• Journal of the Korean Society for Precision Engineering
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• v.21 no.4
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• pp.95-102
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• 2004

It is necessary to improve the exactness and adaptation of the working environment in the intelligent robot system. The vision sensor have been studied for this reason fur a long time. However, it is very difficult to perform the camera and robot calibrations because the three dimensional reconstruction and many processes are required for the real usages. This paper suggests the image based visual servoing to solve the problem of old calibration technique and supports OLP(Off-Line-Programming) path compensation. Virtual camera can be modeled from the real factors and virtual images obtained from virtual camera gives more easy perception process. Also, Initial path generated from OLP could be compensated by the pixel level acquired from the real and virtual, respectively. Consequently, the proposed visually assisted OLP teaching remove the calibration and reconstruction process in real working space. With a virtual simulation, the better performance is observed and the robot path error is calibrated by the image differences.

• Journal of Digital Contents Society
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• v.8 no.1
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• pp.85-91
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• 2007

This paper proposes a new hybrid anti-aliasing method for reducing aliasing appearing on an implicit surface using the point sampling. The hybrid anti-aliasing method is a method that finds differences in the values of pixel shown in Z-buffers for an implicit surface and thereby uses each of three types of Z-buffer. After determining the level of differences, it expresses a 3 dimensional object by using a multi Z-buffer if the level is severe, a double Z-buffer for a middle level, and only the original Z-buffer for a negligible difference. In comparison with the existing method in which multi Z-buffers have been entirely used for enhancing the anti-aliasing effect, the hybrid anti-aliasing method is an efficient method demonstrating an effect similar to the one using a multi Z-buffer while reducing the number of Z-buffers to be used.

• Proceedings of the IEEK Conference
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• 2000.06d
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• pp.54-57
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• 2000

In this paper, we propose a new interpolation method by using the motion between two moving image frames. In the proposed method, the movement is detected by using neighborhood pixels of target pixel in the past frame and the present frame. Then, H-shaped pseudomedian filter (below HPMED) is used for the still part of the image and Delta-shaped interpolation filter (below $\Delta$-shaped) for used in the moving part of the image. We detect the movement by comparing the differences between pixels in 4${\times}$5 window of the past frame and the present frame; the difference has a critical value. We simultaneously accomplish checking PSNR(peak signal noise ratio) and subjective assessment that is placed the focus on edge characteristic for assessment of result in computer simulation. The results show that the proposed adaptive method is better than the conventional methods.

• Journal of the Korean Society of Visualization
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• v.1 no.1
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• pp.75-81
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• 2003

A custom micro-PIV optics assembly has been used to measure the flow fold inside a T-junction of a microchannel. The micro-PIV system consists of microscope objectives of various magnifications, a dichroic cube, and an 8-bit CCD camera. Fluorescent particles of diameters 620 nm have been used with a Nd:YAG laser and color filters. A programmable syringe pump with Teflon tubings were used to inject particle-seeded distilled water into the channel at flow rates of 2.0, 4.0, 6.0 mL/hr. The micro-channels are fabricated with PDMS with a silicon mold, then O$_{2}$ -ion bonded onto a slide glass. Results show differences in flow characteristics and resolution according to fluid injection rates, and magnifications, respectively. The results include PIV data with vector-to-vector distances of 2 $\mu$m with 32 pixel-square interrogation windows at 50$\%$ overlap.

• Proceedings of the KSME Conference
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• 2002.08a
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• pp.423-426
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• 2002

A custom micro-PIV optics assembly has been used to measure the flow field inside a T-shaped microchannel. The micro-PIV system consists of microscope objectives of various magnifications, a dichroic cube, and an 8-bit CCD camera. Fluorescent particles of diameters 620nm have been used with a Nd:YAG laser and color filters. A programmable syringe pump with Teflon tubings were used to inject particle-seeded distilled water into the channel at flow rates of $420,\;40,\;60{\mu}L/hr$. The microchannels are fabricated with PDMS with a silicon mold, then $O_2-ion$ bonded onto a slide glass. Results show differences in flow characteristics and resolution according to fluid injection rates, and magnifications, respectively. The results show PIV results with vector-to-vector distances of $2{\mu}m$ with 32 pixel-square interrogation windows at $50{\%}$ overlap.

• Journal of the Korean Institute of Telematics and Electronics B
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• v.32B no.8
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• pp.1091-1098
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• 1995

This paper proposes an efficient noiseless encoding method of vector quantization(VQ) index using a dynamic index mapping. Using high interblock correlation, the proposed index mapper transforms an index into a new one with lower entropy. In order to achieve good performance with low computational complexity, we adopt 'the sum of differences in pixel values on the block boundaries' as the cost function for index mapping. Simulation results show that the proposed scheme reduces the average bitrate by 40 - 50 % in ordinary VQ system for image compression. In addition, it is shown that the proposed index mapping method can be also applied to mean-residual VQ system, which allows the reduction of bitrate for VQ index by 20 - 30 %(10 - 20 % reduction in total bitrate). Since the proposed scheme is one for noiseless encoding of VQ index, it provides the same quality of the reconstructed image as the conventional VQ system.

• Journal of information and communication convergence engineering
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• v.10 no.3
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• pp.300-306
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• 2012

An image attention model and its application to image quality assessment are discussed in this paper. The attention model is based on rarity quantification, which is related to self-information to attract the attention in an image. It is relatively simpler than the others but results in taking more consideration of global contrasts between a pixel and the whole image. The visual attention model is used to develop a local distortion predictor, named color visual differences predictor (CVDP), in color images in order to effectively detect luminance and color distortions.

• Journal of Korea Multimedia Society
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• v.24 no.12
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• pp.1614-1623
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• 2021

In this paper, the purpose is evaluation of the effect of using fractal feature in machine learning based pancreatic tumor classification. We used the data that Pancreas CT series 469 case including 1995 slice of benign and 1772 slice of malignant. Feature selection is implemented from 109 feature to 7 feature by Lasso regularization. In Fractal feature, fractal dimension is obtained by box-counting method, and hurst coefficient is calculated range data of pixel value in ROI. As a result, there were significant differences in both benign and malignancies tumor. Additionally, we compared the classification performance between model without fractal feature and model with fractal feature by using support vector machine. The train model with fractal feature showed statistically significant performance in comparison with train model without fractal feature.

• Proceedings of the KSRS Conference
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• 2005.10a
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• pp.542-545
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• 2005

Spaceborne radar interferometry has been widely used to estimate the topography and deformation of the Earth. It is difficult to obtain coherent interferometric SAR pairs especially over coastal areas mainly because of variation of surface conditions. We carried out the experiment using a cross-interferometric pair with a perpendicular baseline of about 1.4 km, a 30 minutes temporal separation and the height sensitivity of about 6 meters. The temporal decorrelation can be reduced by the cross interferometric technique with a 30 minutes temporal separation. Accurate coregistration was performed through resampling of ENVISAT ASAR data to equivalent pixel spacing to the ERS SAR data, because of the differences of the pulse repetition frequency and range sampling rate between the two sensors. Then we estimated range and azimuth offset to a sub-pixel accuracy using image intensity cross correlation. A larger window chip size than a general case was used because it was difficult to distinguish typical features. As range bin increased, the difference of Doppler centroid also increased. It resulted in lower coherence in far range than in near range. Coherences over wetland in near and far range were about 0.8 and 0.5, respectively. The coherence was improved by applying azimuth and range common band filtering, but coherence gap still existed. ERS-ENVISAT cross-interferogram usually lost information in urban area. However, high coherence over a city in this pair was shown, because of less man-made structures than other major cities. Accuracy of the DEM constructed by the ERS-ENVISAT 30-minute pair in a coastal area is to be evaluated.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.46 no.2
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• pp.78-84
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• 2009

In general video coding systems, motion estimation (ME) is regarded as a vital component in a video coder as it consumes a large amount of computation resources. Fractional pixel motion estimation can improve the video compression rate at the cost of higher computational complexity. It is based on the experimental results that the sum of absolute differences (SAD) shows parabolic shape and thus can be approximated by using interpolation technique. In this paper, we propose a fast fractional pixel search algorithm by combining SASR (Simplified Adaptive Search Range) and the CBCDS (Center Biased Cross-Diamond Search) pattern with the predicted motion vector. Compare with the fractional pel full search and the CBFPS, the proposed CBCDS algorithms can reduce fractional pel search points up to 81.4%, respectively with the PSNR lost about 0.05dB.