Edge enhancement

A variation on the conventional technique of x-radiography is xeroradiography, where imaging is obtained by electrostatic rather than photographic means. Because of special merits such as edge enhancement and improved texture rendition, this technique has certain advantages, eg, in the study of ceramics (39). 

Fig. 5.3.6 j oint spatial-velocity images of xenon undergoing Poiseuille flow in a pipe (id = 4 mm, Vave = 27 mm s 1, D = 8 mm2 s 1) at 0.7 atm recorded with a protocol shown in Figure 5.3.4(A). Only particles at walls are selected by the edge enhancement filter . A modified imaging gradient time duration... 

Figure 8.24. Demonstration of the edge-enhancement principle built into the chord length distribution, (a) Two-phase structure intersected by a straight line, (b) The density along the line, (c) The derivative of the density is a sequence of 5-functions which are marking the positions of the domain edges...

If the scattering entities in our material are stacks of layers with infinite lateral extension, Eq. (8.47) is applicable. This means that we can continue to investigate isotropic materials, and nevertheless unwrap the ID intensity of the layer stack. To this function Ruland applies the edge-enhancement principle of Merino and Tchoubar (cf. Sect. 8.5.3) and receives the interface distribution function (IDF), gi (x). Ruland discusses isotropic [66] and anisotropic [67] lamellar topologies. 

The anisotropic multidimensional chord distribution (CDF) is an advancement of the IDF which is adapted to the study of highly anisotropic materials. CLD, IDF, and CDF are all based on the edge-enhancement principle devised by Mering and... 

By means of this procedure our problem is not only reduced from three to two dimensions, but also is the statistical noise in the scattering data considerably reduced. Multiplication by —4ns2 is equivalent to the 2D Laplacian89 in physical space. It is applied for the purpose of edge enhancement. Thereafter the 2D background is eliminated by spatial frequency filtering, and an interference function G(s 2,s ) is finally received. The process is demonstrated in Fig. 8.27. 2D Fourier transform of the interference function... 

The V and Ni images show that the left particle has been in the unit for a long time while the right particle is very new. In the older particle, the vanadium distribution is nearly homogeneous while the new particle shows vanadium diffusing from the external surface. This observation shows that vanadyl as well as nickel porphyrins must crack on the external catalyst skin. Vanadium migration then occurs after the metal deposit is on the catalyst surface. The Ni distribution confirms the age of the pair, but also reveals that edge enhancement persists on very old particles. This confirms that the deposited nickel has very little or no mobility in the FCC unit. 

E., Schols, D., Van Damme, J., 1998. Cutting edge enhanced anti-HIV-1 activity and altered chemotactic potency of NH2-terminally... 

The effects of skeletal trauma may be simulated by normal anatomical variations during development, projection artefacts and overlap of adjacent structures. Secondary ossification centres or irregular sites of ossification that appear fragmented are often mistaken for traumatic injury. The mach effect is a physiological form of edge enhancement created when there is an abrupt change from light to dark (radio-opaque to radiolucent) or vice versa at a concave or convex interface of a subject. Its presence at the interface of structures can simulate a fracture line. Similarly, overlap of normal structures such as skin or soft tissue folds can produce an identical appearance (Fig. 7.1). 

Fig. 14.2. Reconstruction using an edge-enhancing lung reconstruction kernel...

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