A comparison of discrete cosine transform and discrete wavelet transform algorithm in watermarking against common attacks
Digital watermarking is a technique to embed additional data to digital images, audios and videos without affecting the quality of the original image. Watermark can be extracted for ownership verification or authentication. Currently, there is no comparison documented done between Discrete Cosine Tr...
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| Format: | Thesis |
| Published: |
2015
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| Subjects: | |
| Online Access: | http://eprints.uthm.edu.my/6936/ http://eprints.uthm.edu.my/6936/1/MOHAMED_ABDISALAN_SAID.pdf |
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| Summary: | Digital watermarking is a technique to embed additional data to digital images, audios
and videos without affecting the quality of the original image. Watermark can be
extracted for ownership verification or authentication. Currently, there is no comparison
documented done between Discrete Cosine Transform (DCT) and Discrete Wavelet
Transform (DWT). In this report, the DCT watermarking algorithms and DWT
watermarking algorithms were compared based on robustness and imperceptibility
criteria. With DCT, the watermark bits were embedded into the mid-band coefficients of
the DCT in the cover image where the DWT algorithm was embedded the watermark
bits into the horizontal and vertical sub-bands of DWT in the cover image. Experimental
results had shown that the watermark is robust to geometric attacks and removal attacks.
DCT and DWT are compared with regard to peak signal to noise ratio (PSNR), Mean
Square Error (MSE) and Normalized Correlation (NC). The PSNR value of the
watermarked Lena image in DWT is 47, higher than the DCT which is 44. The
Normalized Correlation (NC) also had clarified that the extracted watermark in DWT
0.9964 is greater than the extracted watermark in DCT 0.2057. Thus, the results had
indicated that the DWT gives better image quality than DCT. |
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