Design Nomenclature / Color
Dithering
Also called dither, error diffusion, ordered dither
Distributing quantization error across neighbouring pixels so a limited palette approximates colors it does not contain. Ordered dithering thresholds against a fixed matrix and shows its grid; error diffusion pushes each pixel's residue onto its unprocessed neighbours and looks organic. Both trade visible noise for the banding that plain rounding would give.
Not to be confused with
- HalftoneContinuous tone simulated by dots of varying size on a fixed grid, because a press can lay ink or not lay ink and nothing in between. Apparent value comes from the proportion of paper covered and the eye does the averaging. Screen frequency and angle decide whether it reads as tone, as pattern, or as moiré.
- BandingVisible steps in a gradient that should read as continuous, caused by too few code values across the range being covered — eight-bit encoding over a long shallow ramp is the usual culprit. Mach banding compounds it: the eye exaggerates edges, so each step acquires an illusory dark and light lip it does not have.
- PosterizationReduction of a continuous tonal range to a small number of flat steps, named after the flat-inked poster it imitates. As an effect it is a decision; as an artifact it is the same operation arriving uninvited — which is why the word does duty for both a technique and a defect and gets argued about accordingly.