Rosette
A press proof that never dries: a folded sheet turns in the light, and every frame is separated into ink plates, screened at its own angle and printed back onto paper — set the screen angle a few degrees off and the whole sheet breaks into moiré.
Rosette
A sheet of paper is falling, slowly, in a photographer’s sweep. That is the whole subject — no object, no scene, just a rectangle of paper folding along five sine waves at once, lit warm from the upper left and cool from everywhere else. It is rendered in WebGL to an off-screen buffer at exactly the size of the trim area, and it is never shown to you.
What you see is the printed version of it. Every frame, the off-screen image is pulled apart into ink plates. Each plate takes its own reading of the colour — cyan where red is missing, magenta where green is, black where all three agree — turns that reading into a dot whose area matches the density, rotates the grid of dots to the angle that plate is screened at, shifts the whole thing by that plate’s registration error, and multiplies its ink onto the paper. Four plates, four angles, four errors, sixty times a second.
At the default screen angle of 15° the plates sit at 15, 75, 0 and 45 — the angles a process press has used for a century — and the dots settle into the rosette, the little flower of overlapping ink that is the reason colour printing works at all. Pull the angle down to four or five degrees and the rosette collapses: the grids beat against each other and enormous moiré bands swim across the sheet, slower than the sheet itself is moving. At 0° every plate prints on the same grid and the colour goes flat and dead. All three are real press failures, and all three are worth sitting in.
The margins are not decoration. The crop marks and the three registration targets are drawn once per plate, carrying the same offsets the image does, so when you open the register they split into two, three or four coloured ghosts exactly the way a bad sheet does under a loupe. The control strip in the bottom right is a real one — solid, 70, 40 and 20 per cent of every ink on the press, labelled with its plate letter — and the slug line reports what the press is actually set to.
| Control | Effect |
|---|---|
| Fold | Amplitude of the folds in the sheet; at zero it is flat and the tone goes smooth, at full it crumples and the shadows get deep enough to need black |
| Drift | How fast the sheet turns and the folds travel across it; at zero the sheet is held still and only the plates keep breathing |
| Ink set | Four-colour process · a three-colour riso in fluorescent pink, federal blue and yellow · a two-ink duotone · a single black plate |
| Dot | Round dots, square dots, or a line screen — a ruled screen makes the moiré at low angles far more violent |
| Ruling | Number of screen lines across the sheet: 10 is a pop-art enlargement where one dot is the size of a fingernail, 140 is close to continuous tone |
| Angle | The spread between the plates. 15° gives the textbook rosette, 3–7° gives moiré, 0° prints every plate on one grid |
| Register | How far the plates drift from the key plate, stated in millimetres on a 340 mm sheet. 0.4 mm is a sloppy sheet; 4 mm is a press being shut down |
| Ink | The tone curve applied to every plate before screening — the difference between a washed-out proof and one running far too wet |
| Pull a sheet | Writes the proof as it stands, margins and all, to a PNG |
The press stops while the sheet is scrolled out of view, and holds its motion if you have asked your system for reduced motion.