Floyd–Steinberg dithering is a technique that reduces the number of colours in an image while minimising visible banding. When a pixel's true colour is rounded to the nearest available palette value, the rounding error is distributed to four neighbouring pixels — 7/16 to the right, 3/16 to the lower-left, 5/16 below, and 1/16 to the lower-right. This spreads quantisation errors across the image, producing a natural-looking grain that the human eye integrates into a perception of smooth tones. The algorithm was published by Robert Floyd and Louis Steinberg in 1976.

Stippling — rendering images with variable-density dots — has been used in engraving and scientific illustration for centuries, and appears in medical textbooks, botanical drawings, and topographic maps where fine ink control is essential. In modern digital contexts, stipple-style rendering is popular in editorial illustration, tattoo design, and portrait art. Algorithms similar to the one in this simulation are also used by pen plotters, which physically draw each dot on paper using a robotic arm.

No, though they look similar. Pixel art is created manually or procedurally at a deliberately small canvas size, then scaled up. A photomosaic averages the colour of each rectangular cell of an existing image and replaces it with a solid tile (or a matching thumbnail image in traditional photomosaics). The result depends entirely on the source photo, whereas pixel art is an independent creative output. This simulation uses the averaging approach, optionally substituting circle-fill glyphs to give a tile-like effect.

ASCII art emerged in the 1960s alongside early line printers and teletypes, which could only output text characters but were used by programmers to produce pictures. It became a widespread culture on early bulletin board systems (BBS) in the 1980s and 1990s, where low-bandwidth connections made text-based images practical. The formal study of optimal character-to-brightness mappings for ASCII rendering has been explored in computer science literature since the early 1990s, including work on adaptive character ramps for different fonts.

Related techniques include halftone screening (used in CMYK printing, where dot size varies with tone), Voronoi stippling (distributing dots using weighted centroid relaxation for more even spacing), ordered dithering with Bayer matrices (an alternative to Floyd–Steinberg that produces a regular crosshatch pattern), and colour quantisation algorithms such as median-cut and k-means clustering. All of these appear in image editors, print workflows, and generative art libraries, and share the same core challenge: representing continuous tones with a limited set of discrete output values.

Floyd–Steinberg and similar dithering algorithms are built into e-ink display drivers to render greyscale images on screens that can only show black or white per pixel. They are used in GIF and PNG colour-reduction pipelines, in audio (1-bit DACs use noise shaping, the audio equivalent of dithering), and in printing — laser printers dither each page to simulate grey tones using only black toner dots. Modern image editors like Photoshop and GIMP expose dithering options whenever you reduce an image to indexed colour mode.

Current research and practice extends these ideas into neural and generative directions: neural style transfer uses convolutional neural networks to impose artistic textures on photographs; diffusion models can re-imagine photos in arbitrary styles from text prompts; and differentiable rendering allows artistic rendering pipelines to be trained end-to-end. For stippling specifically, researchers have developed Weighted Linde–Buzo–Gray (WLBG) stippling, which uses Lloyd relaxation on a density field derived from the image to place dots with near-optimal perceptual uniformity — a significant improvement over the simple grid approach used in this simulator.