Going dotty about halftone printing

Today we celebrate the birthday of Frederic Eugene Ives (17 Feb 1856 – 27 May 1937), the American photographer who patented the first successful method for halftone photographic printing.

The halftone process was an innovative new way of reproducing photographs in the printed press that enabled printers to produce different shades of grey, as opposed to the basic black and white line-drawings that was the norm until Ives’ invention.

The Ives halftone process basically involved converting a photograph into a pattern of black dots. Darker areas in the photograph were represented by larger dots placed close together, while lighter areas were made up of tiny, spread-out dots. By varying the size and distribution of the black dots, an illusion of shades of grey can be created.

An image rendered as RGB colour halftone and greyscale halftone.(© All Rights Reserved)
An image rendered as RGB colour halftone and greyscale halftone. Even though the images are clearly made up of individual dots, an effect of visual continuity is created when viewed from a distance. (Click on the image for a larger view.)
(© All Rights Reserved)

Frederic Ives wasn’t the first to come up with the idea of halftone printing. William Fox Talbot, one of the great innovators in the history of photography, is credited with the original concept, but his method wasn’t practically viable.

Various screening techniques are used to break up an image into dots. The most common method, based on amplitude modulation, produces a regular grid of dots differing in size only. Other techniques can result in dots with different distributions, and even dots of different shapes.

Moving into colour imagery, Ives also became the first to make a three-colour print from halftone blocks.

The colour halftone process still forms the basis of colour printing; by repeating the halftone process for each colour in the CMYK colour space – cyan, magenta, yellow and black – the optical effect of full colour imagery is achieved thanks to the semi-opaque property of printing ink.