To avoid the ghosting effect of the light field rendering caused by the insufficient sampling rate, we extend the
application of the criterion of ghost-free reconstruction from one constant-depth scenes to more complex scenes which
contain multiple depth layers. It is shown that the optimal constant depth and the maximum camera interval can be
determined by the scene geometry and the camera resolution. The relationship between them is formulated in this paper.
Also, we use an experiment to verify the criterion presented here. The mean square difference (MSD) between the
reconstructed views and the standard views are calculated to show the reconstruction quality at different camera intervals.
The quantitative data are basically in accord with the subjective observation in this experiment and the results
sufficiently support the theoretical analysis.
In order to achieve a non-contact interactive operation in particular conditions such as high-temperature, high-voltage
conditions and space capsules, a real-time indicated object recognition method is proposed in this paper. It combines
eye-finger moving information to estimate the object position. Multi-camera is used to get images containing fingertips
and eyes, and binocular vision principle is utilized to estimate the 3D position of fingertips and eyes. According to
physiological characteristic, when people indicate objects, the line linking the center of his two eyes and fingertip will
pass the object point. So after capturing eyes and fingertips in video stream images with feature point extracting
algorithm, a model from 2D image coordination to object scene coordination which can be expressed as a projective
translation with multi-view restriction is presented. Using this model, 3D position of eyes and fingertips can be estimated
from 2D positions in images, and the line linking the center of a person's two eyes and his fingertip is obtained.
Intersecting this line and the plane which the object stand on it produces the object point which is the point indicated by
the person's finger. This method estimates the absolute position of the object, which means it needn't users to provide
any initial benchmark information. Finally, this method is tested by a practical indicated object recognition system with
error analysis of camera calibration and image processing result.
Proc. SPIE. 6279, 27th International Congress on High-Speed Photography and Photonics
KEYWORDS: Signal to noise ratio, Magnetic resonance imaging, Error analysis, Image restoration, Fourier transforms, Data acquisition, Image quality, Reconstruction algorithms, Direct methods, Brain imaging
A Non-Uniform Fast Fourier Transform (NUFFT) based method for non-Cartesian k-space data reconstruction is
presented. For Cartesian K-space data, as we all know, image can be reconstructed using 2DFFT directly. But, as far as
know, this method has not been universally accepted nowadays because of its inevitable disadvantages. On the contrary,
non-Cartesian method is of the advantage over it, so we focused on the method usually. The most straightforward
approach for the reconstruction of non-Cartesian data is directly via a Fourier summation. However, the computational
complexity of the direct method is usually much greater than an approach that uses the efficient FFT. But the FFT
requires that data be sampled on a uniform Cartesian grid in K-space, and a NUFFT based method is of much
importance. Finally, experimental results which are compared with existing method are given.
Surface defection inspection methods based on machine vision have lots of advantages over many other automatic
inspection methods, such as higher flexibility, lower overall cost, etc. However, the robustness of these methods is still
unsatisfactory. Inspection of magnetic rings which are rich in texture and have various defections is a typical machinevision-
based inspection task with high difficulty. Therefore, conclusions of the research on this problem are
In this paper, factors which lead to the variation of the inspection results are classified, and then a quantitative analysis
for inspection systems introducing a new concept of robustness index is proposed. As an approach for enhancing
robustness, the effect of the algorithm rule is focused on. The author extracts defection features on three levels in
designing the rule and come to a conclusion that a complete extraction on higher level can enhance the robustness of the
system after theory analysis and experiments.
According to Sampling Theorem and image processing, structured light system has some limits, such as the
measurement resolution is restricted, some little gaps can not be measured and there are some errors or lost data on the
border of surface. A novel rotatable interlaced coding in real-time system of 3D information acquisition using structuredlight
imaging is proposed. It is consisting of two free directions of three-frame space-time light pattern, which can
acquire the denser 3D data from a single viewpoint. It can decrease the error from range image registration and advance
the system accuracy. The paper builds a real-time system of 3D profile measurement using structured-light. It allows a
hand-held object to rotate freely in the space-time coded light field, which is projected by the projector.