• The Journal of Korean Society for Radiation Therapy
• /
• v.28 no.2
• /
• pp.123-130
• /
• 2016

Purpose : The aim of this study was to compare the differences between the volumes acquired with four-dimensional computed tomography (4DCT)images with a reconstruction image-filtering algorithm and cone-beam computed tomography (CBCT) images with dynamic phantom. Materials and Methods : The 4DCT images were obtained from the computerized imaging reference systems (CIRS) phantom using a computed tomography (CT) simulator. We analyzed the volumes for maximum intensity projection (MIP), minimum intensity projection (MinIP) and average intensity projection (AVG) of the images obtained with the 4DCT scanner against those acquired from CBCT images with CT ranger tools. Results : Difference in volume for node of 1, 2 and 3 cm between CBCT and 4DCT was 0.54~2.33, 5.16~8.06, 9.03~20.11 ml in MIP, respectively, 0.00~1.48, 0.00~8.47, 1.42~24.85 ml in MinIP, respectively and 0.00~1.17, 0.00~2.19, 0.04~3.35 ml in AVG, respectively. Conclusion : After a comparative analysis of the volumes for each nodal size, it was apparent that the CBCT images were similar to the AVG images acquired using 4DCT.

• 제어로봇시스템학회:학술대회논문집
• /
• 2004.08a
• /
• pp.1235-1238
• /
• 2004

Thresholding has been used to reduce the number of gray values in images. Typically, a single threshold value has been used, resulting in two gray level images. Image reduction of one single threshold value, however, may lose too much of the high-frequency edge information. Thus, dynamic thresholding that uses a different threshold for each pixel is preferred instead of using a single threshold value. Dynamic thresholding can preserve high frequency details as well as reduce the size of images. Since it takes long time to perform existing software dynamic thresholding in an embedded system, this paper proposes and implements a circuit by using a FPGA in order to perform a real-time dynamic thresholding,. The proposed circuit consists of two counters, and threshold look-up table, and control unit. The values of two counters determine each pixel position, the threshold look-up table converts each pixel value into other value, and the control unit generates necessary control signals. On arriving from a camera to the proposed circuit, each pixel is compared with its threshold value and is converted into other gray value. An image processing system by using the proposed circuit will be implemented and some experiments will be performed.

• Journal of IKEEE
• /
• v.11 no.4
• /
• pp.219-226
• /
• 2007

An efficient block based two-layer JPEG encoding algorithm is proposed to compress high dynamic range (HDR) images in this work. The proposed algorithm separates an input HDR image into a tone-mapped low dynamic range (LDR) image and a ratio image, which represents the quotients of the original HDR pixels divided by the tone-mapped LDR pixels. Then, the tone-mapped LDR image is compressed using the standard JPEG scheme to preserve backward compatibility and the ratio image is encoded to minimize a cost function that models the perception of each block with different quantization parameters in the human visual system (HVS). Simulation results show that the proposed algorithm provides better performance than the conventional method, which encodes the ratio image without any prior information of blocks.

• The Journal of the Acoustical Society of Korea
• /
• v.28 no.4
• /
• pp.370-374
• /
• 2009

In this paper, we presents a new cone beam computerized tomography (CB CT) system for the reconstruction of 3 dimensional dynamic images. The system using cone beam has less the exposure of radioactivity than fan beam, relatively. In the system, the reconstruction 3-D image is reconstructed with the radiation angle of X-ray in the image processing unit and transmitted to the monitor. And in the image processing unit, the Three Pass Shear Matrices, a kind of Rotation-based method, is applied to reconstruct 3D image because it has less transcendental functions than the one-pass shear matrix to decrease a time of calculations for the reconstruction 3-D image in the processor. The new system is able to get 3~5 3-D images a second, reconstruct the 3-D dynamic images in real time.

• Journal of the Korean Solar Energy Society
• /
• v.21 no.2
• /
• pp.69-78
• /
• 2001

This paper introduces the physical phenomena involved in Direct Contact Heat Exchangers (DCHXs) and also investigates the possibility of applying of EIT(Electrical Impedance Tomography) technique for capturing the images of dispersed phases as they stream through a stagnant body of water. A number of cases are studied where two dimensional cross-sectional static images are given for fictitious and actual masses present in a column of water(saline solution). In most direct contact liquid-liquid heat exchangers, oil or hydrocarbon with a density different(lighter or heavier) from water is normally used as dispersed working fluid. The main difficulty that arises with this arrangement lies in the elucidation of complicated flow field where the dispersed phase fluid tends to change its shape and size constantly during its journey through the other phase(water). This paper presents a number of results with different types of dispersed phases that are immiscible with water. The EIT technique has been employed in this context to test its applicability in capturing the dynamic images of dispersed phases. It shows static images of dispersed phases where dynamic images could be obtained by simply extending the algorithms and strategies employed in the present analysis.

• Journal of Magnetics
• /
• v.19 no.4
• /
• pp.365-371
• /
• 2014

The aim of this study was to evaluate the utility of 3-D images by comparing and analyzing reconstructed 3-D images from fast spin echo images of MRI cholangiopancreatography (MRCP) images using maximum intensity projection (MIP) with the subtraction images derived from dynamic tests of magnetic resonance mammography. The study targeted 20 patients histologically diagnosed with pancreaticobiliary duct disease and 20 patients showing pancreaticobiliary duct diseases, where dynamic breast MR (magnetic resonance) images, fast spin echo imaged of pancreaticobiliary duct, and 3-D reconstitution images using a 1.5T MR scanner and 3.0T MR scanner were taken. As a result of the study, the signal-to-noise ratio in the subtracted breast image before and after administering the contrast agent and in the reconstructed 3-D breast image showed a high ratio in the reconstructed image of lesional tissue, relevant tissue, and fat tissue. However, no statistically meaningful differences were found in the contrast-to-noise ratio of the two images. In the case of the MRCP image, no differences were found in the ratios of the fast spin echo image and reconstructed 3-D image.

• Journal of radiological science and technology
• /
• v.32 no.3
• /
• pp.277-283
• /
• 2009

It is important to get clinical ultrasonic images of good quality for accurate diagnosis. In this study, it observed the change of ultrasonic images against setting frequency, dynamic range(DR) and type of probes on ultrasonic scanner. In the experiment it evaluated image of LCS (Low Contrast Sensitivity) targets(-15, -6, -3, +3, +6, +15 dB) of a standard ultrasonic test phantoms(539,551, ATS, USA) similar to solid and cystic lesions. Its imaged from convex (C3-7IM) and linear probe (L5-12IM) on SA-9900 (Medison Ltd, Korea) scanner. The images obtained altering the setting parameters which are frequency(gen, pen, res, harmonic) mode and DR($40{\sim}100\;dB$). The quality of images evaluated compare with the nominal LCS value of target and measured LCS value. The results show that there was no significant changing of quality images altering DR 40, 60, 80, 100 dB against frequency in Convex probe but the image being the highest in LCS target at DR 60 dB, harmonic of frequency mode in the -15 dB target close to cystic lesion. In Linear probe, DR 40 dB, harmonic mode at -15 dB LCS target close to nominal value. It discussed necessity of evaluation about ROC(Receiver Operating Characteristic) from the psychological viewpoint and limit of evaluation from quantified images.

• Journal of Korea Multimedia Society
• /
• v.13 no.4
• /
• pp.526-534
• /
• 2010

This paper describes an algorithm which merges two HDR pictures taken under different exposure time to display on the LDR devices such as LCD or CRT. The proposed method does not generate the radiance map, but directly merges using the weights computed from the input images. The weights are firstly produced on the pixel basis, and then blended with a Gaussian function. This process prevents some possible sparkle noises caused by radical change of the weights and contributes to smooth connection between 2 image informations. The chrominance informations of the images are merged on the weighted averaging scheme using the deviations of RGB average and their differences. The algorithm is characterized by the feature that it represents well the unsaturated area of 2 original images and the connection of the image information is smooth. The proposed method uses only 2 input images and automatically tunes the whole internal process according to them, thus autonomous operation is possible when it is included in HDR cameras which use double shuttering scheme or double sensor cells.

• The Journal of the Institute of Internet, Broadcasting and Communication
• /
• v.20 no.6
• /
• pp.123-128
• /
• 2020

In this paper, we presents a new cone beam computerized tomography (CBCT) system for the reconstruction of 3 dimensional dynamic images. The system using cone beam has less the exposure of radioactivity than fan beam, relatively. In the system, the reconstruction 3-D image is reconstructed with the radiation angle of X-ray in the image processing unit and transmitted to the monitor. And in the image processing unit, the Three Pass Shear Matrices, a kind of Rotation-based method, is applied to reconstruct 3D image because it has less transcendental functions than the one-pass shear matrix to decrease a time of calculations for the reconstruction 3-D image in the processor. The new system is able to get 3~5 3-D images a second, reconstruct the 3-D dynamic images in real time. And we showed the Rotation-based method was good rather than existing reconstruction technique for 3D images, also found weakness and a solution for it.

• Journal of Biomedical Engineering Research
• /
• v.28 no.2
• /
• pp.294-299
• /
• 2007

For efficient and accurate diagnosis of ultrasound images, appropriate time gain compensation(TGC) and dynamic range(DR) control of ultrasound echo signals are important. TGC is used for compensating the attenuation of ultrasound echo signals along the depth, and DR controls the image contrast. In recent ultrasound systems, these two factors are automatically set by a system and/or manually adjusted by an operator to obtain the desired image quality on the screen. In this paper, we propose an algorithm to find the optimized parameter values far TGC and DR automatically. In TGC optimization, we determine the degree of attenuation compensation along the depth by dividing an image into vertical strips and reliably estimating the attenuation characteristic of ultrasound signals. For DR optimization, we define a novel cost function by properly using the characteristics of ultrasound images. We obtain experimental results by applying the proposed algorithm to a real ultrasound(US) imaging system. The results verify that the proposed algorithm automatically sets values of TGC and DR in real-time such that the subjective quality of the enhanced ultrasound images may be sufficiently high for efficient and accurate diagnosis.