They image would be made up of many squares of colour base on a grid pattern, like graph paper. Q R RGB - R ed, G reen, B lue, the colours used on Colour monitors, televisions and other additive colour devices. The density of the screen changes with the size of dot. This is used for making tints of colour and doing halftone photos. Spot Colour - a specified colour of ink.
Most commercial printers use the pantone matching system to describe ink colour.
Each plate on a printing press is for one colour of ink. One plate is needed for each spot colour ,and a separate plate for any varnish. This is the preferred file format for use with documents you wish to print commercially. Scans for commercial printing should be done as CMYK if possible. CAN contain both vector and pixel information.