JPEG Watermark Integrity Verification via DCT Bit Plane Embedding
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Solution Overview
Problem
JPEG image files are vulnerable to forgery and tampering, and existing integrity verification methods, such as passive, signature-based, and watermark-based schemes, have limitations in accuracy and ability to identify tampered regions.
Innovation Solution
A method and device for embedding a watermark in JPEG images using entropy decoding and a watermark-embedding table to determine target bits in the discrete cosine transform coefficients, allowing for the verification of image integrity by comparing embedded and extracted watermarks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a watermark-based scheme is used to verify image integrity, then the ability to identify tampered regions is improved, but the original image must be changed which may affect image quality
Solution Approach 1:
The patent applies local quality by selectively embedding watermark information in specific bit planes of quantized DCT coefficients rather than uniformly across the entire image. The system identifies and modifies only the least significant bits that are least perceptible to human vision, thereby maintaining overall image quality while enabling tamper detection in specific regions.
Solution Approach 2:
The patent changes parameters by operating in the frequency domain (DCT coefficients) rather than the spatial domain, and by manipulating bit plane representations of these coefficients. This allows the watermark to be embedded in a transformed parameter space where modifications are less perceptible, resolving the contradiction between detection capability and image quality preservation.
2Quantity of substance
If signature-based scheme is used for integrity verification, then the data size is reduced, but the ability to identify tampered regions is lost
Solution Approach 1:
The patent segments the image into multiple bit planes of DCT coefficients, with each bit plane serving as an independent carrier for watermark information. This segmentation allows the system to embed sufficient verification data across multiple segments to identify specific tampered regions while keeping the total watermark data size manageable through efficient encoding.
Solution Approach 2:
The patent transitions from the traditional signature approach (one-dimensional verification) to a multi-dimensional watermarking system that operates across bit plane dimensions and spatial dimensions. This allows the verification data to be distributed throughout the image structure, enabling both compact storage and precise location identification of tampered areas.
3Ease of operation
If passive scheme is used for integrity verification, then no image modification is needed, but the verification error rate increases
Solution Approach 1:
The patent applies preliminary action by embedding the watermark into the image during the compression process or immediately thereafter. This pre-embedding of verification information allows the system to achieve high verification accuracy without requiring subsequent modifications to the image, as the protective watermark is already in place before any potential tampering occurs.
Data Source
AI summary
The present disclosure provides a method of embedding a watermark on a Joint Photographic Experts Group (JPEG) image. The method includes: performing an entropy decoding on the JPEG image to generate quantized discrete cosine transform (DCT) coefficients; determining target bits in a bit plane of the quantized DCT coefficients on the basis of a watermark-embedding table (WET); and embedding a watermark based on metadata of the JPEG image in the target bits. Also, the present disclosure provides a method of verifying integrity of the image by using the embedded watermark.