[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.

[Signal to noise ratio or the number of perceptible gray tones in the x-ray picture. I. The dependence on the system sensitivity S (DIN 6867)].

It is shown that the number of contrasts which can be differentiated on a radiograph depends on the detail size, the noise, and the viewing conditions. The minimum signal-to-noise ratio (SNR) for a perception approach is equivalently described by the SGA value. This testing method was first developed by De Belder and Bollen to examine the visibility of low contrast details.

[The influence of the spectrum and the type of exposure on the contrast of double-sided coated x-ray film].

The present article describes the circumstances concerning the use of testing aids such as sensitometers with one-sided exposure. It is shown which phenomena must be considered if radiographic films coated on both sides are exposed with a) standard pocket sensitometers (one-sided exposure), b) lab sensitometers (double-sided exposure to ANSI Ph 2.9 [1964]), c) x-radiation in the cassette, intensifying screen and film system (to DIN 6867 T 1).

The effect of vesiculectomy on seminal characteristics in the stallion.

Successful unilateral extirpation of an inflamed seminal vesicle in a stallion led to systematic trials of the influence of a reduction and absence of the secretion of this gland upon semen characteristics. Operations were performed by the method described for the bull. The volume of ejaculates dropped and sperm concentration per ml increased in each of 2 stallions from which the seminal vesicles had been uni- or bi-laterally removed.