• Journal of the Korean Institute of Telematics and Electronics S
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• v.36S no.8
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• pp.101-112
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• 1999

In this paper, the codebook design method of VQ (vector quantization) is proposed an method to extract feature data of image for multimedia information searching. Conventional VQ codebook design methods are unsuitable to extract the feature data of images because they have too much computation time, memory for vector decoding and blocking effects like DCT (discrete cosine transform). The proposed design method is consists of the feature extraction by WT (wavelet transform) and the data group divide method by PCA (principal component analysis). WT is introduced to remove the blocking effect of an image with high compressing ratio. Computer simulations show that the proposed method has the better performance in processing speed than the VQ design method using SOM (self-organizing map).

• Journal of the Korea Institute of Information and Communication Engineering
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• v.8 no.2
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• pp.352-358
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• 2004

This paper is studied the improvement of performance for moving picture encoder using H.263. This is used the new motion vector search algorithm using a relation with neighborhood search point and is applied the integer DCT for the encoder. The integer DCT behaves DCT by the addition operation of the integer using WHT and a integer lifting than conventional DCT that needs the multiplication operation of a floating point number. Therefore, the integer Dn can reduce the operation amount than basis DCT with having an equal PSNR. The new motion vector search algorithm is showed almost similar PSNR as reducing the operation amount than the conventional motion vector search algorithm. To experiment a compatibility of the integer DCT and the conventional DCT, according to result compare case that uses a method only and case that uses the alternate two methods of the integer DCT or the conventional DCT to H.263 encoder and decoder, case that uses the alternate two methods is showed doing not deteriorate PSNR-and being each other compatible visually than case that uses an equal method only.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.10
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• pp.61-67
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• 2016

With the current high distribution rate of smart devices and the recent development of computing technology, user interest in multimedia, such as photos, videos, and so on, has rapidly increased, which is a departure from the simple pattern of information retrieval. Because of these increasing interests, image processing techniques, which generate and process images for diverse applications, are being developed. In entertainment recently, there are some techniques that present a celebrity's image as a mosaic comprising many small images. In addition, studies into the mosaic technique are actively conducted. However, conventional mosaic techniques result in a long processing time as the number of database images increases, because they compare the images in the databases sequentially. Therefore, to increase search efficiency, this paper proposes an algorithm to generate a mosaic image using a discrete cosine transform (DCT) hash. The proposed photo mosaic-generation algorithm is composed of database creation and mosaic image generation. In database creation, it first segments images into blocks with a predefined size. And then, it computes and stores a DCT hash set for each segmented block. In mosaic generation, it efficiently searches for the most similar blocks in the database via DCT hash for every block of the input image, and then it generates the final mosaic. With diverse experimental results, the proposed photo mosaic-creation algorithm can effectively generate a mosaic, regardless of the various types of images and sizes.

• Journal of Korea Society of Industrial Information Systems
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• v.14 no.3
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• pp.15-21
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• 2009

In this paper, we proposed an iterative digital image watermarking technique using encrypted binary phase computer generated hologram in the discrete cosine transform(OCT) domain. For the embedding process of watermark, using simulated annealing algorithm, we would generate a binary phase computer generated hologram(BPCGH) which can reconstruct hidden image perfectly instead of hidden image and repeat the hologram and encrypt it through the XOR operation with key image that is ramdomly generated binary phase components. We multiply the encrypted watermark by the weight function and embed it into the DC coefficients in the DCT domain of host image and an inverse DCT is performed. For the extracting process of watermark, we compare the DC coefficients of watermarked image and original host image in the DCT domain and dividing it by the weight function and decrypt it using XOR operation with key image. And we recover the hidden image by inverse Fourier transforming the decrypted watermark. Finally, we compute the correlation between the original hidden image and recovered hidden image to determine if a watermark exits in the host image. The proposed watermarking technique use the hologram information of hidden image which consist of binary values and encryption technique so it is very secure and robust to the external attacks such as compression, noises and cropping. We confirmed the advantages of the proposed watermarking technique through the computer simulations.

• The KIPS Transactions:PartD
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• v.17D no.6
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• pp.463-470
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• 2010

We presented a very fast and robust method of text line segmentation based on the DCT blocks of color image without decompression and binary transformation processes. Using DC and another three primary AC coefficients from block DCT we created a gray-scale image having reduced size by 8x8. In order to detect and locate white strips between text lines we analyzed horizontal and vertical projection profiles of the image and we applied a direct markov model to recover the missing white strips by estimating hidden periodicity. We presented performance results. The results showed that our method was 40 - 100 times faster than traditional method.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.31 no.6C
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• pp.637-644
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• 2006

This paper presents performance and implementation comparisons of standard and fast DCT algorithms that are commonly used for subband filter bank in MPEG audio coders. The comparison is made according to the architectural difference of the implementation hardware. Fast DCT algorithms are known to have much less computational complexity than the standard method that involves computing a vector dot product of cosine coefficient. But, due to structural irregularity, fast DCT algorithms require extra cycles to generate the addresses for operands and to realign interim data. When algorithms are implemented using DSP processors that provide special operations such as single-cycle MAC (multiply-accumulate), zero-overhead nested loop, the standard algorithm is more advantageous than the fast algorithms. Also, in case of the finite-precision processing, the error performance of the standard method is far superior to that of the fast algorithms. In this paper, truncation errors and algorithmic suitability are analyzed and implementation results are provided to support the analysis.

• Proceedings of the Korean Information Science Society Conference
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• 1999.10b
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• pp.497-499
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• 1999

본 논문에서는 다양한 부품에 대한 적당한 분류 방법을 찾기 위해 일반적으로 많이 사용되는 신경망을 이용하는 분류 방법과 템플리트 매칭을 이용한 분류 방법을 실험에 사용하였다. 본 연구에서는 부품 분류 방법을 부품의 분류율과 인식에 사용될 수 있는 최대 부품 수를 고려하여 비교 분석하였다. 실험결과 DCT(Discrete Cosine Transform)를 이용한 템플리트 매칭 방법이 다양한 부품을 인식하는데 있어 가장 뛰어난 분류율을 보였다.

• Proceedings of the IEEK Conference
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• 2003.07b
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• pp.835-838
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• 2003

본 논문에서는 현재 MPEG, JPEG 압축 알고리즘에서 쓰이는 DCT(Discrete Cosine Transform)기반의 손실 영상 압축에 사용되는 양자화(Quantization) 처리에 필요한 나눗셈 연산기를 제안한다. 영상 데이터 처리를 위한 양자화기(Quantizer)는 DCT로부터 매 사이클마다 영상 데이터를 입력 받아 양자화 처리를 해야하며 보다 나은 영상 데이터를 위해 최종 나눗셈 결과 즉, 몫을 소수 첫째자리에서 반올림(Rounding)해야 한다. 이를 위해 반올림 동작이 추가된 Pipelined Nonrestoring Array Divider를 설계하였다. 제안된 방법의 타당성을 검증하기 위해 DCT로부터 나온 영상 데이터를 제안된 구조의 양자화기로 양자화하여 일반 양자화기에서 나온 압축된 데이터와 비교해 보았다. 또한 합성기(Synthesis)를 통하여 실제 하드웨어 크기를 분석하였다.

• Proceedings of the Korean Information Science Society Conference
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• 1998.10c
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• pp.476-478
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• 1998

본 논문에서는 영상의 밝기 정보로부터 물체의 표면 형상을 재구성하는 새로운 접근 방법을 제시한다. 이미지 모델은 기존의 Lambertian surface model에 거리 요소를 포함시켜 보다 현실과 비슷한 제약 조건을 주고, 국지 해(local minima)에 빠지기 쉬운 기존의 iteration 방법을 탈피하기 위해 유전자 알고리즘(genetic algorithm)을 도입한다. 표면의 깊이 정보를 이산여현변환(discrete cosine transform)하고 이 DCT 공간상에서 유전자 알고리즘을 적용함으로써 큰 형상을 먼저 결정한 후 미세한 형상을 찾아내는 계층적인 표면 형상의 재구성이 가능하도록 하였으며 간단한 실험으로 그 타당성을 보인다.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 1995.06a
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• pp.105-108
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• 1995

본 논문에서는 초기 비트율 부호화(very low bit-rate coding)를 위한 새로운 움직임 예측 부호화를 제안한다. 움직임 추정 및 움직임 보상은 영역 기반으로 행해지며, 움직임 보상 후 예측 오차는 DCT(Discrete Cosine Transform)를 통해 변환되어 부호화 된다. 제안된 내용으로는 이전 영상을 이용하여 역방향(backward) 움직임 추정 후 얻어지는 움직임 벡터를 이용하여 움직임 보상된 영상을 구성하고, 여기에 보상되지 않은 영역은 순방향(forward) 움직임 추정을 선택적으로 행함으로써 영상을 재구성한다. 제안된 알고리듬은 모의 실험 결과 양질의 화질을 얻었다.