Frequency Domain Watermark Embedding for Geometric Distortion Robustness
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Solution Overview
Problem
Existing watermarking technologies fail to robustly embed and extract data that is resistant to geometric distortion, low-quality imaging, and unauthorized copying, while maintaining the quality of the original image and hiding the presence of the watermark.
Innovation Solution
A method involving the conversion of an original image into a noise-based image using a two-dimensional magnitude spectrum and random phase in the frequency domain, with specific adjustments to embed and extract watermark data, including block-based pixel modifications and frequency domain processing for robustness and scalability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If watermark data is embedded into an original image using conventional watermarking technology, then watermark data can be extracted through image processing, but the watermark data can be extracted in the case of unauthorized copying and the watermarking technique is not robust against geometric distortion and low-quality photographing
Solution Approach 1:
The patent applies parameter changes by transforming the watermark embedding approach from spatial domain to frequency domain. The original image is converted to frequency domain using Fourier transform, and watermark data is embedded by modifying frequency coefficients rather than pixel values. This transformation makes the watermark more robust against geometric distortions and low-quality photographing while maintaining resistance to unauthorized copying attempts.
Solution Approach 2:
The patent introduces a correction image as an intermediary element in the watermark extraction process. The correction image is generated by comparing the processed image with the original image in the frequency domain, and it serves as a mediator to enhance the extraction of watermark data under various degradation conditions. This intermediary mechanism allows successful watermark recovery even when the watermarked image undergoes geometric distortion or low-quality photographing.
2Loss of information
If watermark data is embedded into an original image, then watermark data can be extracted, but the quality of the original image is impaired due to the embedding of the watermark data
Solution Approach 1:
The patent changes the parameter domain from spatial to frequency domain for watermark embedding. By modifying frequency coefficients rather than pixel intensities, the watermark becomes imperceptible to human vision while remaining extractable through frequency domain processing. This approach minimizes the impact on original image quality while preserving watermark extraction capability.
Solution Approach 2:
The patent replaces the conventional spatial domain watermark embedding mechanism with a frequency domain mechanism. Instead of directly modifying pixel values (mechanical approach), the system uses Fourier transform to convert the image to frequency domain, embeds watermark by adjusting frequency coefficients, and then transforms back. This substitution allows watermark embedding without visible degradation of image quality.
3Loss of information
If watermark data is embedded into an original image, then watermark data can be extracted, but it is revealed whether or not watermark data is embedded
Solution Approach 1:
The patent transforms the watermark embedding from spatial domain to frequency domain, changing the parameter representation of the image. Watermark data is embedded by modifying frequency coefficients which are imperceptible to human vision. The frequency domain representation allows watermark embedding without creating visible artifacts, maintaining the invisibility of the watermark while enabling extraction through frequency domain analysis.
4Quantity of substance
If the size of the original image increases, then more watermark data can be embedded, but the complexity of the embedding and extraction methods increases
Solution Approach 1:
The patent applies a universal frequency domain watermarking method that can handle images of any size. The Fourier transform and frequency coefficient modification approach works consistently regardless of image dimensions. The method embeds watermark data proportionally to the image size, allowing larger images to accommodate more watermark data while using the same fundamental algorithm, thus avoiding increased complexity.
Data Source
AI summary
Provided is a method of embedding and extracting watermark data that is robust against geometric distortion and low-quality photographing and for which the probability of successfully extracting watermark data for an original image is high, while the probability of successfully extracting the watermark data in the case of unauthorized copying is seriously impaired. The data embedding method according to an embodiment of the present invention comprises a step of converting the noise-based image using watermark data, and a step of adjusting the original image using the converted noise-based image.