• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.32 no.3
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• pp.217-223
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• 2014

With precise sensor position, attitude element, and imaging resolution, a simulated geospatial image can be generated. In this study, a satellite image is simulated using SPOT ortho-image and global elevation data, and the geometric similarity between original and simulated images is analyzed. Using a SPOT panchromatic image and high-density elevation data from a 1/5K digital topographic map data an ortho-image with 10-meter resolution was produced. The simulated image was then generated by exterior orientation parameters and global elevation data (SRTM1, GDEM2). Experimental results showed that (1) the agreement of the image simulation between pixel location from the SRTM1/GDEM2 and high-resolution elevation data is above 99% within one pixel; (2) SRTM1 is closer than GDEM2 to high-resolution elevation data; (3) the location of error occurrence is caused by the elevation difference of topographical objects between high-density elevation data generated from the Digital Terrain Model (DTM) and Digital Surface Model (DSM)-based global elevation data. Error occurrences were typically found at river boundaries, in urban areas, and in forests. In conclusion, this study showed that global elevation data are of practical use in generating simulated images with 10-meter resolution.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2005.06a
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• pp.749-752
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• 2005

In the industry, three-dimensional coloring has been needed for realistic prototype from rapid prototyping. Z-corporation developed a 3D printer which provides three-dimensional colored prototype. However, the existing process cannot be adopted to models from other rapid prototyping process. In addition, time and cost for manufacturing colored prototype still remain to be improved. In this study, a new coloring process using ink-jet head is proposed for color printing on three-dimensional prototype surface. Process parameters such as the angle and the distance between ink-jet nozzle and the three-dimensional surface should be investigated from experiments. The correction matrix according to sloped angle to minimize the distortion of 2D image was proposed by analysis of printing error. Therefore, approximated method for angle and discrete length according to the radius of curvature for printing on the curved surface was proposed. By printing image on the doubly curved surface, the method was verified. As a practical example, helmet was chosen for printing images on the curved surface. The character images were applied with approximated method for angle and discrete length and was printed on the helmet surface.

• Journal of Biosystems Engineering
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• v.17 no.4
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• pp.354-362
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• 1992

This study was intended to examine feasibility of sizing and color grading of Fuji apple with black/white image processing system, to develop a device with which the whole surface of an apple could be captured by one camera, and to develop an algorithm for a high speed sorting. The results are summarized as follows : 1. The black/white image processing system used in this study showed a maximum error of 1.3% in area measurement with a reference figure while the focusing point of camera and location of the reference figure were changed within a certain range. 2. As the result of evaluating four automatic image segmentation algorithms with apple images, Histogram Clustering Method was the best in terms of computation time and accuracy. 3. The fast algorithm for analyzing size and coloration of apple was developed. 4. The whole surface of an apple could be captured in an image frame with two mirrors installed on the both sides of the sample. The total area of the image representing the whole surface showed a correlation of 0.995 with the weight of apple. 5. The gray level when a particular band pass filter was mounted on the camera showed high correlation with 'L' and 'a' values of Hunt color scale and could represent the coloration of apple.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2006.10a
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• pp.71-78
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• 2006

The image of an object obtained by the radar is not corresponding to its true shape, because the image of an object observed by the radar is receiving an influence such as multiple-reflections and expanded in bearing because of the beam width of a radar. In addition, a radio wave does not hit the entire surface of an object. Therefore, the image of the front side of a ship facing a radar antenna corresponds to its true shape. In this paper, a method to estimate a ship's shape by means of the integration of the front parts of images obtained from radars is proposed. In addition, a matter, which is observation error of each radar, in using multi-radars, and the process included in the proposed method for solving the matter, are described. As a result of the experiment, the accuracy of about 3 degrees in ship's heading and about 14 meters in length and about 9 meters in beam was obtained.

• Current Optics and Photonics
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• v.7 no.4
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• pp.387-397
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• 2023

Tooth surface shape error is an important parameter in gear accuracy evaluation. When tooth surface shape error is measured by laser interferometry, the gear interferogram is highly distorted and the gray level distribution is not uniform. Therefore, it is important for gear interferometry to extract the foreground region from the gear interference fringe image directly and accurately. This paper presents an approach for foreground extraction in gear interference images by leveraging the sinusoidal variation characteristics shown by the interference fringes. A gray level mask with an adaptive threshold is established to capture the relevant features, while a local variance evaluation function is employed to analyze the fluctuation state of the interference image and derive a repair mask. By combining these masks, the foreground region is directly extracted. Comparative evaluations using qualitative and quantitative assessment methods are performed to compare the proposed algorithm with both reference results and traditional approaches. The experimental findings reveal a remarkable degree of matching between the algorithm and the reference results. As a result, this method shows great potential for widespread application in the foreground extraction of gear interference images.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2003.07a
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• pp.191-194
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• 2003

Through using aspheric lens can result in advantages such as an improved optical transfer function, a reduced distortion path or the realization of special image field curvatures. Using the diamond turning method for generating aspherics, the company claim to be able to generate surfaces with a form error of less than $0.33\;{\mu}\;m$ and a surface roughness of less than $0.025\;{\mu}\;m$. In this paper, we are manufacturing thermal image aspheric lens. Thermal image system is electro-optical imaging device which can make visible the difference of infrared energy naturally emitted by objected. In the result of aspherical surface, the form accuracy of about $0.24\;{\mu}\;m$ P-V was obtained and the surface roughness Ra $0.004\;{\mu}\;m$. Also, a brief review of Ultra-precision system Korea photonics technology institute(KOPTI) is present in this paper.

• The Journal of the Korea Contents Association
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• v.11 no.3
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• pp.18-25
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• 2011

In a manufacturing process of metal coins, surface defects of coins are manually detected. This paper describes an new method for detecting surface defects of metal coins on a moving conveyor belt using image processing. This method consists of multiple procedures: segmentation of a coin from the background, alignment of the coin to the model, projection of the aligned coin to the best eigen image space, and detection of defects by comparison of the projection error with an adaptive threshold. In these procedures, the alignement and the projection are newly developed in this paper for the detection of coin surface defects. For alignment, we use the histogram of the segmented coin, which converts two-dimensional image alignment to one-dimensional alignment. The projection reduces the intensity variation of the coin image caused by illumination and coin rotation change. For projection, we build multiple eigen image spaces and choose the best eigen space using estimated coin direction. Since each eigen space consists of a small number of eigen image vectors, we can implement the projection in real- time.

• The Bulletin of The Korean Astronomical Society
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• v.44 no.1
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• pp.52.1-52.1
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• 2019

The Helioseismic and Magnetic Imager (HMI) is the instrument of Solar Dynamics Observatory (SDO) to study the magnetic field and oscillation at the solar surface. The HMI image is not enough to analyze very small magnetic features on solar surface since it has a spatial resolution of one arcsec. Super resolution is a technique that enhances the resolution of a low resolution image. In this study, we use a method for enhancing the solar image resolution using a Deep-learning model which generates a high resolution HMI image from a low resolution HMI image (4 by 4 binning). Deep learning networks try to find the hidden equation between low resolution image and high resolution image from given input and the corresponding output image. In this study, we trained a model based on a very deep residual channel attention networks (RCAN) with HMI images in 2014 and test it with HMI images in 2015. We find that the model achieves high quality results in view of both visual and measures: 31.40 peak signal-to-noise ratio(PSNR), Correlation Coefficient (0.96), Root mean square error (RMSE) is 0.004. This result is much better than the conventional bi-cubic interpolation. We will apply this model to full-resolution SDO/HMI and GST magnetograms.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.19 no.10
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• pp.1880-1893
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• 1994

In this paper, we propose a new shape from shading algorithm which reconstructs object shapes from a single image. In the proposed intative algorithm, given 3D surfaces are approximated by orthogonal polynomials and the relationships between the given surface and its derivatives are constructed ad matrix forms in terms of polynomial coefficients, Also the relative depth and its derivatives are obtained by updating them iteratively. Performance of the propose shape from shading algorithm is evaluated in terms of brightness error, orientation error, and height error, and the performance comparison of the proposed and conventional algorithms is shown.

• Journal of Environmental Science International
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• v.23 no.4
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• pp.571-584
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• 2014

The present study aims to apply a surface image velocimetry(SIV) system to video images captured with CCTV and estimate the flood discharge. The CCTV was installed at the Hancheon Bridge of the Han Cheon in Jeju Island for disaster surveillance, and seven flood events occurred in 2012 were used. During the image analyses, input parameters, interrogation areas and searching areas were determined with proper calibration procedures. To check for accuracy and applicability of SIV, the velocities and flood discharges estimated by SIV were compared with the measured ones by an electromagnetic surface velocimeter, Kalisto. The comparison results showed fairly good agreements. The RMSE(Root Mean Square Error) values between two instruments showed a range of 4.13 and 14.2, and the determination coefficients reached 0.75 through 0.85. It means that the SIV could be used as a good alternative method for other traditional velocity measuring instruments in measuring flood discharges.