Halftone

Print can’t do grey

A press puts ink down or it doesn’t. There is no half-ink. Every continuous-tone image you have ever seen printed was a lie told by area: the page is covered in cells, each cell holds a mark, and the mark’s size decides what fraction of that cell is inked. Small marks with white between them read as light; marks that have grown until they touch read as dark. Your eye does the averaging.

That is a halftone screen, and it is why a magazine photograph dissolves into dots under a loupe but resolves into a face at arm’s length. Cell size sets how close you have to get before the illusion breaks.

Why the screen is rotated

An unrotated screen lines its grid up with the horizontals and verticals already in the picture — window frames, brickwork, fabric weave, the pixel grid itself — and the two regular patterns beat against each other into moiré. Turning the screen off-axis puts its frequency somewhere the image’s own structure isn’t, and the interference stops being visible.

The same problem, multiplied, is why four-colour process printing gives every plate a different angle. Four identical screens stacked on top of one another would moiré catastrophically; offset them and the interference becomes the rosette that a colour print shows under magnification. CMYK Halftone is the separate effect that does this properly, plate by plate, rather than screening the composite image once.

What the cell shape changes

Dot is the classic: a circular mark that grows with tone, neutral, and the one that reads most as “printed”. Square grows into its neighbours sooner, so midtones join up earlier and the result goes graphic faster. Line abandons the grid in one axis entirely and modulates the thickness of a ruled screen instead — the engraved, banknote-ish look. Cross is the most decorative of the four and the one that survives being scaled up largest.

Cell size, screen angle and shape are three controls doing one job between them. If a halftone looks wrong, it is almost always the angle beating against something in the picture, not the shape.

When you’d reach for it

When you want print, specifically — comic and newsprint texture, a poster that reads as reproduced rather than photographed, or an image that has to survive being blown up to a size where a photograph would fall apart and a screen just gets bigger.

Stack it under a colour treatment rather than over one. A halftone applied last screens whatever it is given; a halftone applied first gives everything after it a structure to grip.

Every option, from the app

Generated from the registry the app publishes, so this list is whatever the current build actually ships — not a copy of it.

Shape

DotLineCrossSquare

Related effects

• DitherOrdered dithering: Bayer and blue-noise threshold masks quantised to real machine palettes — Game Boy, PICO-8, CGA, EGA, NES, C64, ZX Spectrum and more.
• RisographSpot-ink riso printing: luminance separated into two or three inks, each screened at its own angle with mottled grain and multiplied over tinted paper — mis-registration and all.
• Error Diffusion DitheringError-diffusion dithering with the real algorithms — Floyd–Steinberg, Atkinson, Sierra, Stucki, Jarvis–Judice–Ninke, Burkes, Ostromoukhov's variable-coefficient kernel and a Hilbert-curve Riemersma — plus three of our own that treat the kernel itself as the instrument, run as true sequential propagation, not a lookup mask.

It’s one of the free effects — open the app and it’s there, no signup. Open V3KTR · all the FX · how it works