• Journal of Broadcast Engineering
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• v.16 no.2
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• pp.247-257
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• 2011

In this paper, we propose a scene adaptive method to obtain two LDR images with proper shutter speeds which capture the irradiance of scene effectively. The proposed method adaptively selects two shutter speeds across the video frame even when the illumination varies continuously. For the performance evaluation, we compute the PNSR to the ground truth which is obtained by the state-of-the-art HDR imaging method. It shows that the proposed method is able to select approximately optimal shutter speeds while avoiding the exhaustive search of every possible pair of shutter speeds.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.13 no.10
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• pp.4676-4685
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• 2012

We investigated to compare the effects of a low intensity eccentric exercise and dynamic stretching on symptoms of delayed onset muscle soreness (DOMS). The eighteen women who had not participated in a regular exercise programme for the lower extremities in the previous five months were randomly assigned to one of three experimental groups: control group, a low intensity eccentric exercise group and dynamic stretching group. We measured the joint range of motion (ROM), maximal voluntary isometric exercise (MVIC), muscle soreness rating scale and ultrasound image measurement before eccentric exercise inducing DOMS, and 24, 48, and 72 hours after an eccentric exercise inducing DOMS. The exercise programme in a low intensity eccentric exercise group and dynamic stretching group were respectively performed 3 times a week for 4 weeks before eccentric exercise inducing DOMS. There was significantly different between the groups in muscle soreness rating scale and MVIC (p<.05). However, there was not significantly different between groups in ultrasound image measurement and ROM (p<.05). These results suggest that a low intensity eccentric exercise group and dynamic stretching group effectively reduced muscle soreness rating scale out of the symptoms of DOMS. A low intensity eccentric exercise group may be an effective improvement than dynamic stretching group in muscle soreness rating scale.

• Journal of the Ergonomics Society of Korea
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• v.17 no.2
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• pp.11-23
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• 1998

Dynamic motion difference between normal subjects and low-back pain (LBP) patients has been investigated in terms of kinematic variables such as range of motion, velocity and acceleration of the back and hip. Ten healthy subjects and ten LBP patients were recruited in this study. Electro-goniometer such as Lumbar Motion Monitor and Hip Monitor have been used for quantitative measurement of the trunk motion during repetitive flexion and extension for ten seconds. Results indicated that the velocity and acceleration of the back and hip were important parameters to quantitatively identify LBP patients. The consistency of cyclic trunk motion and the relationship between the back and hip were measured in terms of Variance Ratio and Phase Angle in order to accurately assess the motion characteristics of LBP patients. In particular, the hip motion has been proven to be a very important factor in describing the kinematics of damaged lower back. The functional evaluation technique suggested in this study will be a tool to assist physicians for an accurate diagnosis and timely rehabilitation along with current image diagnosis techniques.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.15 no.7
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• pp.4475-4481
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• 2014

A histogram equalization method have been used traditionally for the image enhancement of low quality images. This uses the transformation function, which is a cumulative density function of an input image, and it has mathematically maximum entropy. This method, however, may yield whitening artifacts. This paper proposes the weighted histogram equalization method based on histogram equalization. It has Weber-Fechner's law for a human's vision characteristics, and a dynamic range modification to solve the problem of some methods, which yield a transformation function, regardless of the input image. Finally, the proposed transformation function was calculated using the weighted average of Weber-Fechner and the histogram equalization transformation functions in a modified dynamic range. The simulation results showed that the proposed algorithm effectively enhances the contrast in terms of the subjective quality. In addition, the proposed method has similar or higher entropy than the other conventional approaches.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.5
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• pp.9-16
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• 2018

Images with lower illumination from the light source or with dark regions due to shadows, etc., can improve subjective image quality by using retinex-based image enhancement schemes. The retinex theory is a method that recognizes the relative lightness of a scene, rather than recognizing the brightness of the scene. The way the human visual system recognizes a scene in a specific position can be in one of several methods: single-scale retinex, multi-scale retinex, and multi-scale retinex with color restoration (MSRCR). The proposed method is based on the MSRCR method, which includes a color restoration step, which consists of three phases. In the first phase, the existing MSRCR method is applied. In the second phase, the dynamic range of the MSRCR output is adjusted according to its histogram. In the last phase, the proposed method transforms the retinex output value into the display dynamic range using a logarithm transformation function considering human visual system characteristics. Experimental results show that the proposed algorithm effectively increases the subjective image quality, not only in dark images but also in images including both bright and dark areas. Especially in a low lightness image, the proposed algorithm showed higher performance improvement than the conventional approaches.

• Journal of radiological science and technology
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• v.32 no.3
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• pp.277-283
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• 2009

It is important to get clinical ultrasonic images of good quality for accurate diagnosis. In this study, it observed the change of ultrasonic images against setting frequency, dynamic range(DR) and type of probes on ultrasonic scanner. In the experiment it evaluated image of LCS (Low Contrast Sensitivity) targets(-15, -6, -3, +3, +6, +15 dB) of a standard ultrasonic test phantoms(539,551, ATS, USA) similar to solid and cystic lesions. Its imaged from convex (C3-7IM) and linear probe (L5-12IM) on SA-9900 (Medison Ltd, Korea) scanner. The images obtained altering the setting parameters which are frequency(gen, pen, res, harmonic) mode and DR($40{\sim}100\;dB$). The quality of images evaluated compare with the nominal LCS value of target and measured LCS value. The results show that there was no significant changing of quality images altering DR 40, 60, 80, 100 dB against frequency in Convex probe but the image being the highest in LCS target at DR 60 dB, harmonic of frequency mode in the -15 dB target close to cystic lesion. In Linear probe, DR 40 dB, harmonic mode at -15 dB LCS target close to nominal value. It discussed necessity of evaluation about ROC(Receiver Operating Characteristic) from the psychological viewpoint and limit of evaluation from quantified images.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.38C no.10
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• pp.881-886
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• 2013

Even though a multi-view camera system is able to capture multiple images at different viewpoints, the color distributions of captured multi-view images can be inconsistent. This problem decreases the quality of multi-view images and the performance of post-image processes. In this paper, we propose an improved polynomial model for effectively correcting the color inconsistency problem. This algorithm is fully automatic without any pre-process and considers occlusion regions of the multi-view image. We use the 5th order polynomial model to define a relative mapping curve between reference and source views. Sometimes the estimated curve is seriously distorted if the dynamic range of extracted correspondences is quite low. Therefore we additionally estimate the first order polynomial model for the bottom and top regions of the dynamic range. Afterwards, colors of the source view are modified via these models. The proposed algorithm shows the good subjective results and has better objective quality than the conventional color correction algorithms.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.10 no.2
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• pp.837-856
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• 2016

Underwater image enhancement has received considerable attention in last decades, due to the nature of poor visibility and low contrast of underwater images. In this paper, we propose a new automatic underwater image enhancement algorithm, which combines nonsubsampled contourlet transform (NSCT) domain enhancement techniques with the mechanism of the human visual system (HVS). We apply the multiscale retinex algorithm based on the HVS into NSCT domain in order to eliminate the non-uniform illumination, and adopt the threshold denoising technique to suppress underwater noise. Our proposed algorithm incorporates the luminance masking and contrast masking characteristics of the HVS into NSCT domain to yield the new HVS-based NSCT. Moreover, we define two nonlinear mapping functions. The first one is used to manipulate the HVS-based NSCT contrast coefficients to enhance the edges. The second one is a gain function which modifies the lowpass subband coefficients to adjust the global dynamic range. As a result, our algorithm can achieve contrast enhancement, image denoising and edge sharpening automatically and simultaneously. Experimental results illustrate that our proposed algorithm has better enhancement performance than state-of-the-art algorithms both in subjective evaluation and quantitative assessment. In addition, our algorithm can automatically achieve underwater image enhancement without any parameter tuning.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.23 no.5
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• pp.109-114
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• 2023

In this paper, a 2-channel Image-Reject receiver using a 65-nm CMOS process is presented for Ka-band compact radars. The designed receiver consists of Low-Noise Amplifier (LNA), IQ mixer, and Analog Baseband (ABB). ABB includes a complex filter in order to suppress unwanted images, and the variable gain amplifiers (VGAs) in RF block and ABB have gain tuning range from 4.5-56 dB for wide dynamic range. The gain of the receiver is controlled by on-chip SPI controllers. The receiver has noise figure of <15 dB, OP1dB of >4 dBm, image rejection ratio of >30 dB, and channel isolation of >45 dB at the voltage gain of 36 dB, in the Ka-band target frequency. The receiver consumes 420 mA at 1.2 V supply with die area of 4000×1600 ㎛.

• Journal of Astronomy and Space Sciences
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• v.28 no.4
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• pp.273-284
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• 2011

A method of stellar source selection for validating the quality of image is investigated for a low Earth orbit optical remote sensing satellite. Image performance of the optical payload needs to be validated after its launch into orbit. The stellar sources are ideal source points that can be used to validate the quality of optical images. For the image validation, stellar sources should be the brightest as possible in the charge-coupled device dynamic range. The time delayed and integration technique, which is used to observe the ground, is also performed to observe the selected stars. The relations between the incident radiance at aperture and V magnitude of a star are established using Gunn & Stryker's star catalogue of spectrum. Applying this result, an appropriate image performance index is determined, and suitable stars and areas of the sky scene are selected for the optical payload on a remote sensing satellite to observe. The result of this research can be utilized to validate the quality of optical payload of a satellite in orbit.