Contrast sensitivity

Contrast Sensitivity S For this purpose a test piece is used whose least material thickness to be resolved in the video signal corresponds to the contrast sensitivity. The test piece can be a step/hole image quality indicator as per EN 462-2. 

In general, the performance of a radioscopic system should always be checked via test pieces with natural flaws. To ensure an additional comparability, standardized image quality indicators have to be used to control the essential image quality parameters such as spatial resolution (unsharpness) and contrast sensitivity. 

Contrast Sensitivity For monitoring purposes, a step wedge is to be used that consists of the same material as the workpiece. In addition, IQIs according to EN 462-1 or EN 462-2 - DIN wire penetrameters or step-hole IQIs - can be applied to ensure a comparability with radiography. 

The first step will establish certain minimum requirements for those parameters that are defined in part 1 inherent unsharpness, contrast sensitivity, distortion, and homogeneity. The result will be three different equipment classes SC1, SC2, SC3 (see table 1). 

The inspection class SB covers requirements beyond serial inspection for higher geometric resolution and contrast sensitivity (acc.EN 462). 

The influence of the reduced contrast sensitivity at low optical densities can be seen on the noise level, which increases with the wall thickness. 

The most relevant drawback of X-rays is their low contrast sensitivity. Even in CT a minimum concentration of 0.5 mg iodine/ml is required to achieve a detectable change of about 10-15 HU and ten times this concentration would be desirable. 0.5 mg iodine/ml corresponds to a 1 4 mM concentration of a molecule labeled with 1-3 iodine atoms. 

Valence tautomerization to the bicyclic azetine (47 R1 = OEt, R2 = Me) has been observed in the photosensitized (PlfcCO or PhCOMe) ring contraction of the otherwise photostable 2-ethoxy-4,5-dihydro-3.H-azepine (46 R4 = OEt, R2 = Me) (71JOC1934). In contrast, sensitized photolysis of the dimethylamino derivative (46 R1 = NMe2, R2 = H) gave only polymers. Unsensitized photolysis in pyrex yields several cyclic products, all of which are attributable to the intermediacy of an unstable 7-azabicyclo[3.2.0]hepta-3,6-diene (47 R1 = NMe2, R2 = H) (73CC327). 

Muth, E.R., Laurent, J.M., and Jasper, P., The effect of bilberry nutritional supplementation on night visual acuity and contrast sensitivity, Alternative Medicine Review A Journal of Clinical Therapeutic, 5, 164-173, 2000. 

Several studies have looked at schizophrenia spectrum disorders and results have been less clear than for first-degree relatives. For instance, coherent motion thresholds, PI amplitude, contrast sensitivity, and form and trajectory discrimination were not impaired (Farmer et al., 2000 O Donnell et al., 2006 Vohs et al., 2008) in schizotypal personality disorder. However, a backward masking deficit was found in schizotypal personality disorder (Cadenhead et al., 1999). 

Cimmer C, Szendi I, Csifcsak G, et al. 2006. Abnormal neurological signs, visual contrast sensitivity, and the deficit syndrome of schizophrenia. Prog Neuropsychopharmacol Biol Psychiatry 30 1225-1230. 

Jindra LF, Zemon V. 1989. Contrast sensitivity testing A more complete assessment of vision. J Cataract Refract Surg 15 141-148. 

Slaghuis WL. 1998. Contrast sensitivity for stationary and drifting spatial frequency gratings in positive- and negative-symptom schizophrenia. J Abnorm Psychol 107 ... 

Slaghuis WL. 2004. Spatio-temporal luminance contrast sensitivity and visual backward masking in schizophrenia. Exp Brain Res 156 196-211. 

Slaghuis WL, Thompson AK. 2003. The effect of peripheral visual motion on focal contrast sensitivity in positive- and negative-symptom schizophrenia. Neuropsychologia 41 968-980. 

The effect of bilberry on night visual acuity (VA) and night contrast sensitivity (CS) was examined by using a double-blind, placebo-controlled, and... 

Enroth-Cugell C, Robson JG (1966, Dec) The contrast sensitivity of retinal ganglion cells of the cat. J Physiol 187(3) 517-552... 

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