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Image Frame (image + frame)

Distribution by Scientific Domains
Medical Sciences60%
Engineering40%

Selected Abstracts

Optimal Representative Blocks for the Efficient Tracking of a Moving Object

JOURNAL OF FIELD ROBOTICS (FORMERLY JOURNAL OF ROBOTIC SYSTEMS), Issue 3 2004
SangJoo Kim
Optimal representative blocks are proposed for an efficient tracking of a moving object and it is verified experimentally by using a mobile robot with a pan-tilt camera. The key idea comes from the fact that when the image size of a moving object is shrunk in an image frame according to the distance between the camera of mobile robot and the moving object, the tracking performance of a moving object can be improved by shrinking the size of representative blocks according to the object image size. Motion estimation using edge detection (ED) and block-matching algorithm (BMA) are often used in the case of moving object tracking by vision sensors. However, these methods often miss the real-time vision data since these schemes suffer from the heavy computational load. To overcome this problem and to improve the tracking performance, the optimal representative block that can reduce a lot of data to be computed is defined and optimized by changing the size of the representative block according to the size of object in the image frame. The proposed algorithm is verified experimentally by using a mobile robot with a two degree-of-freedom active camera. © 2004 Wiley Periodicals, Inc. [source]

Accurate shape from focus based on focus adjustment in optical microscopy

MICROSCOPY RESEARCH AND TECHNIQUE, Issue 5 2009
Seong-O Shim
Abstract Optical microscopy allows a magnified view of the sample while decreasing the depth of focus. Although the acquired images from limited depth of field have both blurred and focused regions, they can provide depth information. The technique to estimate the depth and 3D shape of an object from the images of the same sample obtained at different focus settings is called shape from focus (SFF). In SFF, the measure of focus,sharpness,is the crucial part for final 3D shape estimation. The conventional methods compute sharpness by applying focus measure operator on each 2D image frame of the image sequence. However, such methods do not reflect the accurate focus levels in an image because the focus levels for curved objects require information from neighboring pixels in the adjacent frames too. To address this issue, we propose a new method based on focus adjustment which takes the values of the neighboring pixels from the adjacent image frames that have approximately the same initial depth as of the center pixel and then it re-adjusts the center value accordingly. Experiments were conducted on synthetic and microscopic objects, and the results show that the proposed technique generates better shape and takes less computation time in comparison with previous SFF methods based on focused image surface (FIS) and dynamic programming. Microsc. Res. Tech., 2009. © 2008 Wiley-Liss, Inc. [source]

CONTROL ISSUES IN HIGH-SPEED AFM FOR BIOLOGICAL APPLICATIONS: COLLAGEN IMAGING EXAMPLE

ASIAN JOURNAL OF CONTROL, Issue 2 2004
Q. Zou
ABSTRACT This article considers the precision positioning problem associated with high-speed operation of the Atomic Force Microscope (AFM), and presents an inversion-based control approach to achieve precision positioning. Although AFMs have high (nanoscale) spatial resolution, a problem with current AFM systems is that they have low temporal resolution, i.e., AFM imaging is slow. In particular, current AFM imaging cannot be used to provide three-dimensional, time-lapse images of fast processes when imaging relatively-large, soft samples. For instance, current AFM imaging of living cells takes 1,2 minutes (per image frame) , such imaging speeds are too slow to study rapid biological processes that occur in seconds, e.g., to investigate the rapid movement of cells or the fast dehydration and denaturation of collagen. This inability, to rapidly image fast biological processes, motivates our current research to increase the operating speed of the AFM. We apply an inversion-based feedback/feedforward control approach to overcome positioning problems that limit the operating speed of current AFM systems. The efficacy of the method, to achieve high-speed AFM operation, is experimentally evaluated by applying it to image collagen samples. [source]

Aortic Valve Closure: Relation to Tissue Velocities by Doppler and Speckle Tracking in Patients with Infarction and at High Heart Rates

ECHOCARDIOGRAPHY, Issue 4 2010
Ph.D., Svein A. Aase M.Sc.
Aim: To resolve the event in tissue Doppler (TDI)- and speckle tracking-based velocity/time curves that most accurately represent aortic valve closure (AVC) in infarcted ventricles and at high heart rates. Methods: We studied the timing of AVC in 13 patients with myocardial infarction and in 8 patients at peak dobutamine stress echo. An acquisition setup for recording alternating B-mode and TDI image frames was used to achieve the same frame rate in both cases (mean 136.7 frames per second [FPS] for infarcted ventricles, mean 136.9 FPS for high heart rates). The reference method was visual assessment of AVC in the high frame rate narrow sector B-mode images of the aortic valve. Results: The initial negative velocities after ejection in the velocity/time curves occurred before AVC, 44.9 ± 21.0 msec before the reference in the high heart rate material, and 25.2 ± 15.2 msec before the reference in the infarction material. Using this time point as a marker for AVC may cause inaccuracies when estimating end-systolic strain. A more accurate but still a practical marker for AVC was the time point of zero crossing after the initial negative velocities after ejection, 5.4 ± 15.3 msec before the reference in high heart rates and 8.2 ± 12.9 msec after the reference in the infarction material. Conclusion: The suggested marker of AVC at high heart rate and in infarcted ventricles was the time point of zero crossing after the initial negative velocities after ejection in velocity/time curves. (Echocardiography 2010;27:363-369) [source]

Accurate shape from focus based on focus adjustment in optical microscopy

MICROSCOPY RESEARCH AND TECHNIQUE, Issue 5 2009
Seong-O Shim
Abstract Optical microscopy allows a magnified view of the sample while decreasing the depth of focus. Although the acquired images from limited depth of field have both blurred and focused regions, they can provide depth information. The technique to estimate the depth and 3D shape of an object from the images of the same sample obtained at different focus settings is called shape from focus (SFF). In SFF, the measure of focus,sharpness,is the crucial part for final 3D shape estimation. The conventional methods compute sharpness by applying focus measure operator on each 2D image frame of the image sequence. However, such methods do not reflect the accurate focus levels in an image because the focus levels for curved objects require information from neighboring pixels in the adjacent frames too. To address this issue, we propose a new method based on focus adjustment which takes the values of the neighboring pixels from the adjacent image frames that have approximately the same initial depth as of the center pixel and then it re-adjusts the center value accordingly. Experiments were conducted on synthetic and microscopic objects, and the results show that the proposed technique generates better shape and takes less computation time in comparison with previous SFF methods based on focused image surface (FIS) and dynamic programming. Microsc. Res. Tech., 2009. © 2008 Wiley-Liss, Inc. [source]