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Simultaneous storage of medical images in the spatial and frequency domain: a comparative study.

Nayak J, Bhat PS, Acharya U R, Uc N - Biomed Eng Online (2004)

Bottom Line: It can be seen from results, the process does not affect the picture quality.Spatial and DFT domain interleaving gave very less %NRMSE as compared to DCT and DWT domain.Among the frequency domain interleaving methods, DFT was found to be very efficient.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of E & C Engg, Manipal Institute Of Technology, Manipal, India 576104. jag.nayak@mit.manapal.edu

ABSTRACT

Background: Digital watermarking is a technique of hiding specific identification data for copyright authentication. This technique is adapted here for interleaving patient information with medical images, to reduce storage and transmission overheads.

Methods: The patient information is encrypted before interleaving with images to ensure greater security. The bio-signals are compressed and subsequently interleaved with the image. This interleaving is carried out in the spatial domain and Frequency domain. The performance of interleaving in the spatial, Discrete Fourier Transform (DFT), Discrete Cosine Transform (DCT) and Discrete Wavelet Transform (DWT) coefficients is studied. Differential pulse code modulation (DPCM) is employed for data compression as well as encryption and results are tabulated for a specific example.

Results: It can be seen from results, the process does not affect the picture quality. This is attributed to the fact that the change in LSB of a pixel changes its brightness by 1 part in 256. Spatial and DFT domain interleaving gave very less %NRMSE as compared to DCT and DWT domain.

Conclusion: The Results show that spatial domain the interleaving, the %NRMSE was less than 0.25% for 8-bit encoded pixel intensity. Among the frequency domain interleaving methods, DFT was found to be very efficient.

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Related in: MedlinePlus

Results of DPCM techniques: a) Original signal b) Reconstructed ECG signal C) Error signal
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Figure 3: Results of DPCM techniques: a) Original signal b) Reconstructed ECG signal C) Error signal

Mentions: The ASCII code of the encrypted text is swapped with the least significant bit of the pixels in the image. Each bit in the ASCII code of the text is placed at last bit of the pixels in the image. This procedure is repeated for all the ASCII codes of given text. It can be seen that one ASCII code can be hidden in eight pixels of the given image. Similarly the graphic files of bio-signals are also interleaved in the pixels using above said procedure. The graphic file is encrypted using DPCM. In this study ECG is used as a bio-signal which is encrypted as given in the section 3.2 of this paper. Fig. 3(a),3(b) and 3(c) are the original, reconstructed and error signals of the DPCM.


Simultaneous storage of medical images in the spatial and frequency domain: a comparative study.

Nayak J, Bhat PS, Acharya U R, Uc N - Biomed Eng Online (2004)

Results of DPCM techniques: a) Original signal b) Reconstructed ECG signal C) Error signal
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC425593&req=5

Figure 3: Results of DPCM techniques: a) Original signal b) Reconstructed ECG signal C) Error signal
Mentions: The ASCII code of the encrypted text is swapped with the least significant bit of the pixels in the image. Each bit in the ASCII code of the text is placed at last bit of the pixels in the image. This procedure is repeated for all the ASCII codes of given text. It can be seen that one ASCII code can be hidden in eight pixels of the given image. Similarly the graphic files of bio-signals are also interleaved in the pixels using above said procedure. The graphic file is encrypted using DPCM. In this study ECG is used as a bio-signal which is encrypted as given in the section 3.2 of this paper. Fig. 3(a),3(b) and 3(c) are the original, reconstructed and error signals of the DPCM.

Bottom Line: It can be seen from results, the process does not affect the picture quality.Spatial and DFT domain interleaving gave very less %NRMSE as compared to DCT and DWT domain.Among the frequency domain interleaving methods, DFT was found to be very efficient.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of E & C Engg, Manipal Institute Of Technology, Manipal, India 576104. jag.nayak@mit.manapal.edu

ABSTRACT

Background: Digital watermarking is a technique of hiding specific identification data for copyright authentication. This technique is adapted here for interleaving patient information with medical images, to reduce storage and transmission overheads.

Methods: The patient information is encrypted before interleaving with images to ensure greater security. The bio-signals are compressed and subsequently interleaved with the image. This interleaving is carried out in the spatial domain and Frequency domain. The performance of interleaving in the spatial, Discrete Fourier Transform (DFT), Discrete Cosine Transform (DCT) and Discrete Wavelet Transform (DWT) coefficients is studied. Differential pulse code modulation (DPCM) is employed for data compression as well as encryption and results are tabulated for a specific example.

Results: It can be seen from results, the process does not affect the picture quality. This is attributed to the fact that the change in LSB of a pixel changes its brightness by 1 part in 256. Spatial and DFT domain interleaving gave very less %NRMSE as compared to DCT and DWT domain.

Conclusion: The Results show that spatial domain the interleaving, the %NRMSE was less than 0.25% for 8-bit encoded pixel intensity. Among the frequency domain interleaving methods, DFT was found to be very efficient.

Show MeSH
Related in: MedlinePlus