An Etymological Dictionary of Astronomy and Astrophysics
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A measure of the ability of an optical system to reproduce (transfer) various levels of detail from the object to the image, as shown by the degree of contrast (modulation) in the image. → optical transfer function.

→ modulation; → transfer; → function.

The function that provides a full description of the imaging quality of an optical system. A combination of the → modulation transfer function (MTF) and the → phase transfer function (PTF) , the OTF describes the spatial (angular) variation as a function of spatial (angular) frequency.

→ optical; → transfer; → function.

A measure of the relative phase in the image as function of frequency. It is the phase component of the → optical transfer function. A relative phase change of 180°, for example, results in an image with the black and white areas reversed.

→ phase; → transfer; → function.

The mathematical relationship between the output of a control system and its input: for a linear system, it is the Laplace transform of the output divided by the Laplace transform of the input under conditions of zero initial-energy storage.

→ transfer; → function.