• Current Optics and Photonics
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• v.5 no.4
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• pp.402-408
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• 2021

An off-axis system refers to an optical system in which the optical axis and normal vector at the vertex of each surface do not match. The most important specification in an optical system is its focal length. Among the various methods for measuring the focal length, the most suitable method for the off-axis system is the method that adopts magnification. However, head-mounted display (HMD) optics must be measured while considering the virtual image distance, which is not infinity owing to product characteristics. For the virtual image distance, a camera with a focusing function was used. By measuring HMD optics via this magnification method, the error generated in this measurement was 0.68% of the HMD's focal length, which is within the 1%-3% range of the conventionally permitted design error for the focal length allowed at the optical design stage. Therefore, it can be verified that the measurement accuracy of the method proposed in this study is sufficiently feasible in practice.

• Journal of the Korean Society for Precision Engineering
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• v.14 no.11
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• pp.118-125
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• 1997

Non-contacting optical microscopes are increasingly used in recent industrial applications of probes for coordinate measuring machines. They have been found more efficient than conventional touch trigger porbes with ball tips especially in inspecting small-sized objects. There are two major factors affecting measuring accuracy: (1) geometric relations between coordinate systems, (2) magnification ratios of a microscope. In order to determine the magnification ratios exactly, optical imaging of edge was theroretically analyzed and practically adopted to image processing for edge detection. In addition, this paper proposes a geometric calibration method to obtain exact coordinates of measured points from the relations between the machine coordinate system and the image. In the method, the error according to the squareness between the machine axises was also removed. The method was practically adopted to a real coordinate measuring machine. An ultraprecision measurement of 0.2 um uncertainty can be practically achieved.

• Proceedings of the Optical Society of Korea Conference
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• 2006.07a
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• pp.475-476
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• 2006

• Journal of the Korea Society of Computer and Information
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• v.16 no.11
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• pp.95-102
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• 2011

Interpolation schemes are used widely in image magnification. Magnified image generated by interpolation scheme is composed of the known pixels in input image and the interpolated pixels estimated from the known pixels in input image. So, as the interpolated pixels are estimated to have locality which exists in real images, the magnified image is much closer to the real image. In this paper, an efficient interpolation scheme was proposed to provide locality for the interpolated pixels by using the characteristics of adjacent pixels in input image. The quality of magnified image using the proposed scheme was improved. In experiment, PSNR(Peak Signal to Noise Ratio) was used to evaluate the performance of the proposed scheme. The PSNR's of the magnified images generated by the proposed scheme were greater than those of the magnified images generated by the previous interpolation methods.

• Applied Microscopy
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• v.35 no.4
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• pp.98-104
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• 2005

A FOV (field-of-view) of the HV-MSC (high voltage multi-scan CCD, $1024{\times}1024$ pixels) camera mounted in the post-column HV-GIF (high voltage gatan image filter) has been drastically enlarged by the projection lens current adjustment. An imaging area of the HV-MSC camera obtained at the lowest magnification (2,000x) is $112{\mu}m^2$ which corresponds to the recording area of the film at the magnification of 8,800x, while the achievable recording area is only $0.43{\mu}m^2$ at the same magnification without this technique. Ignoring the image distortion of less than 5%, we have designed an on-site reference graph to estimate projection lens currents for microscope magnifications above 8,800x, where the recording area on the HVMSC is same as that on the film.

• Journal of the Korea Society of Computer and Information
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• v.3 no.2
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• pp.139-146
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• 1998

This paper proposes a regularized iterative image restoration using method of conjugate gradient considering a priori information. Compared with conventional regularized method of conjugate gradient, this method has merits to prevent the artifacts by ringing effects and the partial magnification of the noise in the course of restoring the image degraded by blur and additive noise. Proposed method applies the constraints to accelerate the convergence ratio near the edge portions, and the regularized parameter suppresses the magnification of the noise. As experimental results, I show the superior convergence ratio and the suppression by the artifacts of the proposed method compared with conventional methods.

• Journal of the Korean Society of Clothing and Textiles
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• v.32 no.5
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• pp.800-807
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• 2008

The purpose of this study is to compare the subjective texture of actual objects and their picture images on the Internet to find out a method to present visual images in order to supply information similar real objects. For this study, seven knit fabrics and four presentation methods of visual images including twice magnifications and two dimensions of 2D and 3D. The results of this study were as follows: There are significant differences among subjective textures evaluated by touching seven fabrics actually and we can verify the effects of fiber contents and loop length of knit on textures. We can find out differences of texture depending on presentation methods. In case of 2D evaluation of knits fabrics, visual images of real size present a little exact information on roughness and heaviness whereas those of twice magnification do roughness, wetness, softness and luster. And 3D images give us more exact information of textures on softness, heaviness and warmness, but rather twice enlarged 3D image can't supply an information of heaviness texture.

• 제어로봇시스템학회:학술대회논문집
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• 2002.10a
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• pp.41.5-41
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• 2002

This paper presents a feature extraction algorithm for vision-based micromanipulation. In order to guarantee of the accurate micromanipulation, most of micromanipulation systems use vision sensor. Vision data from an optical microscope or high magnification lens have vast information, however, characteristics of micro image such as emphasized contour, texture, and noise are make it difficult to apply macro image processing algorithms to micro image. Grasping points extraction is very important task in micromanipulation because inaccurate grasping points can cause breakdown of micro gripper or miss of micro objects. To solve those problems and extract grasping points for micromanipulation...

• Journal of Dental Rehabilitation and Applied Science
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• v.29 no.3
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• pp.249-258
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• 2013

The purpose of this study was to investigate how image magnification in dental panoramic radiography is influenced by object position. Five metal balls (4 mm in diameter, 2 for the anterior and 3 for the posterior region on the right side) were placed above alveolar crest of dry skull considering extraction socket and dental arch. Dry skull was radiographed using OP-100D (Instrumentarium Imaging Co., Tuusula, Finland) at proper and displaced position along the sagittal and transverse plane at 3 mm, 6 mm, 9 mm, 12 mm and 15 mm using special mount which can control precise movement. Images were stored in DICOM files and were measured by ruler equipped within INFINITT PACS software (Infinitt Co., Ltd., Seoul, Korea). The mean horizontal magnification was 1.224-1.439 and mean vertical magnification was 1.286 - 1.345 at proper position. Vertical magnification resulted in less variation (1.245-1.418) than horizontal magnification (0.798-6.297) according to the sagittal and transverse displacements. Head positioning is important for linear measurement on panoramic radiography and inclusion of standard object (for instance, metal ball) is helpful to anticipate exact magnification of panoramic radiographs at various location.

• Journal of the Korea Institute of Military Science and Technology
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• v.19 no.3
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• pp.288-293
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• 2016

Electronic Image Stabilization(EIS) is widely used as a technique for correcting a shake of an image. The case requiring the EIS function has been increased in high magnification thermal image observation on portable military equipment. Projection Algorithm(PA) for EIS is easy to implement but its performance is sensitive to the projection area. Especially, projection profiles of thermal image have very modest change and are difficult to extract image shifts between frames. In this paper, we proposed algorithm to extract a feature image for the thermal image and compared Block Matching Algorithm(BMA) with PA using our proposed feature image. When using our proposed feature image, BMA was simply implemented using FPGA's internal small memory. And we were able to obtain 30 % PSNR improved results compared to PA.