Colour deviation: the one rule to keep first
Colour deviation compares the sheet with the signed sample. In ISO 12647-2 the common limit for the four process colours is ΔEab 5, and the version named in the contract is the one that counts. It is not the swing from one sheet to the next.
Colour deviation compares the sheet with the signed sample. In ISO 12647-2 the common limit for the four process colours is ΔEab 5, and the version named in the contract is the one that counts. It is not the swing from one sheet to the next.
What this rule covers
Do not treat ΔEab 5 as the swing allowed from sheet to sheet. Variation looks at another set of numbers, not this rule. Deviation is against the sample. Within a lot, variation is another matter: cyan, magenta and black commonly ΔEab 4, yellow commonly 5, hue commonly ΔH 3.
Check
| Item | Do this | Do not |
|---|---|---|
| Colour deviation | Colour deviation compares the sheet with the signed sample. In ISO 12647-2 the common limit for the four process colours is ΔEab 5, and the version named in the contract is the one that counts. It is not the swing from one sheet to the next. | Writing only a feeling |
| The common mistake | Do not treat ΔEab 5 as the swing allowed from sheet to sheet. Variation looks at another set of numbers, not this rule. | Going along with the wrong reading |
| What to leave | The report must state ΔEab, which signed sample it is against, the M condition, the geometry and the backing. If one is missing, do not call it a pass. | Leaving only the word pass |
Do these three first
- First see whether the contract says deviation or variation.
- Write down the geometry, the M condition and the backing.
- Only compare two readings taken under the same conditions.
