• 방송공학회논문지
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• 제16권6호
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• pp.962-968
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• 2011

기존의 무손실 압축은 일반적으로 채널간의 상관관계를 고려하지 않고 각각의 채널을 따로 압축하였다. 채널 간 상관관계를 이용하는 경우도 있으나 이들은 위성/항공 영상과 같은 경우에 제한된 것으로서 일반적인 이미지에 대해서는 만족할만한 성능을 얻지 못하였다. 본 논문에서는 컬러 이미지가 갖는 채널 간의 상관관계를 이용하여 무손실 압축의 성능을 향상시키는 방법을 제안하였다. 제안된 방법에서는 채널 간 상관관계를 표현할 수 있도록 하기 위하여, 비대칭 샘플링을 통해 주어진 영상의 모자이크 이미지를 구성하여 압축을 수행하였고, 압축된 모자이크 이미지의 정보를 이용해서 샘플링되지 않은 나머지 이미지를 예측하여 압축할 정보의 양을 감소시켰다. 제안된 방법은 압축 성능을 평가하는데 일반적으로 사용되는 데이터들에 대해서 채널 간 상관관계를 이용하지 않는 방법에 대해 35%, 채널 간 상관관계를 이용한 기존 방법에 대해 10%의 성능 개선을 보인다.

• 대한의용생체공학회:의공학회지
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• 제12권2호
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• pp.99-106
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• 1991

For the automatic detection of pulmonary blood vessels, a new algorithm is proposed using the fact that human recognizes a pattern orderly according to their size. This method simulates the human recognition process by the pyramid images. For the detection of vessels using multilevel image, large and wtde ones are detected from the most compressed level, followed by the detection of small and narrow ones from the less compressed images with FCM(fuzzy c means) clustering algorithm which classifies similar data into a group. As the proposed algorithm detects blood vessels orderly according to their size, there is no need to consider the variation of parameters and the branch points which should be considered in other detection algirithms. In the detection of patterns whose size changes successively like pulmonary blood vessels, this proposed algorithm can be properly applied

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제14권6호
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• pp.2554-2575
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• 2020

Data hiding technology hides secret information into the carrier, so that when the carrier is transmitted over network, it will not attract any malicious attention. Using data compression, it is possible to reduce the data size into a small compressed code, which can effectively reduce the time when transmitting compressed code on the network. In this paper, the main objective is to effectively combine these two technologies. We designed a data hiding scheme based on two techniques which are turtle-shell information hiding scheme and absolute moment block truncation coding. The experimental results showed that the proposed scheme provided higher embedding capacity and better image quality than other hiding schemes which were based on absolute moment block truncation coding.

• 대한디지털의료영상학회논문지
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• 제16권1호
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• pp.1-5
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• 2014

This study is about efficiency export and import of medical images According to the Type of Compression. PACS to be used in many hospitals and medical images export is growing more and more because cheaper and good usability than film system. Thereby export department takes a lot of time, which may cause the patient discomfort. Compression images takes less time for images export, import than nocompression images. therefore, if no significant problems clinicians to view the images, this is one method to compressed images export for reduce the time and it will provide less cost and shorter time for patient.

• 대한전기학회논문지:시스템및제어부문D
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• 제53권6호
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• pp.453-456
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• 2004

Due to the bandwidth and storage limitations medical images are needed to be compressed before transmission and storage. DICOM (Digital Imaging and Communications in Medicine) specification, which is the medical images standard, provides a mechanism for supporting the use of JPEG still image compression standard. In this paper, we explain a method for compressing medical images by PEG standard and propose two methods for JPEG compression. First, because medical images differ from natural images in optical feature, we propose a method to design adaptively the quantization table using spectrum analysis. Second, because medical images have higher pixel depth than natural images do, we propose a method to design Huffman table which considers the probability distribution feature of symbols. Simulation results show the improved performance compared to the quantization table and the adjusted Huffman table of JPEG standard.

• 방송공학회논문지
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• 제4권2호
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• pp.155-163
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• 1999

본 논문은 새로운 장면 전환 검출과 키 프레임 선태 기법을 제안하였다. 이를 위해 본 논문에서는 MPEG 압축 동영상에서 직접 DC 영상 및 에지(edge) 영상을 추출하여 이용하는데, 공간 영역으로 변환 후 에지 연상을 추출할 경우 계산량이 많다는 문제점이 있다. 따라서 본 논문에서는 그 계산량을 줄이기 위해 DCT 블록 당 5개의 저 대역 AC 계수들만을 이용하여 축소된 에지 영상을 고속으로 추출하는 방법을 제안하고, 이를 바탕으로 AC 예측(prediction)을 이용한 고속 에지 추출 기법도 추가적으로 제안하였다. 화질 측면에서 전자가 후자보다 약간 우수하지만, 두 방법 모두 영상의 중요한 에지 특징들을 잘 추출할 수 있다. 이와 같이 얻어진 에지 영상 및DC 영상을 이용하여 에지 에너지 다이어그램(dege energy diagram)과 히스토그램(histogram)을 구하여 급진적인 장면 전환 및 페이드(fade), 디졸브(dissolve) 같은 점진적인 장면 전환을 정확하게 검출함을 모의 실험을 통해 확인하였다. 또한 공간 영역에서 구한 에지 영상들에 비해 제안한 방법들에 의한 에지 영상들이 점진적인 장면 검출에 있어 훨씬 적은 계산량으로 비슷한 성능을 보임을 확인하였다. 마지막으로 HVS(human visual system)에 기반하여 각 장면에서 키 프레임을 선택하는 방법도 제안하였다. 위에서 얻어진 에지 및 DC 영상을 이용하기 때문에 optical flow를 이용하는 기존 방법에 비해 적은 계산량으로 의미 있는 키 프레임을 선택할 수 있었다.

• 한국멀티미디어학회논문지
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• 제23권8호
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• pp.1019-1029
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• 2020

In this paper, we propose a novel knowledge distillation algorithm to create an compressed deep ensemble network coupled with the combined use of local and global features of face images. In order to transfer the capability of high-level recognition performances of the ensemble deep networks to a single deep network, the probability for class prediction, which is the softmax output of the ensemble network, is used as soft target for training a single deep network. By applying the knowledge distillation algorithm, the local feature informations obtained by training the deep ensemble network using facial subregions of the face image as input are transmitted to a single deep network to create a so-called compressed ensemble DCNN. The experimental results demonstrate that our proposed compressed ensemble deep network can maintain the recognition performance of the complex ensemble deep networks and is superior to the recognition performance of a single deep network. In addition, our proposed method can significantly reduce the storage(memory) space and execution time, compared to the conventional ensemble deep networks developed for face recognition.

• 한국멀티미디어학회논문지
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• 제7권12호
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• pp.1745-1753
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• 2004

A method of estimating the pose of a three-dimensional object from a set of two-dimensioal images based on parametric eigenspace method is proposed. A Gaussian blurred edge image is used as an input image instead of the original image itself as has been used previously. The set of input images is compressed using K-L transformation. By comparing the estimation errors for the original, blurred original, edge, and blurred edge images, we show that blurring with the Gaussian function and the use of edge images enhance the data compression ratio and decrease the resulting from smoothing the trajectory in the parametric eigenspace, thereby allowing better pose estimation to be achieved than that obtainable using the original images as it is. The proposed method is shown to have improved efficiency, especially in cases with occlusion, position shift, and illumination variation. The results of the pose angle estimation show that the blurred edge image has the mean absolute errors of the pose angle in the measure of 4.09 degrees less for occlusion and 3.827 degrees less for position shift than that of the original image.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제15권9호
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• pp.3298-3321
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• 2021

A lot of data hiding schemes have been proposed to embed secret data in the plain cover images or compressed images of various formats, including JPEG, AMBTC, VQ, etc. In this paper, we propose a production process of mosaic images based on three regular images of coffee beans. A primary image is first mimicked by the process to produce a mosaic cover image. A two-layer steganography is applied to hide secret data in the mosaic image. Based on the low visual quality of the mosaic cover image, its PSNR value can be improved about 1.5 dB after embedding 3 bpp. This is achieved by leveraging the newly proposed polarized search mask and the concepts of strong embedding and weak embedding. Applying steganography to the mosaic cover images is a completely new idea and it is promising.

• Imaging Science in Dentistry
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• 제30권4호
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• pp.265-274
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• 2000

Purpose: The aims of the present study are to determine the optimum compression rate in terms of file size reduction and diagnostic quality of the images after compression and evaluate the transmission speed of original or each compressed image. Materials and Methods: The material consisted of 24 extracted human premolars and molars. The occlusal surfaces and proximal surfaces of the teeth had a clinical disease spectrum that ranged from sound to varying degrees of fissure discoloration and cavitation. The images from Digora system were exported in TIFF and the images from conventional intraoral film were scanned and digitalized in TIFF by Nikon SF-200 scanner (Nikon, Japan). And six compression factors were chosen and applied on the basis of the results from a pilot study. The total number of images to be assessed were 336. Three radiologists assessed the occlusal and proximal surfaces of the teeth with 5-rank scale. Finally diagnosed as either sound or carious lesion by one expert oral pathologist. And sensitivity, specificity and k value for diagnostic agreement was calculated. Also the area (Az) values under the ROC curve were calculated and paired t-test and oneway ANOVA test was performed. Thereafter, transmission time of the image files of the each compression level was compared with that of the original image files. Results: No significant difference was found between original and the corresponding images up to 7% (1 : 14) compression ratio for both the occlusal and proximal caries (p<0.05). JPEG3 (1 : 14) image files are transmitted fast more than 10 times, maintained diagnostic information in image, compared with original image files. Conclusion: 1 : 14 compressed image file may be used instead of the original image and reduce storage needs and transmission time.