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URN etd-0904114-000508 Statistics This thesis had been viewed 1274 times. Download 0 times. Author Kuo-Hong Pai Author's Email Address No Public. Department Computer Science and Enginerring Year 2013 Semester 2 Degree Master Type of Document Master's Thesis Language zh-TW.Big5 Chinese Page Count 105 Title A Semi-Fragile Watermarking Scheme for JPEG Images Using Quantization Index Modulation Keyword Tamper Detection Semi-fragile Watermarking JPEG Compression Quantization Index Modulation Quantization Index Modulation JPEG Compression Semi-fragile Watermarking Tamper Detection Abstract Digital images being transferred over the Internet can be intercepted and modified without any noticeable difference. Moreover, in order to transfer images faster on the network, people usually compress images in JPEG formats to reduce the image sizes before transmission. This thesis presents a semi-fragile watermarking scheme that can locate the tampered areas on JPEG compressed images.
The proposed scheme includes two phases, one is watermarked image generation phase and the other is integrity verification phase. In the watermarked image generation phase, the scheme embeds the watermark by modifying the relative value with the Quantization Index Modulation. The difference between the relative value modification and the traditional modification is that the former can increase the robustness to resist the JPEG compression and reduce noise. In the integrity verification phase, the previously embedded watermark and the original watermark are compared, and the differences, which indicate the tampered areas, are obtained. Because the non-tampered image has lower noise density than tampered image, the recall rate and precision rate of the tamper detection can be increased with different noise processing.
The experimental results show that, as compared to other methods, the proposed scheme can retrieve the watermarks with high integrity, process the JPEG compressed images with low misjudgment, and detect the tampered areas with high recall rates and precision rates.
Advisor Committee Shang-Lin Hsieh - advisor
Chiung-San Lee - co-chair
Yo-Ping Huang - co-chair
Files Date of Defense 2014-07-31 Date of Submission 2014-09-04