White facsimile transmission

In telecommunication, the term white facsimile transmission has the following meanings:

1. In an amplitude-modulated facsimile system, transmission in which the maximum transmitted power corresponds to the minimum density, i.e., the white area, of the object.
2. In a frequency-modulated facsimile system, transmission in which the lowest transmitted frequency corresponds to the minimum density i.e., the white area, of the object.

Both of these terms became outmoded in the late 20th century except in specialist usage, as most fax machines now use the digital ITU-T fax standards, which encode the image digitally over a QAM-modulated signal. See also Black facsimile transmission.