You must have an original ,unfaded swatch of paint. Usually the inner part of a door.
When you have it scanned, they will have a color and formula to give you in the
line of paint THEY carry. This can be translated to a brand you might have a preference
for. They run from cheap to very expensive. NEVER go cheap. Sikkens, SpiesHecker,Glasserit.
these are premium paints and you will get what you paid for.
Mad dog