• 한국컴퓨터산업교육학회:학술대회논문집
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• 2003.11a
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• pp.5-10
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• 2003

본 논문에서는 wavelet을 이용한 워터마크 삽입 시스템 구현을 제안한다. wavelet 변환 기법은 JPEG2000 이나 MPEG-4와 같은 차세대 데이터 압축 표준의 기본적 연산으로서 DCT연산에 비해 주파수 해상도와 시간해상도를 모두 만족시킨다. 제안한 시스템은 크게 DWT 변환모듈, 워터마크 삽입모듈, IDWT 복원모듈, Main Controller모듈로 구성된다. DWT 변환모듈은 Haar 웨이블렛 변환알고리즘을 기반으로 설계 됐으며 1차 신축을 통해 변환된 주파수 영역에서 중간주파수 대역(LH 및 HL)을 선택하여 워터마크를 삽입하는 워터마크 삽입 모듈, IDWT를 이용 신호를 복원하는 모듈, 전체시스템 구성 블록을 제어하는 Main Controller모듈로 구성된다.

• Journal of Korea Multimedia Society
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• v.17 no.12
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• pp.1402-1411
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• 2014

Buyer-seller watermarking protocol is defined as the practice of imperceptible altering a digital content to embed a message using watermarking in the encryption domain. This protocol is acknowledged as one kind of copyright protection techniques in electronic commerce. Buyer-seller watermarking protocol is fundamentally based on public-key cryptosystem that is operating using the algebraic property of an integer. However, in general usage, digital contents which are handled in watermarking scheme mostly exist as real numbers in frequency domain through DCT, DFT, DWT, etc. Therefore, in order to use the watermarking scheme in a cryptographic protocol, digital contents that exist as real number must be transformed into integer type through preprocessing beforehand. In this paper, we presented a new watermarking scheme in an encrypted domain in an image that is based on the block-DCT framework and homomorphic encryption method for buyer-seller watermarking protocol. We applied integral-processing in order to modify the decimal layer. And we designed a direction-adaptive watermarking scheme by analyzing distribution property of the frequency coefficients in a block using JND threshold. From the experimental results, the proposed scheme was confirmed to have a good robustness and invisibility.

• Journal of Broadcast Engineering
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• v.13 no.4
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• pp.489-500
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• 2008

We propose a novel high-definition content watermarking algorithm that is highly feasible in UCC (User Created Contents) environment. We begin by addressing an association between broadcasting content and UCC in a view of copyrights, then present watermark requirements by analyzing various UCC editing-effect. Also, we provide a brief review of previous watermarking techniques that are supposed to satisfy the requirements. Our proposed scheme inserts a invisible watermark into both DC and AC components on $8{\times}8$ block DCT domain and extracts them after synchronization using DC image. Experimental results show that our technique satisfies the requirements of invisibility and robustness to a variety of attacks such as rotation, scaling, cropping, and JPEG compression, etc. Note that the proposed scheme is highly resilient to UCC edit attacks that are combined by many different types of watermark attacks.

• Journal of Internet Computing and Services
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• v.8 no.3
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• pp.33-43
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• 2007

In this proper, we proposes a robust watermarking against the lossy compression in the Hadamard domain. The Hadamard matrix consists of only 1 or -1 and can be computed veru fast. The Hadamrd transform has the inverse transform therefore it is able to be applied into the watermarking technology. In embedding process, we select 10 coefficients from intermediate frequency domain and create two watermark patterns. In extraction process, we use the watermark patterns and compare them to detect the watermark information. When we use the standard image ($512{\times}512$) and binary watermark image ($64{\times}64$), the results of these examines are PSNR for $38{\sim}42dB$ and BER for $3.9{\sim}12.5%$. The JPEG QF between 30 and100, naked human eyes can detect to watermark image easily. The experimental results show that performance of Hadamard domain is better than those of DCT, FFT, and DWT.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.8 no.2
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• pp.1-8
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• 2008

The object of watermarking is to prevent from copying and distributing without the copyright or right of ownership. In case of using watermark as an image data we can detect watermark whether an original image exists or not. In this paper, we proposed that an image data is used for watermark and the watermark is detected without an original image. After the original image is transformed with DWT and the watermark is transformed with DCT, they are transformed with binary number. We calculate an optimal bit position for concealing watermark of an original binary image and insert the watermark and determine the best position for robustness against JPEG compression, filtering, and resampling attacks within inserted watermark image. In this paper, we are able to confirm the right of copyright and ownership easily while using invisible watermark and also we can detect a watermark without an original image.

• Journal of the Institute of Convergence Signal Processing
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• v.16 no.4
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• pp.122-128
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• 2015

As multimedia information is spread over cyber networks, problems such as protection of legal rights and original proof of an information owner raise recently. Various image transformations of DCT, DFT and DWT have been used to embed a watermark as a token of ownership. Recently, SVD being used in the field of numerical analysis is additionally applied to the watermarking methods. A watermarking method is proposed in this paper using Gabor cosine and sine transform as well as SVD for embedding and extraction of watermarks for digital images. After delivering attacks such as noise addition, space transformation, filtering and compression on watermarked images, watermark extraction algorithm is performed using the proposed GCST-SVD method. Normalized correlation values are calculated to measure the similarity between embedded watermark and extracted one as the index of watermark performance. Also visual inspection for the extracted watermark images has been done. Watermark images are inserted into the lowest vertical ac frequency band. From the experimental results, the proposed watermarking method using the singular vectors of SVD shows large correlation values of 0.9 or more and visual features of an embedded watermark for various attacks.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2002.05a
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• pp.185-188
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• 2002

With improved network system and development of computer technology, a lot of hospitals are equipping PACS that deals with process and transmission of the medical images. Owing to equipment of PACS the problems on transmission and storage of the medical images were treated. The way to solve the problems is to use various image processing techniques and compression methods This paper describes RLC in lossless image compression method, JPEG using DCT in loss image compression applied to medical images as way implementing DICOM standard. Now the medical images were compressed with Wavelet transform method have been taken advantage of image process. And compression rate of each compression methods was analyzed.

• Proceedings of the IEEK Conference
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• 2005.11a
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• pp.949-952
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• 2005

We propose the hardwired distributed arithmetic which is applied to multiple constant multiplications and the fixed data path in the inner product of fixed coefficient as a result of variable radix-2 multi-bit coding. Variable radix-2 multi-bit coding is to reduce the partial product in constant multiplication and minimize the number of addition and shifts. At results, this procedure reduces the number of partial products that the required multiplication timing is shortened, whereas the area reduced relative to the DA architecture. Also, this architecture shows the best performance for DCT/IDCT and DWT architecture in the point of area reduction up to 20% from reducing the partial products up to 40% maximally.

• Proceedings of the Korea Information Processing Society Conference
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• 2004.11a
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• pp.867-870
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• 2004

본 논문은 비디오 워터마킹에 관한 연구로서 기존의 DCT변환을 한 후 동영상에 워터마크를 삽입하는 방법과는 달리, 압축과정이나 다른 다양한 공격에 대한 강인성에 초점을 두었다. 이 기법은 DWT 기반의 블라인드 비디오 워터마킹으로서 인간 시각적 특성에서 비지각성을 유지하기 위한 방법이다. 칼라영상을 LUV 좌표계로 변환하여 인간 시각에 둔감한 U영역에 서로 다른 장면의 I-프레임에 대해서 웨이블릿 영역 안에 8bit-plane을 한 후, 1단계 웨일블릿 변환을 거친 부호화된 워터마크에 랜덤한 키를 이용하여 삽입한다. 이 기법은 독립적인 워터마크를 HH1를 제외한 나머지 고주파 부대역 영역에 워터마크를 삽입하고 추출 시에는 삽입된 키를 이용하여 추출하였다. 그리고, 제안한 비디오 워터마킹 알고리즘은 효과적으로 풀리지 않았던 프레임 드로핑과 같은 공격들에 대한 강인함을 기존의 방법과 비교 실험하였다. 이는 최초의 영상 없이 삽입된 워터마크 정보를 실시간으로 검색하여 추출할 수 있다.

• Proceedings of the Korean Information Science Society Conference
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• 2005.07a
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• pp.181-183
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• 2005

저작권 보호 기술의 하나인 디지털 워터마킹은 디지털 콘텐츠에 삽입되어 저작권 확인 및 증명에 이용될 뿐만 아니라 영상의 위변조 판별에도 이용된다. 즉, 영상이 변조되는 경우 삽입된 워터마크가 변형됨으로써 위변조 여부 및 위변조 영역의 확인도 가능하다. 본 논문에서는 이와 같이 영상의 위변조 여부를 판별하기 위한 인증 워터마킹 기법으로 적응적인 양자화 워터마킹 기법을 제안한다. 워터마크 삽입 과정은 영상에 DWT를 수행한 뒤 저주파 영역에 블록 DCT를 수행하여 계수들을 변형시키는 방법으로 수행되며, 이를 위해 원신호의 파워를 고려한 적응적인 양자화 방식을 제안하였다. 실험 결과 제안 방식에 의해 워터마크 삽입된 영상은 화질적으로 원영상과 차이가 없고 압축에 대한 강인성도 우수하여 인증 워터마킹에 적합함을 확인하였다.