contrast sensitivity

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con·trast sen·si·tiv·i·ty

in optics, the ability to discern the difference in brightness of adjacent areas; in radiology, allergic reaction to iodinated radiographic contrast medium.
Farlex Partner Medical Dictionary © Farlex 2012

contrast sensitivity

The ability to distinguish objects from the background in which they are located. It is a critical component of functionally adequate vision.
Medical Dictionary, © 2009 Farlex and Partners

sensitivity, contrast 

The ability to detect luminance contrast. In psychophysical terms it is the reciprocal of the minimum perceptible contrast. The measurement of the contrast sensitivity of the eye is a more complete assessment of vision than standard visual acuity measurement. It provides an evaluation of the detection of objects (usually sinusoidal gratings) of varying spatial frequencies and of variable contrast and thus obtaining a contrast sensitivity function (CSF). Example: following amblyopia treatment, some cases still have the same visual acuity while the CSF is improved. See contrast sensitivity chart; contrast sensitivity function; spurious resolution; Arden grating test; Vistech.
Table S1 Relationship between contrast sensitivity and contrast threshold (contrast sensitivity = 1/contrast threshold). Neither values have units
contrast threshold
contrast sensitivitylog10 contrast sensitivitydecimal%
10003.000.0010.1
1002.000.011
201.300.055
10.001.000.110
5.000.700.220
3.330.520.330
2.500.400.440
2.000.300.550
1.670.220.660
1.430.150.770
1.250.100.880
1.110.050.990
1.000.001100
Millodot: Dictionary of Optometry and Visual Science, 7th edition. © 2009 Butterworth-Heinemann
References in periodicals archive ?
As can be seen, very good results are obtained in the whole frequency band analysed, obtaining a cut-off frequency of 1.95 GHz, very close to the designed 2 GHz.
The high-pass filter is more complicated to design due to the very low (0.15 Hz) cut-off frequency. The primary purpose of this filter is to block the dominant DC background on which the PPG signal is superimposed.
The cut-off frequency of the filter must maintain some relation with the cutoff frequencies of the system.
The control system amplifies the signals in frequencies up to the cut-off frequency and damps the signals with frequencies greater than this frequency.
Power line noise can be reduced significantly by this low pass filter with a cut-off frequency of 40Hz.
Each wedge has a design length of 1.20 metres in order to achieve the specified 63Hz cut-off frequency. Depending on the nature of the measurements and the researchers' requirements, the floor can also be covered with absorbent panels to improve the overall acoustic performance of the chamber.
For cut-off frequency of 5 MHz, the values of capacitor used in Figure 7 can be calculated by (10), (12), (13), and (14) as [C.sub.v1] = 15.28 pF, [C.sub.V2] = 36.9 pF, [C.sub.V3] = 36.9 pF, and [C.sub.V4] = 15.28 pE Figure 8 shows the frequency response of the low pass fourth-order Butterworth filter.
Our cut-off frequency calculation of the first case results in an expression function of the optic axes components [[epsilon].sub.z] and [[mu].sub.z], which coincides with the conventional bi-isotropic formula [2], and it is obtained from bianisotropic one, when [[xi].sub.z] [square root of [[mu].sub.ry][[epsilon].sub.ry]] = [[xi].sub.y] [square root of [[mu].sub.ry][[epsilon].sub.rz]] and [square root of [[mu].sub.rz][[epsilon].sub.rz]] [not equal to] [absolute value of [[xi].sub.z]] The second case results in a new and interesting expression of cutoff frequency function only of the chirality parameter [[xi].sub.z], this latter cancels the direct effect of the two parameters (permeability [[mu].sub.z] and permittivity [[epsilon].sub.z]) on the cut-off frequency value.
On the one hand, the low cut-off frequency of the Vivaldi antenna was extended by RSE which indicates that it can be used as the dual-polarized antenna array element at X-band, and the radiation performance was also improved.
As observed in Figure 6, there is neither attenuation nor shift for such frequencies, so we decided to move to upper values, in order to calculate the expected cut-off frequency response.
Moreover, at PSMF-E's cut-off frequency, which is referred to as the frequency at which the low-frequency asymptote and high-frequency asymptote of gain plot intersect each other, the gain is approximately 0.8, whereas those of 2-LPF are 0.707.