natural eye region information to the final output, eliminating artifacts while preserving realism.
3Device complexity
If the flash is positioned closer to the optical axis, then camera design is simplified, but flash artifacts worsen
Solution Approach 1:
The system converts the harmful flash artifact problem into a beneficial solution by using image processing techniques. Instead of redesigning the camera hardware to position the flash farther from the optical axis, the system processes the captured images to remove artifacts, thereby maintaining simple camera design while eliminating the harmful visual effects.
Data Source
AI summary
A computer-implemented flash artifact removal apparatus is described. The apparatus has at least a memory storing a flash image depicting a person's face captured in the presence of a flash illumination, and a non-flash image depicting the person's face captured without flash illumination. A plurality of pixels in the flash image comprise artifacts as a result of flash light reflecting from one or more eyes of the person. The apparatus has a flash artifact removal component which corrects the flash image by replacing at least some of the plurality of pixels in the flash image with pixels computed from at least the non-flash image. The flash artifact removal component is configured to detect edges of features of the one or more eyes in the non-flash image and to detect the plurality of pixels to be replaced in the flash image on the basis of the detected edges.