[Signal-to-noise ratio or the number of perceptible grey tones in the x-ray picture. II: Information content and viewing conditions].
The information obtainable from a radiograph depends on the viewing conditions under which the radiograph is viewed. All the viewing conditions can be defined in terms of scattered light. The amount of information taken from a radiograph with S = 1000 (S = speed class) and perfect conditions is the same as that from a radiography with S = 100 viewed under poor conditions. The optimum illuminance for the radiograph viewing room is 50 lx diffuse. The influence of scattered light is small enough to cause only a small loss of information. With the illuminance of 50 lx diffuse in the viewing room and Lo = 2000 cd/m2, the density range should be delta D = 2.85. The scattered light reduces it to delta D = 2.60 when the radiograph is viewed under the above-mentioned circumstances.
Blendl
C
C
Agfa-Gevaert, V-Roe-Wiss, Leverkusen.
Kierdorf
M
M
Bollen
R
R
Freytag
K H
KH
D011859:Radiography; D013679:Technology, Radiologic