• Journal of Broadcast Engineering
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• v.15 no.3
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• pp.355-361
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• 2010

Video Compression is the key technology for the transmission of multi-media data. Because the Motion Estimation is the most complex module in the video compression, fast motion estimation algorithm is essential for the real-time application. In this paper, we propose an enhanced binary motion estimation algorithm based on the wavelet transform. Proposed algorithm improve the quality of coded video.

• Proceedings of the IEEK Conference
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• 2002.07c
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• pp.1424-1427
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• 2002

This paper proposes a novel postprocessing algorithm for reducing the blocking artifacts in low bit rate block-based transform coded images, that use adaptive neural network filter (NNF) in wavelet transform domain. n this algorithm, after performing a 2-level wavelet transform of the decompressed image, the existence of locking artifacts is determined using statistical characteristic of neighborhood blocks. And then a different one-dimensional (1-D) or 2-D NNF is used to reduce the locking artifacts according to the classified regions. That is, for HL and LH subbands regions with the blocking artifacts, a different 1-D NNF is used. And 2-D NNF is used in HH subband. Experimental results show that the proposed algorithm produced better results than those of conventional algorithms both subjectively and objectively.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.34 no.1C
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• pp.105-112
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• 2009

In this paper, we propose a digital watermarking method using Multi-resolution Characteristic of 2D CAT (2D cellular automata transform). Firstly, we select the gateway values to generate a basis function and the basis function transforms images into cellular automata space. Then, we embed the random bit sequence as watermark in specific parts of cellular automata transform coefficients. The proposed method not only verifies higher fidelity than the existing method but also stronger stability on JPEG lossy compression, filtering, sharpening and noise through tests for robustness. Moreover, the proposed scheme allows only one 2D CAT basis function per gateway value. Since there are $2^{96}$ possible gateway values.

• Proceedings of the KOSOMBE Conference
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• v.1992 no.05
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• pp.58-63
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• 1992

The discrete cosine transform (DCT)-based progressive coding standard proposed by the International Standardization Orgnnization (ISO) Joint Photographic Experts Groups (JPEG) is investigated for medical image compression and the performance of the JPEG is compared to that of the full-frame bit-allocation (FFBA) technique. From the comparison, the JPEG standard appeals superior to the FFBA technique in the following aspects: 1) JPEG achieves higher compression than the FFBA technique with less mean square error. 2) Less Gibb's artifact is observed in the compressed images by the JPEG. 3) Computational time for the JPEG is about one-fourth or the FFBA technique. Other attractive points of the JPEG include: Implementation of the JPEG with VLSIs is commercially available in relative low price and the JPEG compression format can easily be interchangeable with other applications.

• Proceedings of the IEEK Conference
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• 2002.07a
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• pp.277-280
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• 2002

Many digital watermarking methods have been proposed for copyright protection. Especially, methods to add a watermark in the frequency domain are often used. In those methods, only a few components of frequencies are changed according to watermark information, so that the pixel values of the image obtained by the inverse transform sometimes exceed the dynamic range and owing to the clipping process at this time watermark information is changed. This phenomenon even occurs without attacks like image processing. In this paper, we propose two methods to prevent loss of watermark information, applicable to such cases, it is said that one is the method called "inversion of increase and decrease" and another is "conservation of amounts of changes." We can extract the watermark information correctly under the condition of no attacks by using these proposed methods.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.33 no.3C
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• pp.234-239
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• 2008

For the efficient coding and transmission, the speech signal can be classified into three distinctive classes: voiced, unvoiced, and transition classes. At low bit rate coding below 4 kbit/s, conventional sinusoidal transform coders synthesize speech of high quality for the purely voiced and unvoiced classes, whereas not for the transition class. The transition class including plosive sound and abrupt voiced-onset has the lack of periodicity, thus it is often classified and synthesized as the unvoiced class. In this paper, the efficient algorithm for the transition class detection is proposed, which demonstrates superior detection performance not only for clean speech but for noisy speech. For the detected transition frame, phase information is transmitted instead of magnitude information for speech synthesis. From the listening test, it was shown that the proposed algorithm produces better speech quality than the conventional one.

• Journal of the Korean Institute of Telematics and Electronics B
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• v.31B no.10
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• pp.130-139
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• 1994

Video compression algorithms are based on removing spatial and/or temproal redundancy inherent in image sequences by predictive(DPCM) encoding, transform encoding, or a combination of predictive and transform encoding. In this paper, each 8$\times$8 DCT coefficient of DFD(displaced frame difference) is adaptively quantized by one of the four quantizers depending on total distortion level, which is determined by characteristics of HVS(human visual system) and buffer status. Therefore, the number of possible quantizer selection vectors(patterns) is 4$^{64}$. If this vectors are coded, toomany bits are required. Thus, the quantizer selection vectors are limited to 2048 for Y and 512 for each U, V by the proposed method using SWAD(sum of weighted absolute difference) for discriminating vectors. The computer simulation results, using the codebook vectors which are made by the proposed method, show that the subjective and objective image quality (PSNR) are goor with the limited bit allocation. (17Mbps)

• International Journal of Fuzzy Logic and Intelligent Systems
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• v.14 no.4
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• pp.249-255
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• 2014

We present a simple method to watermark three-dimensional (3D) triangular meshes that have been generated from the depth data of the Kinect sensor. In contrast to previous methods, which maintain the shape of 3D triangular meshes and decide the embedding place, requiring calculations of vertices and their neighbors, our method is based on selecting one of the coordinate axes. To maintain shape, we use discrete wavelet transform and constant regularization. We know that the watermarking system needs the information to be embedded; we used a text to provide that information. We used geometry attacks such as rotation, scales, and translation, to test the performance of this watermarking system. Performance parameters in this paper include the vertices error rate (VER) and bit error rate (BER). The results from the VER and BER indicate that using a correction term before the extraction process makes our system robust to geometry attacks.

• Journal of the Institute of Electronics Engineers of Korea SP
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• v.41 no.3
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• pp.25-34
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• 2004

The ability to perform the same operations in the transform domain as in the spatial domain is important for efficient image transmission through a channel. We perform image resizing, which includes magnifying and reducing the size, in the discrete cosine transform(DCT) domain and the effects of the transform domain approach are analyzed in the corresponding spatial domain. Based on this analysis, the two resizing algorithms are proposed. The first one further compresses the images encoded by the compression standard by reducing the size before compression, and the other reduces the loss of information while maintaining the conventional compression rate. Because of its compatibility with standard codec, these algorithms can be easily embedded in JPEG and MPEG codecs, which are widely used for the purpose of image storage and transmission. Experimental results show a reduction of about half the bit size with similar image quality and about a 2- or 3-dB quality improvements in the similar compression rate.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.32 no.3C
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• pp.256-268
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• 2007

In this paper, we present a watermarking method for 3-D mesh sequences. The main idea is to transform vertex norm with the identical connectivity index along temporal axis using wavelet transform and modify the distribution of wavelet coefficients in temporally high (or middle) frequency frames according to watermark bit to be embedded. All vertices are divided into groups, namely bin, using the distribution of coefficients in low frequency frames. As the vertices with the identical connectivity index over whole frames belong to one bin, their wavelet coefficients are also assigned into the same bin. Then, the watermark is embedded into the wavelet coefficients of vertex norm. Due to the use of the distribution, our method can retrieve the hidden watermark without any information about original mesh sequences in the process of watermark detection. Through simulations, we show that the proposed is flirty robust against various attacks that are probably concerned in copyright protection of 3-D mesh sequences.