M. Antonelli, M. Di Fraia, A. Tallaire, J. Achard, S. Carrato, R. Menk, G. Cautero, D. Giuressi, W. Jark, G. Biasiol, T. Ganbold, K. Oliver, C. Callegari, M. Coreno, A. De Sio, E. Pace
New generation Synchrotron Radiation (SR) sources and Free Electron Lasers (FEL) require novel concepts of beam
diagnostics to keep photon beams under surveillance, asking for simultaneous position and intensity monitoring. To deal with high power load and short time pulses provided by these sources, novel materials and methods are needed for the next generation BPMs.
Diamond is a promising material for the production of semitransparent in situ X-ray BPMs withstanding the high dose rates of SR rings and high energy FELs. We report on the development of freestanding, single crystal CVD diamond detectors. Performances in both low and radio frequency SR beam monitoring are presented. For the former, sensitivity deviation was found to be approximately 2%; a 0.05% relative precision in the intensity measurements and a 0.1-μm precision in the position encoding have been estimated. For the latter, single-shot characterizations revealed sub-nanosecond rise-times and spatial precisions below 6 μm, which allowed bunch-by-bunch monitoring in multi-bunch operation.
Preliminary measurements at the Fermi FEL have been performed with this detector, extracting quantitative intensity and position information for FEL pulses (~ 100 fs, energy 12 ÷ 60 eV), with a long-term spatial precision of about 85 μm; results on FEL radiation damages are also reported. Due to their direct, low-energy band gap, InGaAs quantum well devices too may be used as fast detectors for photons ranging from visible to X-ray. Results are reported which show the capability of a novel InGaAs/InAlAs device to detect intensity and position of 100-fs-wide laser pulses.
Forensic science is already taking benefits from synchrotron radiation (SR) sources in trace evidence analysis.
In this contribution we show a multi-technique approach to study fingerprints from the morphological and
chemical point of view using SR based techniques such as Fourier transform infrared microspectroscopy (FTIRMS),
X-ray fluorescence (XRF), X-ray absorption structure (XAS), and phase contrast microradiography. Both
uncontaminated and gunshot residue contaminated human fingerprints were deposited on lightly doped silicon
wafers and on poly-ethylene-terephthalate foils. For the uncontaminated fingerprints an univariate approach of
functional groups mapping to model FT-IRMS data was used to get the morphology and the organic compounds
map. For the gunshot residue contaminated fingerprints, after a preliminary elemental analysis using XRF,
microradiography just below and above the absorption edge of the elements of interest has been used to map the
contaminants within the fingerprint. Finally, XAS allowed us to determine the chemical state of the different
elements. The next step will be fusing the above information in order to produce an exhaustive and easily
understandable evidence.
KEYWORDS: Image processing, Signal attenuation, RGB color model, Image compression, High dynamic range imaging, Visual system, Eye, Image quality, Visualization, Data conversion
The dynamic range of an image is defined as the ratio between the maximum and minimum luminance value
it contains. This value in real images can be several thousands or even millions, whereas the dynamic range
of consumer imaging devices rarely exceeds 100; therefore some processing is needed in order to display a high
dynamic range image correctly. Global operators map each pixel individually with the same nonlinear function;
local operators use spatially-variant functions in order to achieve a higher quality. The lower computational cost
of global operators makes them attractive for real-time processing; the nonlinear mapping can however attenuate
the image details. In this paper we define an expression which gives a quantitative measure of this artifact, and
compare the performance of some commonly used operators. We show that a modified logarithm we propose has
a satisfactory performance for a wide class of images, and has a theoretical justification based on some properties
of the human visual system. We also introduce a method for the automatic tuning of the parameters of our
system, based on the statistics of the input image. We finally compare our method with others proposed in the
literature.
In this paper we present a digital image enhancement technique which relies on the application of a nonlinear operator within the Retinex approach. The basic idea of this approach is to separate the illumination and reflectance components of the image, so that by reducing the contribution of the former it is possible to effectively control the dynamic range of the latter. However, its behaviour critically depends on the quality of the illumination estimation process, so that either annoying artifacts are generated, or very complex operators have to be used, which may prevent the use of this method in several cost- and time-sensitive applications. Our method is able to provide, thanks to the use of a suitable nonlinear operator, good quality, artifacts-free images at a limited computational complexity.
Some modifications to the filterbank algorithm for fingerprint recognition are proposed. Particular attention is paid to core localization and full database coverage. The present implementation improves recognition results while keeping almost the same computational load.
We present in this paper a novel and effective system for removing blotches in old film sequences. In particular we propose a new very efficacious detection method: it is able to yield a high correct detection rate while minimizing, at the same time, the false alarm rate. Moreover, it is very efficient also in presence of slow motion, since it exploits both temporal and spatial features of the blotches. Adaptive Block Matching is used for the blotch correction step.
A nonlinear filtering technique for the preprocessing of very low contrast images has been applied to optical profilometry, as an attempt to improve the accuracy of the measurement of objects in harsh conditions. The technique is based on the application of a nonlinear architecture composed of linear Laplacian filters followed by quadratic filters which detect correlated elements. The above sequence of operators results in efficient highpass filtering, keeping at the same time the signal-to-noise ratio within acceptable limits. When applied to highly transparent or weakly diffusive surfaces, the preelaboration technique has largely improved the accuracy of the profilometer. In this paper the preelaboration technique is presented. In particular, the influence of the nonlinear image elaboration on the overall system performance is discussed.
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