Where halftone, dither and glitch come from, and how to use them well

Halftone, dither and glitch are three of the most requested effects in Voidcanvas, which is why each has its own quick tool. All three began as solutions, or failures, in printing and computing before anyone treated them as style. When you know what problem a look was solving, you can tell when it fits a piece and when it is just decoration.

Halftone: photographs with one ink#

A printing press puts down ink or no ink. It cannot print grey. For most of the 1800s, newspapers could only reproduce pictures as engravings cut by hand. The halftone process changed that in the 1880s: a photograph was shot through a fine screen that broke it into dots, big where the image was dark and small where it was light. From reading distance the eye blends the dots back into tone. By the end of the century halftone photographs were a normal part of printed news.

The dots stayed visible in cheap printing, and comics used their own flat dot tints for colour. In the 1960s pop artists, Roy Lichtenstein most famously, enlarged those dots into the subject of the work. That is the association halftone still carries: print, mass media, a slightly rough edge.

Using it

The Halftone effect lays black dots on a square grid, each sized by the darkness of that patch. Dot Size sets the grid spacing: low values read as a photo from a distance, high values become graphic. Contrast sets how large the dots grow; above 50 the shadows fill in solid.

• Pick images with a clear silhouette and strong tonal range. Flat, grey photos turn to mush. Add contrast underneath first.
• Decide whether the dots are texture or subject. Fine dots suggest print; big dots make a statement.
• The result is black and white. For colour, send it to the Editor and add a Duotone filter above it to put one ink on coloured paper.
• Export PNG. JPG compression smears hard dot edges.

Dither: grey on screens that had none#

Early computer displays and printers often had one bit per pixel: each dot was on or off. Dithering fakes the missing tones by mixing on and off pixels in patterns. The best-known method, published by Robert Floyd and Louis Steinberg in 1976, works through the image pixel by pixel, rounds each one to black or white, and passes the rounding error on to the neighbours not yet visited. The result is a fine, organic scatter rather than a regular grid.

It became the look of early one-bit screens and a certain era of games and interfaces, which is why dither now reads as retro computing, zines and photocopies.

Using it

The Dither effect in Voidcanvas is Floyd-Steinberg. Its one setting, Threshold, moves the split between black and white: higher pushes more of the image dark.

• Dither works pixel by pixel with no size setting, so the full-size download of a large photo has a much finer pattern than the preview. To make the pattern visible and chunky, work at a smaller size.
• If you want no grey at all, use Threshold from the Stylize tab instead. It cuts straight to black and white for a stencil or photocopy look.
• Dither suits one-colour print and screen graphics equally. Keep it as PNG.

Glitch: when the signal breaks#

Glitch comes from failure: tape with tracking errors, a video stream that loses data and smears one frame into the next, a file opened as the wrong kind of file. Artists began provoking these errors on purpose, and by the late 2000s glitch art was a recognised practice, with writers such as Rosa Menkman arguing for the error as a medium in its own right. The look now signals technology, music and anything that wants to feel unstable.

Using it

The Glitch effect cuts the image into horizontal strips and slides about three in ten of them sideways. Offset sets how far they move, Slice Height how tall each strip is, and Randomize picks which strips move. In the quick tool, Shuffle gives a new arrangement.

• Scrub Randomize until the tears miss the parts that must read, such as eyes or a logo. Each value is repeatable, so you can note a number and come back to it.
• Thin strips look like signal noise; tall ones look like broken blocks. Match the strip height to the scale of the design.
• Related looks sit in the Distort tab: RGB Shift for colour fringes, Slice Shift when every band should move, and Pixel Sort for streaks in bright areas.
• A glitch is loud. Lower the effect's Opacity in Effects, or mask part of it in the Editor, so the error lands where it adds tension.

Keep it editable#

Each quick tool has Send to Layer Stack, which opens the Editor with your photo on one layer and the effect as a live filter layer above it, with your settings. You can still change the dot size after you have set the type, mask the effect off a face, or stack a Duotone and a grain layer on top. The downloads are rendered from your original at full size, up to 8000 pixels on the long edge, with pixel settings scaled to match the preview.

For a full print look, Make a risograph or screen-print look combines Halftone, Duotone, overprinting type and grain. The settings for every effect are in Artistic effects and Distort effects.

Try the Halftone Generator