From file to four-color negative

This guide is for four-color printing — Aquaprint color, carbon color, any process that overlays four inks (Cyan, Magenta, Yellow, Black) to reconstruct a color image. It assumes you already have a calibration curve for your process. If you don't, a first calibration comes before this path, not after.

This path does not read your image as an aesthetic decision (that's the job of reading and rendering, a different path). It produces a technical file: four negatives that, layered in the right order and aligned to one tenth of a millimeter, yield your color print.

#What you see

Step 1 — You apply your calibration curve. Your curve corrects your process's tonal response — see Reading the correction curve. Without a curve, the separation that follows will reproduce the uncorrected flaws of your chemistry on each of the four layers.

Step 2 — You choose your test chart. Before separating a real image, a test chart validates that your chain works. The chart tests each layer in isolation — it's easier to diagnose than a full photograph if something goes wrong.

Step 3 — You separate your image into four negatives. Once the chart is validated, move to your real image. CMYK separation splits your file into four negatives — one per ink — each destined for a separate exposure on a different layer of chemistry.

Step 4 — You align the layers. Four negatives exposed separately must overlap exactly at the print, or the final color image will be blurry or doubled. Registration marks mark each negative so you can re-register them to the print.

Step 5 — You adjust the export. Once your four negatives are ready, export options set the format and settings of the final file you'll print to film.

#Why it matters

To avoid discovering a registration error after four exposures. Four-color printing requires four separate chemical passes — an error caught after the fourth is an entire print to remake. Validating each step (chart, separation, alignment) before moving to the next limits the risk of discovering the problem too late.

To understand why the curve comes first. A curve applied after separation corrects nothing coherent — each layer has its own chemical response, and the curve must apply before the image is split into four.

To know where this path stops. This guide produces negatives ready for exposure. It does not cover exposure itself, washing, or aesthetic judgment of the final render — that remains your chemical craft and your eye.

#When to skip steps

You're printing in monochrome. This path is specific to four-color printing. In black and white, a single negative is enough — no need to go through CMYK separation.

Your curve and chart are already validated for this series. If you've already calibrated and tested your chain recently on the same paper and chemistry, you can skip straight to step 3 for a new image in the same series.

You're experimenting in Full Gamut (5 to 7 inks). If you go beyond classic four-color (adding Orange, Green, Violet), this four-layer path doesn't cover extended inks — the principle remains the same, but the settings differ.

#Worth remembering

#The test

Take an image already corrected with your calibration curve. Follow the five steps in order without skipping any. At the end, you should have four distinct negative files, each with its registration marks visible. Overlay them on screen (or print them on film and hold them up to the light together) — the registration marks must align exactly. If they don't align on screen, the problem is in the export, not in the exposure to come.