O

Open Pre-press Interface (OPI)

A graphics management system whereby a high-resolution scanned image is placed on a server and a low-resolution version is supplied to the designers for use in visual page layout only. When it is time to run the finished job for print – or high-resolution proof – the job can be output at a high resolution and the OPI files will be picked up and sent to the imagesetter.

This is especially useful because it saves time in the design studio, as it is not necessary to spend time scanning low-resolution positionals. And it also ensures that, when the final high-resolution scan is output, it will be positioned and cropped exactly as the designer intended – no need for rescanning or manual placement.

Optical resolution

The optical graphics resolution is the real maximum resolution that an input device, such as a scanner or digital camera, can render a bitmap image. As opposed to the interpolated resolution, which is where the input device's software will enlarge the image resolution by artificially adding pixel data.

When buying a high quality flatbed scanner, or digital camera, the optical resolution is the figure that needs to be paid attention to. The maximum optical resolution is the amount that a given document can be enlarged by the scanner's hardware technology, without resorting to interpolation. Interpolating an image's resolution will result in a soft or blurry image and will not result in a high quality pre-press reproduction.

See also: difference between dots per inch & pixels per inch.