• Journal of Institute of Control, Robotics and Systems
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• v.22 no.9
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• pp.710-715
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• 2016

Due to its simplicity and high reliability, the box-counting(BC) method is one of the most frequently used techniques to estimate the fractal dimensions of a binary image with a self-similarity property. The fractal calculation requires data sampling that determines the size of boxes to be sampled from the given image and directly affects the accuracy of the fractal dimension estimation. There are three non-overlapping regular grid methods: geometric-step method, arithmetic-step method and divisor-step method. These methods have some drawbacks when the image size M becomes large. This paper presents a BC algorithm for enhancing the accuracy of the fractal dimension estimation based on a new sampling method. Instead of using the geometric-step method, the new sampling method, called the coverage ratio-step method, selects the number of steps according to the coverage ratio. A set of experiments using well-known fractal images showed that the proposed method outperforms the existing BC method and the triangular BC method.

• Journal of Korean Academy of Oral and Maxillofacial Radiology
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• v.20 no.2
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• pp.219-225
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• 1990

Panoramic radiography is convenient in clinic and visualizes those areas which other technique do not give. But the technique has limitation of image distortion which results from the relationship of the ramus to the focal trough and from the direction of the central ray. This study is, using 7 dry skulls, to determine the effect of rotation of patient's head on reducing those distortion and determine the magnification ratio of images of mandibular condyle in rotated patient head position. The obtained results were as follows: 1. Generally, in panoramic radiography the anterolateral portion of the mandibular condyle was best to be visualized. 2. There are no significant difference between the image readability of anteromedial portion and that of anterocentral portion of the mandibular condyle. 3. Anterolateral portion of the mandibular condyle was better visualized in rotated head position by 20 degree or horizontal condylar inclination than in conventional position or in rotated head position by 10 degree. 4. The magnification ratio of the anteroposterior diameter in the image of mandibular condyle was least in the rotated head position by horizontal inclination of the mandibular condyle and was largest by 20 degree.

• Journal of IKEEE
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• v.24 no.4
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• pp.942-949
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• 2020

In this paper, we propose an improved algorithmic ADC for CMOS Image Sensor that is suitable for a column-parallel readout circuit. The algorithm of the conventional algorithmic ADC is modified so that it can operate as a single amplifier while being independent of the capacitor ratio and insensitive to the gain of the op-amp, and it has a high conversion efficiency by using an adaptive biasing amplifier. The proposed ADC is designed with 0.18-um Magnachip CMOS process, Spectre simulation shows that the power consumption per conversion speed is reduced by 37% compared with the conventional algorithmic ADC.

• Journal of Information Processing Systems
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• v.19 no.4
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• pp.465-473
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• 2023

An image enhancement algorithm and image defogging method are studied in this paper. The formation of fog and the characteristics of fog image are analyzed, and the fog image is preprocessed by histogram equalization method; then the additive white noise is removed by foggy image attenuation model, the atmospheric scattering physical model is constructed, the image detail characteristics are enhanced by image enhancement method, and the visual effect of defogging image is enhanced by guided filtering method. The proposed method has a good defogging effect on the image. When the number of training iterations is 3,000, the peak signal-to-noise ratio of the proposed method is 43.29 dB and the image structure similarity is 0.9616, indicating excellent image defogging effect.

• Science of Emotion and Sensibility
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• v.11 no.3
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• pp.325-338
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• 2008

This study aims to characterize the effect of different combinations of chromatic-achromatic colors and area-ratio of stripe necktie, and gender on the image of male wearer. The experimental materials developed for this study are a set of stimuli and response scales. The stimuli consist of 84 color pictures manipulated with every combination of 12 different colors and 7 different area-ratio. The 7-point scale designed for visual evaluation of image formation included 26 bipolar adjectives. The subjects were 2016 undergraduate students in Gyeongnam, Seoul, Busan, and Daegu areas. The results of this study were as follows.; The analyses of images of male wearer in terms of combinations of chromatic-achromatic colors and area-ratio of oblique stripe necktie reveal that the concerned factors are of five characteristic dimensions of youth-activity, ability, attractiveness, appeal, and warmness. In addition, it has been found that individual images of male wearer are affected by observer's gender as well as combinations of chromatic-achromatic colors and area-ratio of stripe neckties and that those images vary with every combination of each factor. The study results are highly expected to be used as useful sources in developing necktie designs.

• Journal of Korea Multimedia Society
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• v.18 no.8
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• pp.901-908
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• 2015

Methods of detecting, describing, matching image features, like corners and blobs, have been actively studied as a fundamental step for image processing and computer vision applications. As one of feature description/matching methods, LLAH(Locally Likely Arrangement Hashing) describes image features based on the geometric relationship between their neighbors, and thus is suitable for scenes with poor texture. This paper presents a modified LLAH algorithm, which includes the image features themselves for robustly describing the geometric relationship unlike the original LLAH, and employes a voting-based feature matching scheme that makes feature description much simpler. Then, this paper quantitatively analyzes its performance with synthetic images in the presence of Gaussian noise.

• Journal of the Korean Institute of Telematics and Electronics B
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• v.33B no.3
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• pp.96-108
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• 1996

In this paper, we propose an object-oriented coding method in low bit-rate channels using block-based motion vectors and residual image compensation. First, we use a 2-stage algorithm for estimating motion parameters. In the first stage, coarse motion parameters are estimated by fitting block-based motion vectors and in the second stage, the estimated motion parametes are refined by the gradient method using an image reconstructed by motion vectors detected in the first stage. Local error of a 6-parameter model is compensted by blockwise motion parameter correction using residual image. Finally, model failure (MF) region is reconstructed by a fractal mapping method. Computer simulation resutls show that the proposed method gives better performance than the conventional ones in terms of th epeak signal to noise ratio (PSNR) and compression ratio (CR).

• International Journal of Precision Engineering and Manufacturing
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• v.8 no.1
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• pp.38-45
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• 2007

We propose a preprocessing method for removing floating particles from underwater images based on an analysis of the image features. We compared baseline JPEG and wavelet codec methods to determine the method best suited for underwater images. The proposed preprocessing method enhanced the compression ratio and resolution, and provided an efficient means of compressing the images. The wavelet codec method yielded better compression ratios and image resolutions. The results suggest that the wavelet codec method linked with the proposed preprocess method provides an efficient codec processor and transmission system for underwater images that are used for searches and transmitted via ultrasonic communications.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.21 no.12
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• pp.3033-3045
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• 1996

In this paper, we propse an object-oriented coding method in low bit-rate channels using pyramid structure and residual image compensation. In the motion estimation step, global motion is estimated using a set of multiresolution images constructed in a pyramid structure. We split an input image into two regions based on the gradient value. Regions with larte motions obtain observation points at low resolution level to guarantee robustness to noise and to satisfy a motion constraint equation whereas regions with local motions such as eye, and lips get observation points at the original resolution level. Local motion variations and intesity variations of an image reconstructed by the golbal motion are compensated additionally by using the previous residual image component. Finally, the model failure (MF) region is compensated by the pyramid mapping of the previous displaced frame difference (DFD). Computer simulation results show that the proposed method gives better performance that the convnetional one in terms of the peak signal to noise ratio (PSNR), compression ratio (CR), and computational complexity.

• KIEE International Transactions on Electrophysics and Applications
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• v.4C no.6
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• pp.272-275
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• 2004

A balanced single side-band (SSB) mixer employing a sub-harmonic configuration is designed for up and down conversions in K-band. The designed mixer uses anti-parallel diode (APD) pairs to effectively eliminate even harmonics of the local oscillator (LO) spurious signal. To reduce the odd harmonics of LO at the RF port, we employ a balanced configuration for LO. The fabricated chip shows 12$\pm$2dB of conversion loss and image-rejection ratio of about 20dB for down conversion at RF frequencies of 24-27.5GHz. As an up-conversion mode, the designed chip shows 12dB of conversion loss and image-rejection ratio of 20 ～ 25 dB at RF frequencies of 25 to 27GHz. The odd harmonics of the LO are measured below -37dBc.