• Proceedings of the Korean Printing Society Conference
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• 2000.04a
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• pp.45-55
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• 2000

Recently, as the prepress mainstream is changed to the digital wolkflow, various digital proofing systems such as high price dye sublimation printers and low price ink jet printers are widely used in printing industry. Generally, CRT monitors are also often used as a soft proofing device for hard-copy image output. However, displayed color image on CRT monitor does not match to the actual color printing sheets. Because, the color space of CRT monitor used RGB color space, and it is differ with printing device color space, CMY. Therefore, proper color compensations are needed to match the colors between hard-copy proofs on the printing device and soft copy proofs on the monitor. For the proper compensation, we used LUT and gamut mapping method for color space transformation between device dependent color space and device independent color space, vis a vis. This paper shows the application method and the usefulness of CRT monitor for the soft-copy proofing using the output characteristics of printing device.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 1999.06a
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• pp.125-131
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• 1999

In this paper, we address practical methods for calculating camera lens distortion for real time applications. Although the lens distortion problem can be easily ignored for constant-parameter lenses, in the field of real-time camera calibrations, for zoom lenses a large number of calculations are needed to calculate the distortion. However, if the distortion can be calculated independently of the other camera parameter, we can easily calibrate a camera without the need for a large number of calculations. Based on Tsai's camera model, we propose two different methods for calculating lens distortion. These methods are so simple and require so few calculations that the lens distortion can be rapidly calculated even in real-time applications. The first method is to refer to the focal length - lens distortion Look Up Table(LUT), which is constructed in the initialization process. The second method is to use the relationship between the feature points found in the image. Experiments were carried out for both methods, results of which show that the proposed methods are favorably comparable in performance with non-real full optimization method.

• Proceedings of the IEEK Conference
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• 2002.06d
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• pp.307-310
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• 2002

Color reproductions in most ink jet printer are quite different from that of standard CRT (cathode ray tube) monitor display because of the nonlinear characteristic in subtractive color reproduction. Gray scale CCT(correlated color temperature) reproductions in a typical printer are vary with the input RGB level. A simple method for making constant gray scale CCT and gamma value in photo paper is proposed in this paper. The compensation of the CCT with white point of the photo paper under the CIE standard illuminant D65 and color correction has been confirmed using the LUT(look-up table) to compensate the CCT and gamma curve characteristic.

• 한국정보디스플레이학회:학술대회논문집
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• 2007.08a
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• pp.997-1000
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• 2007

Achieving white balance is one of the key issues for LCD image quality enhancement. A well-known color correction algorithm is Accurate Color Capture (ACC). Determination of ACC correction values has been time consuming as past methods have required trial-and-error analysis of differences between predicted and measured values. We propose a new ACC value determination method that uses spatially emulated patterns and measured values on patterns.

• Journal of the Korean Graphic Arts Communication Society
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• v.18 no.2
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• pp.69-82
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• 2000

Recently, as the prepress mainstream is changed to the digital workflow, various digital proofing systems such as high price dye sublimation printers and low price ink jet printers are widely used in printing industry. CRT monitors are also often used as a soft proofing device. However, it is very difficult to match the color image displayed on CRT monitors to the actual images printed on papers, because the color space of CRT monitors is RGB color system, and it is different with the CMY color system of the printing devices. Therefore, proper color compensations are needed to match the colors between hard-copy proofs on the printing device and soft copy proofs on CRT monitors. This paper shows the LUT and gamut mapping method considering the printing characteristics of output device is useful for the compensation.

• 한국정보통신설비학회:학술대회논문집
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• 2008.08a
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• pp.323-326
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• 2008

This paper describes some field multiplication algorithm over GF($2^m$) on 8-bit processor. Through performance comparisons among algorithm, we show that our proposal is faster than existing algorithms. The proposed algorithm save 26.38% of running time compared with naive comb multiplication algorithm which is a kind of lookup-table (LUT) based algorithm. With the proposed algorithm, a scalar multiplication over GF($2^{163}$) can be computed within 1.04 secs on 8-bit MICAz sensor mote.

• Korean Journal of Remote Sensing
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• v.23 no.3
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• pp.171-179
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• 2007

Hyperspectral images have shown a great potential for the applications in resource management, agriculture, mineral exploration and environmental monitoring. However, due to the large volume of data, processing of hyperspectral images faces some difficulties. This paper introduces the development of an image processing tool (HYVIEW) that is particularly designed for handling hyperspectral image data. Current version of HYVIEW is dealing with efficient algorithms for displaying hyperspectral images, selecting bands to create color composites, and atmospheric correction. Three band-selection schemes for producing color composites are available based on three most popular indexes of OIF, SI and CI. HYVIEW can effectively demonstrate the differences in the results of the three schemes. For the atmospheric correction, HYVIEW utilizes a pre-calculated LUT by which the complex process of correcting atmospheric effects can be performed fast and efficiently.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.19 no.12
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• pp.1339-1349
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• 2008

In this paper, a nonlinear relationship between an input complex envelope and an output complex envelope of m-th harmonic zone is theoretically analyzed, and AM/$AM_m$ and AM/$PM_m$ are defined. A scheme to extract these characteristics from measured in-phase and quadrature-phase data is suggested. The proposed analysis is verified with a fundamental-fundamental and fundamental-third harmonic measurements for a InGaP power amplifier(PA). Based on the harmonic-band nonlinear analysis and extraction scheme, a new technique to send a signal in m-th harmonic band with a harmonic signal Linearization Digital Predistortion(DPD) scheme is presented. A numerical analysis and a Look-Up Table(LUT) based DPD algorithms to linearize output signal on m-th harmonic zone are developed. For a 16- and a 64-QAM input signals, a DPD for third harmonic signal linearization is implemented, and output spectrum and signal constellation are measured. The wholly distorted signals are linearized, and thus the measured Error Vector Magnitudes (EVM) are 6.4 % and 6.5 % respectively. The results show that a proposed scheme linearizes a nonlinearly distorted harmonic band signals. The proposed nonlinear analysis and predistortion scheme can be applied to multiband transmitter in next generation software defined radio(SDR)/cognitive radio(CR) wireless system.

• Journal of the Korean Society of Radiology
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• v.15 no.4
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• pp.409-414
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• 2021

In order to acquire an image from a gamma camera, linearity correction must be performed. To this end, digital coordinates are acquired by using a linearity map to accurately specify the location where the scintillator and gamma rays interact. In this study, a method for acquiring undistorted images and digital coordinates was developed using a lookup table and maximum likelihood position estimation without using a linearity map. The proposed method was verified by configuring a small gamma camera through DETECT2000 simulation. A gamma camera was constructed using a GAGG scintillator and a SiPM optical sensor, and a gamma-ray interaction was generated at the center of the scintillator, and a lookup table was prepared using the ratio of the signals obtained from the SiPM. Through the prepared lookup table and the maximum likelihood position estimation, the position of the signal obtained by the gamma-ray interaction was acquired as digital coordinates to compose an image. As a result, the linearity was maintained compared to the generally acquired image, the accuracy of the location where the gamma-ray interaction was generated was excellent, and the distance between the locations was uniform. Since the lookup table obtained through simulation is created using the ratio of the signal, it can be directly used in the experiment, and the position of the signal can be conveniently obtained with digital coordinates with corrected linearity without creating a linearity map.

• The Journal of the Korea Contents Association
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• v.10 no.6
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• pp.329-335
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• 2010

Digital imaging detectors can use a variety of detection materials to convert X-ray radiation either to light or directly to electron charge. Many detectors such as amorphous silicon flat panels, CCDs, and CMOS photodiode arrays incorporate a scintillator screen to convert x-ray to light. The digital radiography systems based on semiconductor detectors, commonly referred to as flat panel detectors, are gaining popularity in the clinical & hospital. The X-ray detectors are described between a-Silicon based indirect type and a-Selenium based direct type. The DRS of detectors is used to convert the x-ray to electron hole pairs. Image processing is described by specific image features: Latitude compression, Contrast enhancement, Edge enhancement, Look up table, Noise suppression. The image features are tuned independently. The final enhancement result is a combination of all image features. The parameters are altered by using specific image features in the different several hospitals. The image in a radiological report consists of two image evaluation processes: Clinical image parameters and MTF is a descriptor of the spatial resolution of a digital imaging system. We used the edge test phantom and exposure procedure described in the IEC 61267 to obtain an edge spread function from which the MTF is calculated. We can compare image in the processing parameters to change between original and processed image data. The angle of the edge with respect to the axes of detector was varied in order to determine the MTF as a function of direction. Each MTF is integrated within the spatial resolution interval of 1.35-11.70 cycles/mm at the 50% MTF point. Each image enhancement parameters consists of edge, frequency, contrast, LUT, noise, sensitometry curve, threshold level, windows. The digital device is also shown to have good uniformity of MTF and image parameters across its modality. The measurements reported here represent a comprehensive evaluation of digital radiography system designed for use in the DRS. The results indicate that the parameter enables very good image quality in the digital radiography. Of course, the quality of image from a parameter is determined by other digital devices in addition to the proper clinical image.