• Journal of Broadcast Engineering
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• v.4 no.1
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• pp.68-75
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• 1999

In this paper. we propose a digital watermarking method for still images in the discrete cosine transform (DCT) domain. The adaptive watermark insertion method in the high frequency region within a given image is employed to increase the invisibility of the inserted watermark in images, in which variable block-size method is used for selection of the high frequency region. Experimental results show that the proposed watermarking method is robust to several common image processing techniques. including joint photographic experts group (JPEG) compression, lowpass filtering, multiple watermarking, and croppIng.

• Electronics and Telecommunications Trends
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• v.38 no.2
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• pp.66-74
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• 2023

Holography is the most promising 3D imaging technology to faithfully record and reproduce light information. In addition, it is widely explored in metrology for applications such as microscopy and tomography because it can accurately measure 3D shapes. However, the data size of a digital hologram is very large, and the data characteristics are notably different from those of conventional 2D images. The Joint Photographic Experts Group (JPEG) is a group of experts from the International Organization for Standardization/International Electrotechnical Commission. This group develops and maintains standards for still image compression. In 2014, the JPEG released a new standard for 3D image compression called JPEG Pleno to represent light fields, point clouds, and holograms. Among them, JPEG Pleno Holography is the first international standard for hologram compression. We review recent advances in JPEG Pleno Holography standardization and discuss future directions of development.

• Explosives and Blasting
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• v.37 no.4
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• pp.1-9
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• 2019

In this study the applicability of a Digital Image Correlation (DIC) method was investigated by measuring the displacement and vibration of rock pillar due to underground mining blasting. When combined with a high speed photography technology, the DIC method provides an excellent photographic image processing ability that can be used to convert the evolving full-field surface properties of structures to 2D or 3D set of coordinate values. The measured coordinate sets are then used to calculate the displacement, strain, and velocity of the target structure. This technique is widely used in science and engineering, and continuously finds its new application areas. In this study, the DIC system and the conventional seismograph were compared for their ability to measure the displacement and vibration produced by blasting. In the field test both methods showed similar results. Thus, it is concluded that the DIC method is feasible to measure the ground displacements and vibrations from blasting.

• Journal of Korean Society for Geospatial Information Science
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• v.11 no.4 s.27
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• pp.3-11
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• 2003

Lately, digital photogrammetry based on the principles of photographic suey has been more and more applied to various high-tech industries and becomes one of more interesting focuses of study than ever. Thus, this study aims to develop a roadway information system by means of digital photogrammetry. Data acquired from digital photogrammetry were processed via Delphi, an object-oriented programming language to develop a computer aided program that allows us to build up the information on road horizontal alignment(BC, EC, R. IP), road vertical alignment and road facilities. And the developed program could maximize the visual effects better than traditional programs, because it used many image data.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2019.05a
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• pp.217-219
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• 2019

In response to the increased use of digital video device, more researches are actively made on the image processing technologies. Image processing is practically used on various applied fields such as medical photographic interpretation, and object recognition. The types of image noise include Gaussian Noise, Impulse Noise, and Salt and Pepper. Noise refers to the unnecessary information which damages the video and the noise is mainly removed by a filter. Typical noise removal methods are Median Filter and Average Filter. While Median Filter is effective for removing Salt and Pepper noise, the noise removal performance is relatively lower in the environment with high noise density. To address such issue, this study suggested an algorithm which utilizes neighboring pixels to remove noise.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.42 no.2
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• pp.171-178
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• 2009

The purpose of this study was the development of a digital water color measurement system using a CCD optical device. Photographs of the standard medium of Forel and Ule water color scales in the laboratory, and one of sea surface above a Secchi disc (Z=SD/2) immersed in seawater were taken. The colors of these pictures were estimated with the value of CIE $L^*a^*b^*$. Water color assessment was conducted with a digital photo-image. In the case of the Forel scale (No. 1-11), the $b^*$ value was so high that the water color number was large. In the Ule scale (No.11-21), the $a^*$ value became high, which is why the number on the water color scale was large. The color of these pictures showed that the $a^*$ value in the Forel scale and the $b^*$ value in the Ule scale increase with the increase of the F value. The $a^*$ value of seawater color was always lower than the one on the Forel and Ule water color scales. This indicates that the color of the scales differs from actual seawater color. It was concluded that water color number can more effectively be assessed by estimating the ${\Delta}Eab^*$ color difference between the water scales and actual seawater color.

• Journal of Korean Society for Geospatial Information Science
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• v.10 no.1 s.19
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• pp.91-100
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• 2002

Recently, many studies on the construction of management system for road facility have been accomplished, and in its process the digital map is used as the essential data for spatial database. But in case where the existing topographical map or completion map of construction data is not sufficient for Data Base construction, the compilation, modification or renewal of digital map should be conflicted with large obstacles. This study intended to extract the road facility information using the image data of various form such as aerial photographs, terrestrial photographs and so on. The terrestrial photographic images are taken by hand-held camera, digital camera and video camera which are widely used and of low price in general. This study used the single frame images only for the raw image data, and the extracted spatial and attribute data from the images are used for modifying and updating the database. In addition, the creating possibility of the digital map in the relative scale using the spatial data extracted from the single images was tried.

• Journal of the Korean Association of Geographic Information Studies
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• v.7 no.4
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• pp.77-87
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• 2004

It is important for hydrographers to extract the accurate cross section of a river for the hydrographical analysis of the topography. Aerial photographs were used to extract the cross section of a river for the advantages of the accuracy and economical efficiency in this study, while the direct measurement has been used in existing studies. An ortho-rectified photo map using imageries taken by the PKNU 2 (High-resolution, multi-spectral, aerial photographic system developed by our laboratory) was generated using the surveyed data and a digital map. The cross section of a river that was obtained from the ortho-rectified by the surveyed Kinematic data of GPS was compared with the result using ImageStation stereo-plotter of corp. Z/I Imaging. As a result of this study, the RMSE in the ortho-rect process using the surveyed GPS data was lowered as from 5.5788 pixels (about 2m) to 2.84 (about 1m) in comparison with it in the process using a digital map. The surveyed kinematic GPS in extraction of the cross section of a river was excellent as 6.6cm of the planimetric and precision in the confidence level of 95%. The correlation coefficient between the result from the using stereo-plotter and the extraction of cross section of a river using aerial photos was 0.8 hydrographical acquisition of it using PKNU 2 imagery will be possible.

• Proceedings of the KIEE Conference
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• 1993.07a
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• pp.504-506
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• 1993

The Joint Photographic Experts Group (JPEG) standard was proposed by the International Standardization Organization (ISO/SC 29/WG 10) and the CCITT SG VIII as an international standard for digital continuous-tone still image compression. The JPEG standard has been widely accepted in electronic imaging, computer graphics, and multi-media applications, however, due to the lossy character of the JPEG compression its application in the field of medical imaging has been limited. In this paper, the JPEG standard was applied to a series of head sections of magnetic resonance (MR) images (256 gray levels, $256{\times}256$ size) and its performance was investigated. For this purpose, DCT-based sequential mode of the JPEG standard was implemented using the CL550 compression chip and progressive and lossless coding was implemented by software without additional hardware. From the experiment, it appears that the compression ratio of about 10 to 20 was obtained for the MR images without noticeable distortion. It is also noted that the error signal between the reconstructed image by the JPEG and the original image was nearly random noise without causing any special-pattern-related artifact. Although the coding efficiency of the progressive and hierarchical coding is identical to that of the sequential coding in compression ratio and SNR, it has useful features In fast search of patient Image from huge image data base and in remote diagnosis through slow public communication channel.

• Transactions of the Korean Society of Mechanical Engineers
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• v.12 no.5
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• pp.1121-1129
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• 1988

An economic and efficient system for measuring drop sizes was developed. Pattern recognition technique was used with conventional oil-bath sampling and photographic method. The system was designed to measure and count relatively large number of drops in a very short time, and also to filter out abnormal images such as drops in contact or overlap as well as odd-shaped foreign materials. In this measuring system, most important error originates from the process of converting the original image to the binary image. If the photograph contains a large number of spray drops, the relative size of the pixel to the drops is not infinitesimally small; thus the proper choice of threshold level to convert the original image to the binary image becomes very important. In present case, most of the images lay in one of the two separate bands of brightness level and the arithmetic mean of the most popular brightness levels from each band was chosen as the threshold level. Present image processing system reduces the subjective error by the observers in counting and measuring drops and turns out to be substantially effective. The processing time can be further reduced by improving the hardware system concerned with the digital image coding.