CMY printing involves mixtures of three primary colours of dyes or inks – cyan (C), magenta (M) and yellow (Y).
There are two distinct types of CMY digital printing, one involves using solid areas of translucent colour, and the other involves halftoning.
CMY colour printing using solid areas of translucent colour applies each of the CMY inks to paper in separate layers of solid colour, creating the appearance of different colours and shades by varying the amount of each ink that is applied.
Halftoning involves dividing each image into a grid of tiny dots and printing each dot in a single colour (typically CMYK) at a fixed size and spacing to create the appearance of different shades and colours.
CMY printing using solid areas of translucent colour can produce less intense or vibrant colours than would be obtained with opaque ink because the translucent inks allow some of the white paper to show through.
Halftoning is the most common method of colour printing used in modern printers, as it allows for high-quality, photo-realistic images to be printed with relatively simple equipment.
In practice, black ink is often added to the CMY inks to improve the depth and clarity of dark areas in the image. This combination of CMYK inks is often used in printing to produce full-colour images with accurate colour reproduction.
Some effects can not be produced using the CMY colour model or CMYK printing.
Screen printing, for example, can use a wide variety of ink types, including spot colours, metallic inks, and special effects inks to achieve results that are unachievable using the standard CMY colour model.
In screen printing, each colour layer is printed separately, and this method often uses spot colours (premixed inks of a specific hue) instead of relying on CMY colour mixing. This allows for more accurate colour matching and vibrant, solid colours.
The use of spot colours can be when only a few colours are needed, as it reduces the number of screens and printing passes required compared to using CMYK colour separation.