Short-pulse measurements using a streak camera are sensitive to space-charge broadening, which depends on the pulse duration and shape, and on the uniformity of photocathode illumination. An anamorphic-diffuser-based beam-homogenizing system and a space-charge-broadening calibration method were developed to accurately measure short pulses using an optical streak camera. This approach provides a...

In this paper, a novel projection onto convex sets (POCS) method is presented for the suppression of blocking and ringing artifacts in a compressed image that contains homogeneous regions. A new family of convex smoothness constraint sets is introduced, using the uniformity property of image regions. This set of constraints allows different degrees of smoothing in different regions of the image...

Abstract Traditional space-invariant regularization schemes in tomographic image reconstruction using penalizedlikelihood estimators produce images with nonuniform resolution properties. The local point spread functions that quantify the local smoothing properties of such estimators are not only space-variant and asymmetric, but are also object-dependent even for space-invariant systems. We pro...

Quantitative image quality analysis technologies have advanced significantly in the past twenty years. Practical instruments for objective analysis of engineering quality attributes are now used widely and successfully in the digital printing industry. However, in the design and optimization of an imaging system, measurement of engineering quality alone is not sufficient. It is equally if not m...

The condition of the filtering screens used for separating sugar crystals and molasses in continuous centrifugals has a major influence on sugar losses, separating efficiency and throughput. Several methods, which characterize screen quality in terms of the slot width, uniformity, per cent open area and the resistance to fluid flow have been assessed by Sugar Research Institute. These are a pho...

Intrinsic flood field uniformity is a fundamental quality control test that is considered as prerequisite for performing clinical routine exams using the gamma camera. Every gamma camera vendor provides recommended geometrical and physical parameters that should be followed while performing this test. Conventional methods using NEMA recommended parameters also can be used as well. The aim of th...

Print quality demands for coated papers are steadily growing, and achieving coating uniformity is crucial for high image sharpness, colour fidelity, and print uniformity. Coating uniformity may be divided into two scales: coating thickness uniformity and coating microstructure uniformity, the latter of which includes pigment, pore and binder distributions within the coating layer. This thesis c...

UNLABELLED We determined the relative effect of corrections for scatter, depth-dependent collimator response, attenuation, and finite spatial resolution on various image characteristics in cardiac SPECT. METHODS Monte Carlo simulations and real acquisition of a 99mTc cardiac phantom were performed under comparable conditions. Simulated and acquired data were reconstructed using several correc...

Let X be an algebraic variety over the algebraically closed field K and Ξ ⊆ X(K) a set of K-rational points on X. We say that a subvariety Y ⊆ Xn of some Cartesian power of X is Ξ-special if Ξn ∩ Y (K) is Zariski dense in Y . We show under certain hypotheses on Ξ, for instance, that the class of Ξ-special varieties is closed under intersections, that when subvarieties of X vary in an algebraic ...