As a photographic practice, sharpening has its roots in the analog world, as the sidebar above indicates. However, the analog unsharp masking technique described therein offered only two controls.
The limited control and uncertain results prevented unsharp masking from becoming a mainstream practice in analog photography. But it did see some use in sharpening analog color separations for offset printing, often by making a blurred duplicate of the continuous-tone separation, then printing it together with the sharp version as a contact print, after which the separation was screened.
Sharpening for continuous-tone photographic prints was something of a luxury, but when the continuous-tone original was turned into cyan, magenta, yellow, and black dots of ink, some of the original sharpness was lost. So sharpening became, and remains to this day, a standard operation in prepress. When the drum scanner replaced the stat camera, digital sharpening became the norm.