Image resolution

Before the data can be visualised, ie displayed in a two or three-dimensional representation, the ultrasonic responses from the interior of the test-piece must be reconstructed from the raw ultrasonic data. The reconstruction process projects ultrasonic indications into 3D space. As well as reconstructing the entire ultrasonic data set within an acquisition file, it is possible to define an arbitrary sub-volume of the test object over which reconstruction will take place. The image resolution may also be defined by the user. Clearly, larger volumes or greater resolution will increase the computation time for both the reconstruction and visualisation processes. 

STEM can provide image resolution of thin specimens rivaling TEM, but in addition can provide simultaneous crystallographic and compositional analysis at a higher spatial resolution than any other widely-used technique. Any solid material may be examined, provided that a specimen can be prepared that is less than about 100 nm in thickness. 

Scanning force microscopy (SFM) is the only tool that allows one to image S-layer protein monolayers on solid supports at molecular resolution (Fig. lb and c) [22-25]. In particular, SFM in contact mode under water with loading forces in the range of <500 pN leads to an image resolution in the subnanometer range (0.5-1.0 nm). 

The absolute strength of the MRI signal depends on many factors including the number of nuclear spins in an imaging voxel. Thus, there is a tradeoff between image resolution and signal-to-noise ratio, S/N. For the commonly used granular... 

Contact lithography can be used to spatially control the photosubstitution process to form laterally resolved bicomponent films with image resolution below 10 pm. Dramatic changes occur in the colors and redox potentials of such ruthenium(II) complexes upon substitution of chloride for the pyridine ligands (Scheme 1). Striped patterns of variable colors are observed on addressing such films with a sequence of potentials. 

The resolution and sensitivity of an imaging device depend on a number of variables, for example, spatial resolution in SPECT is limited primarily by collimator resolution. Typical gamma camera SPECT systems have in-plane spatial resolution in the final reconstructed image of about 12 mm for high-resolution imaging. Resolution and sensitivity in PET is given in Table 58-3. 

Recall that the image resolution, down and Across, is inversely proportional to the size of the region of Fourier space sampled, as given by 2, where An and Av are the sizes of the sides of the sampled region. The unambiguous scene size is inversely proportional to the Fourier space sampling frequency. 

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