Spot colour

Also known as a solid colour, this is any colour printed with its own ink, in contrast to process colour printing which uses four inks (cyan, magenta, yellow and black – or CMYK) to produce all other colours.

Split duct process

Also known as rainbow printing. This is employed in offset printing where colours are intentionally allowed to overlap on the transfer cylinder producing a gradated effect.

Smartphone

A cellular (or mobile) telephone with an integrated computer, camera, and other features not originally associated with a mobile phone.

Spectroscopy

The analysis of the wavelength and intensity of a specific area of the electromagnetic spectrum in order to undertake a qualitative or quantitative analysis.

Speckle pattern

Produced by the mutual interference of a set of coherent wave fronts. Speckle patterns have been used in a variety of applications in microscopy, imaging, optical manipulation and document biometrics (or fingerprinting). They typically occur in diffuse reflections of...