• Journal of the Korean Institute of Telematics and Electronics B
• /
• v.28B no.5
• /
• pp.318-326
• /
• 1991

A Quantizer reconstruction level control method for block artifact reduction in DCT image coding is described. In our scheme, quantizer reconstruction level control is obtained by adding quantization level step size to the optimum quantization level in the direction of reducing the block artifact by minimizing the mean square error(MSE) and error difference(EDF) distribution in boundary without the other additional bits. In simulation results, although the performance in terms of signal to noise ratio is degraded by a little amount, mean square of error difference at block boundary and mean square error having relation block artifact is greatly reduced. Subjective image qualities are improved compared with other block artifact reduction method such as postprocessing by filtering and trasform coding by block overlapping. But the addition calculations of 1-dimensional DCT become to be more necessary to coding process for determining the reconstruction level.

• Korean Journal of Digital Imaging in Medicine
• /
• v.10 no.1
• /
• pp.13-19
• /
• 2008

Purpose : In sponge quality of the material in digital radiography environment coating because do position blocks two that do not become coating done positioning blocks two that do not become coating done positioning block and sponge quality of the material to testing bench image artifact's difference compare. Method of study : In digital radiography environment positioning block of different two products same sunshine or effect that image and positioning block artifact gents in image analyze. the target used positioning block 2 when examine hand, rib and examination condition did each differently according to used positioning block. reflex compared picture that do image and verify that examine first time. Result : 1. In sponge quality of the material coating in done product artifact appear. Did not appear in product that do not become coating. 2. Can know coating's existence, that artifact according to radish happens. 3. Quality of the material coating's existence, there was difference of slippage according to radish Conclusion : Quality of the material coating phenomenon that done positioning block thus, it may have to be considered that use after estimate degree that get in image.

• Proceedings of the IEEK Conference
• /
• 1998.10a
• /
• pp.907-910
• /
• 1998

In this paper, we present a comparative performance analysis of several blocking artifact reduction algorithms. For the performance analysis, we propose a block boundary region classification algorithm which classifies each horizontal and vertical block boundary into four regions using brightness change near the block boundary. The PSNR performance of each algorithm is compared. The MSE according to each block boundary region is also compared. Experimental results show that the wavelet transform based blocking artifact reduction algorithms have better performance over the other methods.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.24 no.10B
• /
• pp.1921-1936
• /
• 1999

In this paper, we analyze the blocking artifact in block transform-coded images and propose a classification algorithm which classifies each horizontal and vertical block boundary into four regions of EQ, BA, EE, and AE according to the characteristics of the blocking artifact. We also compare the performance of several blocking artifact reduction methods which can reduce blocking artifact in block transform-coded images well. As the blocking artifact reduction methods, the LOT, Kim's wavelet transform-based method, Yang's POCS, Paek's POCS, and Jang's CM have been selected. Experimental results show that each horizontal and vertical block boundary classified by using the proposed classification algorithm yields different characteristics of discontinuities due to the blocking artifact according to the classified region. It is also shown that the blocking artifact reduction methods using wavelet transform yield better performance over the other methods.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.27 no.6A
• /
• pp.584-591
• /
• 2002

In this paper, we proposed a b1ocking artifact reduction algorithm using similarity and linear combination between blocks. In the proposed method, all of the blocks are classified into low frequency block and high frequency block according to the their DCT coefficients. And we defined range block which shows blocking artifacts, as block centered to block boundary and defied domain block as similar block with range block within search range. In the search procedure, we used sub-block's property of range block and similarity for more accurate searching. Finally blocking artifact reduction algorithm is performed using linear combination between searched domain block and blocky range block. The performance of the proposed method is investigated by computer simulation in comparison with the traditional methods. In the experimental results, Ire confirmed the better performance in the subjective by 0.04∼0.4 dB and objective image quality.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.11 no.9
• /
• pp.1650-1657
• /
• 2007

In this paper, we propose an Overlapped Block and an Hanning Window to prevent a Block Discontinuity when we use an algorithm to eliminate ringing artifact which is based on a block structure. The algorithm to eliminate ringing artifact operates with a block structure and 24-RGB data and is based on a modified K-means algorithm. The proposed overlapped block method is piled up one on another per an half of the size of unit-block when an input image is split into several unit-blocks. Therefore, we define a data unit as the unit-block of the block size, $16{\times}16$ pixels. We reconstruct the processed data units into the original form of input image by using an isotropic form of Hanning Window. Finally, in order to evaluate the performance of the abovementioned algorithms, we compare three image, an input image with ringing artifact, an image result obtained by conventional method (non-overlapped), and an image result obtained the proposed method.

• Journal of the Korea Computer Graphics Society
• /
• v.6 no.3
• /
• pp.35-40
• /
• 2000

There are two problems in H.26X compression technique. One is compressing time in encoding process and the other is degradation of the decoded video quality due to high compression rate. For transferring moving pictures in real-time, it is required to adopt massively high compression. In this case, there are a lot of losses of an original video data and that results in degradation of quality. Especially degradation called by blocking artifact may be produced. The blocking artifact effect is produced by DCT-based coding techniques because they operate without considering correlation between pixels in block boundaries. So it represents discontinuity between adjacent blocks. This paper describes methods of quality compensation for H.26x decoded data and enhancing encoding speed for real-time operation. Our goal of the quality compensation is not to make the decoded video identical to a original video but to make it perceived better through human eyes. We suggest an algorithm that reduces block artifact and clears decoded video in decoder. To enhance encoding speed, we adopt new four-step search algorithm. As shown in the experimental result, the quality compensation provides better video quality because of reducing blocking artifact. And then new four-step search algorithm with $MMX^{TM}$ implementation improves encoding speed from 2.5 fps to 17 fps.

• Journal of the Institute of Electronics Engineers of Korea CI
• /
• v.48 no.1
• /
• pp.60-64
• /
• 2011

In this paper, we propose a new post-processing technique that removes blocking and ringing artifacts in Block discrete cosine transformation (BDCT)-coded images using bilateral filtering. The selection of filter parameters is a key issue in the application of a bilateral filter because it significantly affects the result. An efficient method of selecting the bilateral filter parameters is presented. The experimental results show that the proposed approach alleviates the artifacts efficiently in terms of PSNR, MSDS, and SSIM.

• Proceedings of the IEEK Conference
• /
• 2000.07a
• /
• pp.437-440
• /
• 2000

This paper proposes a method to improve video quality on images that have blocking artifacts at block boundary. Block image transform coding suffers from blocking artifact that is a main cause of degrading video quality because of the quantization error of transform coefficients in quantization process. filtering and DPCM for DC components have been widely used to reduce blocking artifact. Recently, lots of works focus on the technique that minimizes block effects using discontinuity of block boundaries. In this paper, image blurring in decoding stage is improved by adding compensation factor to each transformed blocks so that discontinuity of block boundaries can be decreased. The compensation factor is applied on each block without much loss of edge components.

• Journal of Korea Society of Industrial Information Systems
• /
• v.12 no.1
• /
• pp.39-45
• /
• 2007

In this paper, we present a new postprocessing algorithm using interpolation and signal adaptive filter according to the each block characteristic which is acquired in block classification process. We applied blocking artifact reduction algorithm for four neighbor low frequency block and ringing artifacts is removed with preserving edges by applying a signal adaptive filter in high frequency block based on edge map. The computer simulation results confirmed a better performance by the proposed method in both the subjective and objective image qualities.