Block-Based Digital Image Watermarking for Crop-Resistant Detection
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Solution Overview
Problem
Images are often subject to unauthorized use, and existing methods struggle to effectively embed and detect watermarks that can withstand modifications such as cropping and format conversion while remaining imperceptible to the human eye.
Innovation Solution
A pipeline-based approach for digital watermarking that includes preprocessing stages for images and information, using techniques like feature detection, frequency transformation, and channel encoding to embed a decentralized identifier in blocks of a digital image, ensuring the watermark is robust and imperceptible.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If watermarking methods are designed to be robust against modifications (cropping, format conversion), then the watermark detectability is improved, but the image quality degradation increases
Solution Approach 1:
The patent applies different embedding strategies to different regions of the image by dividing it into blocks and selectively embedding watermark bits in specific blocks based on their suitability (e.g., DCT coefficient magnitudes, block variance). This local adaptation allows robust watermarking in suitable regions while preserving quality in sensitive regions.
Solution Approach 2:
The patent transforms the image to the frequency domain (DCT domain) and embeds watermarks by modifying DCT coefficients. By operating in the frequency domain rather than spatial domain, the watermark can be embedded with controlled strength to achieve robustness while minimizing perceptible quality degradation.
2Reliability
If the watermark is embedded using multiple blocks per bit, then the watermark robustness is improved, but the processing complexity increases
Solution Approach 1:
The patent divides the watermark information into multiple bits, with each bit embedded across multiple image blocks. This segmentation approach distributes the watermark information redundantly across the image, providing robustness against block loss while maintaining a systematic processing framework that manages complexity.
Solution Approach 2:
The patent performs preprocessing steps including image blocking, DCT transformation, and selection of suitable blocks before watermark embedding. By preparing the image structure in advance and pre-selecting suitable blocks based on their properties, the actual watermark embedding process becomes more efficient and less complex.
3Reliability
If the watermark embedding process includes preprocessing stages (feature detection, rotation, frequency transformation), then the watermark robustness is improved, but the processing time increases
Solution Approach 1:
The patent performs feature detection, image orientation determination, and preprocessing steps before watermark embedding to ensure the watermark is aligned with image features and will survive subsequent processing. By completing these preparatory steps in advance, the watermark achieves robustness against rotation and feature-based attacks.
Solution Approach 2:
The patent replaces spatial-domain watermark embedding with frequency-domain embedding using DCT transformation. This substitution allows the watermark to be embedded in a domain that is more resistant to common image processing operations while enabling efficient computation through fast DCT algorithms.
Data Source
AI summary
Provided is a method and apparatus for digital image watermarking. In the method and apparatus, a computer system receives a first image and receive information for embedding in the first image. The computer system preprocesses the first image to produce a preprocessed first image and preprocesses the information by at least channel-encoding the information to produce preprocessed information including a plurality of sets of bits. The computer system embeds the preprocessed information in the preprocessed first image by at least selecting a plurality of blocks of the preprocessed first image and embedding in each block of the plurality of blocks a respective set of bits of the plurality of sets of bits. Each set of bits of the plurality of sets of bits is embedded in a minimum number of blocks of the plurality of blocks, where the minimum number of blocks is greater than one.