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About This Site

A small set of colour conversion tools built around one idea: show the working, and be honest about where the maths stops being useful.

Before you publish

Replace this section with a real name, a real photograph and a genuine account of your print or design background. Google weighs first-hand expertise heavily in technical niches, and a site giving press advice from an anonymous author will struggle against one that does not. This is the single highest-value edit on the whole site.

Why this site exists #

There is no shortage of colour converters. Most of them give you a number and nothing else, which is fine until the number does not do what you expected — and with print colour, it very often does not.

So every converter here shows the formula it used, works through one example by hand, and says plainly what that formula gets wrong. The RGB to CMYK arithmetic, for instance, quietly assumes that ink behaves like a perfect filter. It does not, and knowing that is more useful than another decimal place.

How the conversions are calculated #

All of the conversion functions were written from scratch for this site, from the published mathematical relationships between the colour models. No third-party colour library is used. The formulas are printed on the relevant converter pages so you can check the working or implement it yourself.

Everything runs in your browser. No colour you enter is transmitted to us, logged, or stored anywhere.

What this site does not do #

  • It does not replace a colour-managed workflow. If you know which press is running your job, your design software with the correct profile will always beat generic arithmetic.
  • It does not replace a physical proof. Nothing on a screen can.
  • It does not publish licensed colour data. Proprietary colour systems belong to the companies that maintain them, and we do not reproduce their libraries.

Corrections #

If you find an error in a formula, a worked example or a table, email contact@hex-cmyk.com. Corrections get made and the review date on the page gets updated.