A Comparison of DCT and DWT Block Based Watermarking on Medical Image Quality

Dowling, Jason; Planitz, Birgit; Maeder, Anthony; Du, Jia Tina; Pham, Binh; Boyd, Colin; Chen, Shaokang; Bradley, Andrew P.; Crozier, Stuart

doi:10.1007/978-3-540-92238-4_35

Cited by 9 publications

(6 citation statements)

References 5 publications

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“…The DWT approach is an effective process and is probably superior when watermarking is applied to the entire image [ 29 , 30 ]. Determining a favorable watermarking zone for bit embedding is a complex process, and it must proceed through various calculative operations for setting up.…”

Section: Related Workmentioning

confidence: 99%

Encryption Based Image Watermarking Algorithm in 2DWT-DCT Domains

Hasan

Islam

Chen

et al. 2021

Sensors

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This paper proposes an encryption-based image watermarking scheme using a combination of second-level discrete wavelet transform (2DWT) and discrete cosine transform (DCT) with an auto extraction feature. The 2DWT has been selected based on the analysis of the trade-off between imperceptibility of the watermark and embedding capacity at various levels of decomposition. DCT operation is applied to the selected area to gather the image coefficients into a single vector using a zig-zig operation. We have utilized the same random bit sequence as the watermark and seed for the embedding zone coefficient. The quality of the reconstructed image was measured according to bit correction rate, peak signal-to-noise ratio (PSNR), and similarity index. Experimental results demonstrated that the proposed scheme is highly robust under different types of image-processing attacks. Several image attacks, e.g., JPEG compression, filtering, noise addition, cropping, sharpening, and bit-plane removal, were examined on watermarked images, and the results of our proposed method outstripped existing methods, especially in terms of the bit correction ratio (100%), which is a measure of bit restoration. The results were also highly satisfactory in terms of the quality of the reconstructed image, which demonstrated high imperceptibility in terms of peak signal-to-noise ratio (PSNR ≥ 40 dB) and structural similarity (SSIM ≥ 0.9) under different image attacks.

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Section: Related Workmentioning

confidence: 99%

Encryption Based Image Watermarking Algorithm in 2DWT-DCT Domains

Hasan

Islam

Chen

et al. 2021

Sensors

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“…It was indicated by Dowling et al [44] in their comparison between the DWT and DCT block-based watermarking that the DCT approach is more effective at smaller block sizes while the DWT approach is probably superior if the watermarking is applied to the entire image. In [45], Al-Haj proposed using a combination of DWT and DCT to implement blind image watermarking.…”

Section: Selecting the Small Block Size For Embedding Water Mark Informationmentioning

confidence: 99%

Blind and Robust Watermarking Scheme in Hybrid Domain for Copyright Protection of Medical Images

Alzahrani

Memon

2021

IEEE Access

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This work presents a robust watermarking technique in hybrid domain for the copyright claim of medical images. The scheme is a fusion of three popular transforms: Discrete Wavelet Transform (DWT), Discrete Cosine Transform (DCT) and Singular Value Decomposition (SVD). The input image is first separated into region of interest (ROI) and region of non-interest (RONI). The DWT is applied on RONI to get low and high frequency bands. The low frequency band is then segmented into 4  4 blocks. The Human Visual System (HVS) is applied to select the potential blocks for implanting watermark content. Each 4  4 selected block is further subdivided into four 2  2 carrier matrices. The SVD is applied to each carrier matrix. Finally, the hidden information is implanted by altering the largest diagonal singular values of four 2  2 matrices. The technique is blind, so host image is not needed for the extraction of hidden information. The proposed scheme achieves higher values of imperceptibility as well as robustness. Experimental results reveal that the proposed technique outperforms the techniques currently reported in the literature by achieving higher values of imperceptibility in the form of PSNR with value of 44.0567 decibels (dB) and SSIM value of 0.9800. At the same time it achieves excellent values of robustness with maximum NCC value of 1.000 and minimum BER with value of 0.000.

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“…The results also showed that the feature extraction by DCT with ANN yields a higher recognition rate. One reason is that most of the energy of the image is located in the upper -left corner of the 2D array, thus the DCT is more efficient, if the localisation of changes is significant [8,15]. Using only LL3 sub-band of DWT may affect the performance.…”

Section: Comparative Analysis Of Anns and Hmm With Dct And Dwtmentioning

confidence: 99%

An Evaluation of Methods for Arabic Character Recognition

Lawgali¹

2014

IJSIP

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Off-line recognition of text plays a significant role in several applications such as the automatic sorting of postal mail or editing old documents. The recognition of Arabic handwriting characters is a difficult task owing to the similar appearance of some different characters. Most researchers have presented methods that recognise isolated characters. However, recognition of all shapes of Arabic handwritten characters still remains a great challenge. The selection of the methods for feature extraction and classification remain the most important step in achieving high recognition accuracy. The purpose of this paper is to compare the effectiveness of DCT and DWT in capturing discriminative features of all shapes of Arabic handwritten characters including overlapping characters with ANN and HMM in the classification stage. Since, the recognition of handwritten characters is an important step in the recognition of a word after segmentation, this paper ascertains the effectiveness of these techniques in capturing useful information and, hence, achieving more accurate recognition results. This work has been tested with HACDB database containing 6,600 shapes of Arabic characters. The results have demonstrated that the feature extraction by DCT with ANN yields a higher recognition rate.

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A Comparison of DCT and DWT Block Based Watermarking on Medical Image Quality

Cited by 9 publications

References 5 publications

Encryption Based Image Watermarking Algorithm in 2DWT-DCT Domains

Encryption Based Image Watermarking Algorithm in 2DWT-DCT Domains

Blind and Robust Watermarking Scheme in Hybrid Domain for Copyright Protection of Medical Images

An Evaluation of Methods for Arabic Character Recognition

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