• Journal of Ocean Engineering and Technology
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• v.34 no.6
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• pp.442-453
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• 2020

Underwater color images suffer from low visibility and color cast effects caused by light attenuation by water and floating particles. This study applied single image enhancement techniques to enhance the quality of underwater images and compared their performance with real underwater images taken in Korean waters. Dark channel prior (DCP), gradient transform, image fusion, and generative adversarial networks (GAN), such as cycleGAN and underwater GAN (UGAN), were considered for single image enhancement. Their performance was evaluated in terms of underwater image quality measure, underwater color image quality evaluation, gray-world assumption, and blur metric. The DCP saturated the underwater images to a specific greenish or bluish color tone and reduced the brightness of the background signal. The gradient transform method with two transmission maps were sensitive to the light source and highlighted the region exposed to light. Although image fusion enabled reasonable color correction, the object details were lost due to the last fusion step. CycleGAN corrected overall color tone relatively well but generated artifacts in the background. UGAN showed good visual quality and obtained the highest scores against all figures of merit (FOMs) by compensating for the colors and visibility compared to the other single enhancement methods.

• 제어로봇시스템학회:학술대회논문집
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• 1988.10b
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• pp.822-825
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• 1988

In this paper, we present a system which enables a real-time measurement of the number and also the body length of the fry (baby fish) using a line image sensor. Here, we consider a situation that fry are transported from a pond to another, pond through a pipe. At one position of the pipe a transparent rectanglar channel is mounted. The images of the fry, which run through this rectanglar channel, are detected by a line image sensor. The image signals are digitized to binary ones and the contour of the fry are detected. After that, a real-time image analysis is executed with a digital signal processor. Labeling program analyses the connection of every pixel. The results are transfered to a personal computer and displayed on the online monitor graphically.

• Proceedings of the KSRS Conference
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• 2007.10a
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• pp.530-532
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• 2007

Multi-Spectral Camera(MSC) is a main payload on the KOMPSAT-2 satellite to perform the earth remote sensing. The MSC instrument has one(1) channel for panchromatic imaging and four(4) channel for multi-spectral imaging covering the spectral range from 450nm to 900nm using TDI CCD Focal Plane Array (FPA). The compression method on KOMPSAT-2 MSC was selected and used to match EOS input rate and PDTS output data rate on MSC image data chain. At once the MSC performance was carefully handled to minimize any degradation so that it was analyzed and restored in KGS(KOMPSAT Ground Station) during LEOP and Cal./Val.(Calibration and Validation) phase. In this paper, on-orbit image data chain in MSC and image data processing on KGS including general MSC description is briefly described. The influences on image performance between on-board compression algorithms and between performance restoration methods in ground station are analyzed and discussed.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.22 no.11
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• pp.2543-2551
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• 1997

This paper proposes a compression technique of image data, a variable length PN code and channel models which are required in CDMA communication system. It also analyzes their performances. Original images is compressed by 2-D DCT and its coefficients are quantized by optimal quantizer at compression rate 0.84bit/pel. Channel model 1 and 2 which are composed of 5 and 4 channels respectively are employed to be used in CDMA. Such a situation forces us to empoly variable length PN code, such as Chebyshev map for spread spectrum system. When average PN code length of model 1 and 2 is 44.4 and 26.7 chips respectively, the received image through these models under Gaussian noise with variance 1.75 is visually of the same quality as the transmitting image. Thus, the model 2 appears to be better in channel efficiency, comparing with channel model 1 and channel model which uses fixed length PN code.

• Journal of the Optical Society of Korea
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• v.14 no.1
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• pp.42-48
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• 2010

We used video-rate Confocal Laser Scanning Microscopy (CLSM) to observe the motion of blood cells in a micro-channel. Video-rate CLSM allowed us to acquire images at the rate of 30 frames per second. The acquired images were used to perform Particle Image Velocimetry (PIV), thus providing the velocity profile of the blood in a micro-channel. While previous confocal microscopy-assisted PIV required exogenous micro/nano particles as the tracing particles, we employed blood cells as tracing particles for the CLSM in the reflection mode, which uses light back-scattered from the sample. The blood flow at various depths of the micro-channel was observed by adjusting the image plane of the microscope. The velocity profile at different depths of the channel was measured. The confocal micro-PIV technique used in the study was able to measure blood velocity up to a few hundreds ${\mu}m/sec$, equivalent to the blood velocity in the capillaries of a live animal. It is expected that the technique presented can be applied for in vivo blood flow measurement in the capillaries of live animals.

• Proceedings of the KSME Conference
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• 2001.06b
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• pp.53-58
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• 2001

In this paper, a low price ultrasound image processing system is developed using DSP and PC. Ultrasound for image is generated by the 32-channel transducer. Ultrasound image is captured by DSP instead of the private image grabber board. Display of image and image processing algorithms are performed by PC. The image processing algorithms based on GUI are realized by software. So users without knowledge of image processing can perform the image enhancement more easily.

• Journal of information and communication convergence engineering
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• v.8 no.2
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• pp.163-167
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• 2010

In underwater acoustic communication, acoustic signals from transducers or hydrophones are used. And the underwater acoustic communication channels are very complicated, because of vertical distribution of acoustic velocity according depths, and reflections from boundaries like as surface or bottom. For the implementation of the underwater acoustic communication channel, the image method or ray tracing method have been used. In this paper, we introduce a new approach for implementation of underwater acoustic communication channel using the simulation of the Transmission Line Matrix Modeling and cross-correlations from the input and output signals.

• Proceedings of the IEEK Conference
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• 2000.09a
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• pp.399-402
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• 2000

In this paper, we present a regularized mixed norm multichannel image restoration algorithm. The problem of multichannel restoration using both within- and between- channel deterministic information is considered. For each channel a functional which combines the least mean squares (LMS), the least mean fourth(LMF), and a smoothing functional is proposed, We introduce a mixed norm parameter that controls the relative contribution between the LMS and the LMF, and a regularization parameter that defines the degree of smoothness of the solution, both updated at each iteration according to the noise characteristics of each channel. The novelty of the proposed algorithm is that no knowledge of the noise distribution for each channel is required, and the parameters mentioned above are adjusted based on the partially restored image.

• Journal of Ocean Engineering and Technology
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• v.25 no.4
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• pp.23-27
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• 2011

This experimental study was performed to find rpms of the impeller and the surface flow accelerator to make a uniform velocity vertical distribution in the circular water channel. PIV technique was employed to measure the water velocity profiles into the water depth from the free surface. The number of instantaneous velocity profiles was decomposed into mean and turbulence velocity components, and the distribution of velocity fluctuation and turbulence intensity were computed for each experimental condition. From these results, the velocity uniformity was quantitatively determined to present the flow quality in the measuring section of the circular water channel. It has been shown that the proper operation of the surface flow accelerator would make the uniform velocity profiles and reduce the velocity fluctuation near the free surface.

• 한국정보통신설비학회:학술대회논문집
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• 2007.08a
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• pp.89-91
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• 2007

Multimedia service based on interactivity, personalization, multiple channels and community distinguishes IPTV from incumbent TV. But data encoding/decoding time and image frame processing should be considered in digital TV versus analog device. Especially channel zapping time is one of the most important parameters for the service quality of IPTV. This paper proposes the mechanism for decreasing the channel zapping time with multiple decoder and image frame processing. We also implemented the multi-group video community service system using IP multicasting function supporting interactive learning service.