Printing a multi-layer process means combining two, three, or four successive prints on the same paper. Each layer brings its chromatic contribution (a channel in CMYK Aquaprint), tonal contribution (a pigmented transfer in carbon), or opacity contribution (a gum pass, a screen printing film). The final result is the sum of the stacked layers.
The challenge with these multi-layer processes is alignment. If you shift the second layer by a millimeter relative to the first, your final print has a visible defect — doubled edges, a colored edge cast, blurred tonal definition. By eye, with no reference, it's almost impossible to lay a transparency in the right place on an already-printed paper.
Registration solves this. On the Effects sheet, turn on Registration (crosshair icon): Calibration Flow automatically adds marks to the corners and margin of each negative.
#What you see
- A target in each corner: a ring and 8 spokes (4 diameters) crossing at the center. It's this crossing point — not the ring's outline — that gives you your precision reference.
- An orientation key in the top-right corner: the same target, but without the spokes — just the ring and a solid dot at the center. It makes that corner unique: if you find it in the bottom-left instead of the top-right, the sheet has been rotated a half-turn or flipped (front/back).
- Black-and-white density wedges (a gradient from 0 to 100%), placed in the margin band between the targets — never on the image. In color, one wedge per ink, marked by its letter: four at the bottom, and in Full Gamut up to three more at the top. The app prints the French initials, whatever the interface language: C, M, J (yellow), N (black), then O, Ve, Vi (orange, green, violet). In monochrome, a single large wedge at the bottom.
- Two labels in the side margins: on the left, written vertically, the name of the chosen curve; on the right, the rendering style — “Continu” (continuous tone) or “Trame” (halftone) followed by the resolution and the line screen. The app writes these two words in French. The negative says for itself how it was made.
#Why the target is printed in reserve
The target isn't a simple thin outline: it's a solid disc with the ring and the spokes cut out of it. On the print, the disc carries the ink and the ring and spokes stay paper white. A thin-line reticle would print as a nearly invisible thread of pigment — especially in yellow, often the first pass — impossible to register against the next layer. In reserve, the outline stays crisp regardless of the ink.
On the black-background negative in the screenshot at the top of the page, you see the reverse: a clear disc, which will let the light through, with the ring and spokes in black.
#How to register in practice
- Print your first plate and fix it on the paper.
- Lay the next plate's transparency on top. Line up each target's spoke-crossing with the one already printed — on the targets, not on the image.
- Check the top-right corner: the key already printed and the key on the new transparency must land exactly on top of each other. If they diverge, your sheet is rotated or flipped — fix it before exposing.
- Repeat for each subsequent layer.
#The wedges: a print check, not just registration
On a separation plate (a single ink), only that channel's wedge is drawn, at its own slot, with its own letter — so on the stacked print, each wedge lands exactly in its place without mixing with the other layers' wedges.
When you apply a calibration curve, the wedge gets exactly the same transformation as the image (curve and negative). It then becomes a control target: after printing, you can scan it or read it with a densitometer to check that this layer was properly exposed, without waiting to judge the result on the image itself.
#Forced wide margin and wedge row
Turning on Registration automatically locks in a wide margin — the margin buttons are locked while the option is active. That's intentional: the wedge band needs room without encroaching on the image.
A related option appears only when Registration is on: Step-wedge row, a row of grey wedges along the top of the sheet. It lets you test several exposure times from a single negative instead of printing several.
#Why it matters
For CMYK four-color Aquaprint. Four successive layers — Cyan, Magenta, Yellow, Black. With each new layer, you lay the next transparency on the paper where the previous layers are already fixed. Without a reference, you align by eye on the image itself, which is imprecise. With the targets, you align on the spoke-crossing, and you gain precision — commonly on the order of half a millimeter in careful work.
For color carbon. Like CMYK four-color Aquaprint, Calibration Flow's color mode generates 4 channels (Cyan, Magenta, Yellow, Black) — that's four pigmented-gelatin transfers. The targets and their crossings remain the most realistic way to align these layers; Vision Picturale doesn't document a specific precision figure to cite for this process.
For multi-pass gum bichromate. If you make a Monochrome Aquaprint in two or three successive passes (to build up the pigment), the targets let you lay the second and third pass exactly on the first. Without that, your density builds up unevenly and you get blotches.
For multi-ink screen printing. When you separate an image into 2, 3, or 4 film positives (Sanguine or four-color), each film is exposed and printed separately on the screen. The same targets help you register the films against each other before exposure — see Making a film positive for screen printing.
Also useful on monochrome processes — for checking, not registering. Even on a single-layer process, you can leave Registration on just for the density wedge in the margin: it works as an exposure-control target on scan (see above), not as registration between layers, since there's only one.
#When the registration targets serve no purpose
For single-layer processes — cyanotype, platinotype, palladium, Van Dyke, bromoil, gumoil, resinotype — there's nothing to align between two transparencies. The four targets bring you nothing for registration (the margin wedge can still be useful — see above).
For target prints, the option doesn't make sense: the calibration target is already its own reference.
For images with no margin: this case no longer arises with Registration on, since the option itself locks in a wide margin.
#Not to be confused with the Color Venn
The Color Venn is a different tool: a reference target made of three overlapping Cyan/Magenta/Yellow circles, generated on the site, that you compare by eye to see how your pigments mix — no scan-based measurement. It has nothing to do with this page's registration targets — one helps you judge your pigment mixes, the other physically stacks your transparencies.
#Worth remembering
| Item | Value |
|---|---|
| Position | Four corners of the negative (target), top-right corner (key) |
| Target shape | Ring + 8 spokes crossing at the center, in reserve (paper white) on a solid disc |
| Orientation key | Ring + solid dot, no spokes — top-right corner only |
| Density wedges | Margin band, B&W gradient 0→100%; one per ink in color (channel letter), one large wedge in mono |
| Margin | Locked to wide as soon as Registration is on |
| Related option | Step-wedge row (one negative, several exposure times) |
| Relevant processes | CMYK Aquaprint, color carbon, multi-pass gum, color screen printing; control wedge also useful in mono |
#The test
Generate two negatives (for example two CMYK Aquaprint plates) from the same image, with Registration on. Print both on separate transparencies. Stack them on a light table, focusing on the targets rather than the image: one corner's spoke-crossing should overlap exactly with the one already printed — gently slide the second one until it lands right. Then check that the top-right key also lands on its counterpart: that's the proof the sheet is neither rotated nor flipped. If all four corners and the key line up, registration is validated.