Glossary - O

OCR

(Optical Character Recognition) - a special kind of scanner which provides a means of reading printed characters on documents and converting them into digital codes that can be read into a computer as actual text rather than just a picture.

Offset printing

The most common commercial printing technology in use today. Offset printing applies layers of ink on the page. For each layer, a reverse image of the page is placed on a roller in the printing press. Ink is applied to the non-image areas on the roller, so that as the roller presses against paper moving through the press, the proper image is left on the paper.

Open Prepress Interface (OPI)

A set of PostScript language comments for defining and specifying the placement of images on an electronic page layout.

Opacity

Term used to describe the degree to which paper will show print through.

Orphan

Line of type on its own at the top or bottom of a page.

Overlay

A transparent sheet used in the preparation of multi-colour artwork showing the colour breakdown.