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웨이브렛 변환 계수의 특성을 이용한 생체 영상 암호화 알고리즘
신종홍,Shin, Jonghong 디지털산업정보학회 2016 디지털산업정보학회논문지 Vol.12 No.2
Lossless encryption methods are more applicable than lossy encryption methods when marginal distortion is not tolerable. In this research, the author propose a novel lossless symmetric key encryption/decryption technique. In the proposed algorithm, the image is transformed into the frequency domain using the lifting wavelet transform, then the image sub-bands are encrypted in a such way that guarantees a secure, reliable, and an unbreakable form. The encryption involves scattering the distinguishable frequency data in the image using a reversible weighting factor amongst the rest of the frequencies. The algorithm is designed to shuffle and reverse the sign of each frequency in the transformed image before the image frequencies are transformed back to the pixel domain. The results show a total deviation in pixel values between the original and encrypted image. The decryption algorithm reverses the encryption process and restores the image to its original form. The proposed algorithm is evaluated using standard security and statistical methods; results show that the proposed work is resistant to most known attacks and more secure than other algorithms in the cryptography domain.
웨이브렛 패킷 변환의 특성을 이용한 영상 암호화 알고리즘
신종홍,Shin, Jonghong 디지털산업정보학회 2018 디지털산업정보학회논문지 Vol.14 No.2
Encryption of digital images has been requested various fields. In the meantime, many algorithms based on a text - based encryption algorithm have been proposed. In this paper, we propose a method of encryption in wavelet transform domain to utilize the characteristics of digital image. In particular, wavelet transform is used to reduce the association between the encrypted image and the original image. Wavelet packet transformations can be decomposed into more subband images than wavelet transform, and various position permutation, numerical transformation, and visual transformation are performed on the coefficients of this subband image. As a result, this paper proposes a method that satisfies the characteristics of high encryption strength than the conventional wavelet transform and reversibility. This method also satisfies the lossless symmetric key encryption and decryption algorithm. The performance of the proposed method is confirmed by visual and quantitative. Experimental results show that the visually encrypted image is seen as a completely different signal from the original image. We also confirmed that the proposed method shows lower values of cross correlation than conventional wavelet transform. And PSNR has a sufficiently high value in terms of decoding performance of the proposed method. In this paper, we also proposed that the degree of correlation of the encrypted image can be controlled by adjusting the number of wavelet transform steps according to the characteristics of the image.
웨이브렛 변환 영역에서의 벡터 양자기를 사용한 영상코딩에 관한 연구
池仁鎬,申鍾洪 홍익대학교 산업기술연구소 1999 産業技術 Vol.9 No.-
Image compression is very essential for application such as transmission and storage in data bases. We use wavelet transform in order to propose a new scheme for image compression taking into account psychovisual feature both in the space and frequency domains. We use the vector quantizer using multi-resolution codebook of wavelet coefficients in order to obtain the most efficient compression. The wavelet transform must be at least biorthogonal in order to save CPU time, the corresponding algorithm must be fast. The lowest level subimage is scalar quantized and the other subimages are vector-quantized. We use Linde-Buzo-Gray(LBG) algorithm for codebook of vector quantize. We obtain 31.08 dB(PSNR) image performance in 1 bpp rate with computer simulation. Thus we obtain 0.23 dB performance improvement copmared to early published results. This result can be used as the most efficient compression of image codec in the multi-resolution image process and can be provided as selective service for application of super-high communication network in a progressive transmission scheme. Also this research can be applied to the moving image code.