How Sure Are You?

A colour on a screen is a promise; a drawdown under a booth is evidence. Between them are four steps, each answering one more question about what you are looking at. This is what each one settles, and what it still cannot see.

Each step keeps everything the one before it settled and removes one more assumption. Steps 1 to 3 are the screen path; step 4 is the print path, and the two are worth running in parallel rather than in sequence. Nothing here changes the colour: the code, the spectrum and the aim are the same throughout.

1 · On screen, unverified

The Ink Drawdown page draws the colour from the library’s own measurement, on the paper you choose, under the light you choose. What it cannot know is your display, so the state line says so: Display not checked.

That is enough for real work. Is this the right family? Does it sit well against the paper? Which variant of the Variator looks like the drawdown in your hand? One condition: the colour has to be inside what the screen can show. A saturated ink on an sRGB display is clipped, and clipped means you are looking at a different colour.

2 · The display measured

With the Instruments Bridge and an X-Rite i1Display on the glass, the page stops trusting the profile. It reads the white, the paper and every patch of the picture, corrects each one, and reports what it could not reach — see Checking Your Display.

This is the step that changes the conversation. A verified screen is no longer an opinion; the numbers under it are measured on your monitor, in your office, this afternoon.

3 · The light measured too

The next two steps leave this site. ChromaChecker’s CC Capture is a desktop application with its own Ink Drawdown, and it adds what a browser cannot reach: the light. Its Lighting Inspector measures the lamp you judge under — spectrum, colour temperature, colour rendering, illuminance — and checks it against the monitor, because a booth at 2000 lux beside a screen at 80 cd/m² is two different worlds pretending to be one.

Now both halves of the comparison are known: what the screen emits and what the booth throws. The remaining unknown is the one that matters most, and it is not on the desk.

4 · The ink itself

Everything above is still a simulation of an ink nobody has mixed yet. The last step is physical, and needs an instrument and software of its own: the ink is formulated for the production substrate, drawn down on it, and measured — the step every supplier should be taking anyway, and where CxF/X-4 belongs.

Two things become visible only here.

The production adaptation. The ink that reaches the press is not the ink that matched on paper: the pigment load changes for the substrate, the varnish, the process. A second drawdown on the production sample tells you what that did to the colour, and the concentration ladder tells you which way it will drift when the film runs thick or thin.

The observer metamerism index. A production ink usually carries different pigments from the reference. Two spectra that agree under one light and one observer will part company under another — and people differ too. The index puts a number on that risk, computed from the two spectra, which is possible only because both are measured. Nothing on a screen can tell you this: see Observer Metamerism.

Two paths, run in parallel

Screen and print are not stages of one road. They are two independent chains of evidence about the same colour, and the honest way to work is to keep both running and measure both. Where they agree, the colour is as sure as it gets; where they disagree, you have found a mistake before it cost anything.

The screen path

Ink Drawdown and soft proofing settle a great deal: the colour against its substrate, the tolerance around it, the variants either side of the aim. With the display measured, that judgement carries a number. It is the cheapest step in the chain and it happens before anyone mixes anything.

The print path

What a controlled print means depends on how the job will be made.

Process printing — CMYK or nCLR. Where the colour is built from process inks, ChromaChecker’s LUT technology for colour palettes reaches very high precision on any substrate and with any finishing, because it iterates: print, measure, correct, print again. The correction belongs to that substrate and that varnish or laminate, which is exactly what a generic profile cannot be.

A separated spot colour. A spot ink is mixed, not built, so it has to be printed as itself. Proofing presses such as RK Print, and others of that kind, give a controlled print of the ink on the production substrate. Characterised at the full CxF/X-4 level it carries the colour, its tints and the ink’s opacity, which nothing on a screen and no process build can tell you.

The standard’s own names are clearer than the letters: CxF/X-4 Full Characterisation, X-4a Single Background, X-4b Single Patch. Only the full level prints a second set of tints over a black region — same tint levels, on black no lighter than L* 20 — and only those patches make opacity measurable. X-4a describes colour and tints on one background; X-4b is the solid alone, a delivery check rather than a characterisation.

Which step do you need