Temporal Image Watermarking for Imperceptible Screenshot Tracing
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Solution Overview
Problem
Existing methods for protecting image files from unauthorized copying and distribution, such as taking screenshots, are inadequate, as they often result in lower quality copies and make it difficult to trace the source of unauthorized distribution.
Innovation Solution
A method involving alternating two versions of an image with opposite transformations of a watermark overlay, making it imperceptible during normal viewing but visible in screenshots, combined with image processing techniques to ensure the watermark is embedded effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a watermark is overlaid on an image to protect it from unauthorized copying, then the ability to trace distribution sources is improved, but the watermark becomes visible and degrades image quality
Solution Approach 1:
The patent applies periodic action by alternating between two versions of the image (first and second watermarked images) at a refresh rate above the flicker fusion threshold. This temporal oscillation causes the human visual system to perceive a single clean image while capturing devices record both versions, enabling watermark extraction without degrading perceived image quality.
Solution Approach 2:
The patent transitions the watermarking problem from spatial domain to temporal domain by oscillating between two image versions over time. This adds a time dimension to the solution, allowing the watermark to be embedded in the temporal variations rather than directly in the spatial pixels, thereby avoiding visual degradation.
2Object-affected harmful factors
If a watermark is made visible to deter unauthorized copying, then the deterrence effect is improved, but the watermark becomes perceptible and ruins the viewing experience
Solution Approach 1:
By oscillating between watermarked image versions at high frequency, the patent creates a stroboscopic effect where the human visual system integrates the alternating images into a single perceived clean image. The watermark information is preserved in the temporal variations, providing deterrence through detectability while maintaining visual quality.
Solution Approach 2:
The patent uses the display device's refresh mechanism as an intermediary to separate the watermark function from the image display function. The alternating display of watermarked versions serves as the mediator that enables both watermark detection and clean image perception simultaneously.
3Ease of operation
If screenshots are taken to create copies of images, then the ease of distribution is improved, but the image quality degrades due to compression and resolution loss
Solution Approach 1:
The patent applies preliminary action by embedding the watermark in the original image versions before any copying or screenshotting occurs. This pre-embedding ensures that any subsequent copies, regardless of quality degradation, will contain the watermark information, enabling traceability even in low-quality screenshots.
Data Source
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AI summary
A method for the display of an image in a display area, the method comprising: loading a first image file defining a first image comprising a main image and a watermark image overlaying the main image using a first transformation; loading a second image file defining a second image comprising the main image and the watermark image overlaying the main image using a second transformation; and alternating between displaying the first image and the second image in a location within the display area so that the watermark image is imperceptible to a user viewing the display area.