• Journal of the Korean Institute of Telematics and Electronics B
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• v.30B no.7
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• pp.14-23
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• 1993

This paper proposes an algorithm to reduce the bitrate for transmission of MCP(motion compensated prediction) error signals. Many digital image coders have recently employed hybrid coding schemes which perform motion compensation, DCT transform, quantization, and variable length coding. The variable length coding compresses the quantized DCT coefficient data by removing their statistical redundancy. But some DCT blocks have the interblock statistical redundancy as well as the intrablock one. To utilize both of them, the DCT blocks are classified into the interleaving group and the non-interleaving group. And then each DCT blocks in the interleaving group are is encoded independently, and the DCT blocks in the interleaving group are encoded after interleaving the DCT coefficients. Through the simulations, it is shown that the proposed method outperforms the conventional method in which each DCT block is encoded independently.

• Journal of the Korea Computer Graphics Society
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• v.15 no.3
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• pp.11-18
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• 2009

In this paper, we introduce a novel method to extend the JPEG standard, which is the most widely used for lossy image compression, in order to improve compression ratio. To employ two of the most successful methodologies for the data compression: differential coding and quantization simultaneously, we propose a line-based approach. For each line in a block, we apply one-dimensional discrete cosine transformation to the increments instead of the pixel values. Those values are quantized and entropy-coded similarly to the JPEG standard. To further increase compression ratio, the proposed method is plugged into the JPEG standard to form a new compression method, in which the proposed method are applied to only selected JPEG blocks. In our experiment, we found that the proposed method outperform the JPEG standard when the qualities of the coded images are set to be high. We believe the proposed method can be simply plugged into the standard to improve its compression ratio for higher quality images.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.24 no.12B
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• pp.2382-2390
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• 1999

In this paper, we employed a new quantization scheme called sample-adaptive product quantizer (SAPQ) to quantize image data based on the differential pulse code modulation (DPCM) coder, which has fixed length outputs and high bit rates. In order to improve the performance of traditional DPCM coders, the scalar quantizer should be replaced by the vector quantizer (VQ). As the bit rate increases, it will be nearly impossible to implement a conventional VQ or modified VQ, such as the tree-structured VQ, even if the modified VQ can significantly reduce the encoding complexity. SAPQ has a form of the feed-forward adaptive scalar quantizer having a short adaptation period. However, since SAPQ is a structurally constrained VQ, SAPQ can achieve VQ-level performance with a low encoding complexity. Since SAPQ has a scalar quantizer structure, by using the traditional scalar value predictors, we can easily apply SAPQ to DPCM coders. For synthetic data and real images, by employing SAPQ as the quantizer part of DPCM coders, we obtained a 2~3 dB improvement over the DPCM coders, which are based on the Lloyd-Max scalar quantizers, for data rates above 4 b/point.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.48 no.10
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• pp.6-14
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• 2011

This paper presents the design of the battery sensor IC for instrumentation of current, voltage using delta-sigma ADC. The proposed circuit consists of programmable gain instrumentation amplifier (PGIA) and second-order discrete-time delta-sigma modulator with 1-bit quantization were fabricated by a 0.25 ${\mu}m$ CMOS technology. Design circuit show that the modulator achieves 82 dB signal-to-noise ratio (SNR) over a 2 kHz signal bandwidth with an oversampling ratio (OSR) of 256 and differential nonlinearity (DNL) of ${\pm}$ 0.3 LSB, integral nonlinearity (INL) of ${\pm}$ 0.5 LSB. Power consumption is 4.5 mW.

• Journal of the Institute of Electronics and Information Engineers
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• v.49 no.10
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• pp.148-158
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• 2012

This paper presents the design of the incremental delta-sigma ADC. The proposed circuit consists of pre-amplifier, S & H circuit, MUX, delta-sigma modulator, and decimation filter. Third-order discrete-time delta-sigma modulator with 1-bit quantization were fabricated by a $0.18{\mu}m$ CMOS technology. The designed circuit show that the modulator achieves 87.8 dB signal-to-noise and distortion ratio (SNDR) over a 5 kHz signal bandwidth and differential nonlinearity (DNL) of ${\pm}0.25$ LSB, integral nonlinearity (INL) of ${\pm}0.2$ LSB. Power consumption of delta-sigma modulator is $941.6{\mu}W$. It was decided that N cycles are 200 clock for 16-bits output.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.36 no.11C
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• pp.655-661
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• 2011

The transmission issues for the scalable video coding extension of H.264/AVC (H.264 SVC) video has been widely studied. In this paper, we propose an objective video-quality assessment metric based on no-reference for H.264 SVC using scalability information. The proposed metric estimate the perceptual video-quality reflecting error conditions with the consideration of the motion vectors, error propagation patterns with the hierarchical prediction structure, quantization parameters, and number of frame which damaged by packet loss. The proposed metric reflects the human perceptual quality of video and we evaluate the performance of proposed metric by using correlation relationship between differential mean opinion score (DMOS) as a subjective quality and proposed one.

• Journal of Astronomy and Space Sciences
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• v.31 no.2
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• pp.121-130
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• 2014

Essential ideas, successes, and difficulties of Areal Density Analysis (ADA) for color-magnitude diagrams (CMD's) of resolved stellar populations are examined, with explanation of various algorithms and strategies for optimal performance. A CMD-generation program computes theoretical datasets with simulated observational error and a solution program inverts the problem by the method of Differential Corrections (DC) so as to compute parameter values from observed magnitudes and colors, with standard error estimates and correlation coefficients. ADA promises not only impersonal results, but also significant saving of labor, especially where a given dataset is analyzed with several evolution models. Observational errors and multiple star systems, along with various single star characteristics and phenomena, are modeled directly via the Functional Statistics Algorithm (FSA). Unlike Monte Carlo, FSA is not dependent on a random number generator. Discussions include difficulties and overall requirements, such as need for fast evolutionary computation and realization of goals within machine memory limits. Degradation of results due to influence of pixelization on derivatives, Initial Mass Function (IMF) quantization, IMF steepness, low Areal Densities ($\mathcal{A}$), and large variation in $\mathcal{A}$ are reduced or eliminated through a variety of schemes that are explained sufficiently for general application. The Levenberg-Marquardt and MMS algorithms for improvement of solution convergence are contained within the DC program. An example of convergence, which typically is very good, is shown in tabular form. A number of theoretical and practical solution issues are discussed, as are prospects for further development.

• Journal of the Korean Institute of Telematics and Electronics S
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• v.36S no.7
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• pp.116-123
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• 1999

of a block if the method uses the quantization parameter depending on the bitrate control, and consequently it influence the image quality of video. In this paper, we propose a new method using the following three steps : calculating an averaging (Average of Sum, AS) value in each pixel's block of images, earning an average value of differences between each pixels and As (Differential Averaging Block Pixels, DABP), and finally achieving an improved coefficient values by the DABP and DCT coefficients. Simulation results show that the quality of moving picture could be improved by the proposed method.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.39A no.12
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• pp.746-755
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• 2014

Compressive sensing (CS) has drawn much interest as a new sampling technique that enables signals to be sampled at a much lower than the Nyquist rate. By noting that the block-based compressive sensing can still keep spatial correlation in measurement domain, in this paper, we propose a novel encoding technique for measurement data obtained in the block-based CS of natural image. We apply discrete wavelet transform (DWT) to decorrelate CS measurements and then assign a proper quantization scheme to those DWT coefficients. Thus, redundancy of CS measurements and bitrate of system are reduced remarkably. Experimental results show improvements in rate-distortion performance by the proposed method against two existing methods of scalar quantization (SQ) and differential pulse-code modulation (DPCM). In the best case, the proposed method gains up to 4 dB, 0.9 dB, and 2.5 dB compared with the Block-based CS-Smoothed Projected Landweber plus SQ, Block-based CS-Smoothed Projected Landweber plus DPCM, and Multihypothesis Block-based CS-Smoothed Projected Landweber plus DPCM, respectively.

• Journal of Korea Multimedia Society
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• v.15 no.4
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• pp.492-500
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• 2012

In this paper, improved contour region coding method is proposed to accomplish better depth map coding performance. First of all, in order to use correlation between color video and depth map, a structure in SVC is applied to 3DVC. This can reduce bit-rate of the depth map while supporting the video to be transferred via various collection of network. As the depth map is mainly used to synthesize videos from different views, corrupted contour region can damage the overall quality of video. We hereby adapt a new differential quantization method when separating the contour region. The experimental results show that the proposed method can improve video quality by 0.06~0.5dB which translate the bit rate saving by 0.1~1.15%, when compared to the reference software.