How close does a contract proof have to be, and what tolerances apply?

What a contract proof is for

A contract proof is a print — usually inkjet — made to simulate a standard printing condition closely enough that the printer and customer can agree on it as the colour reference before the job runs. Its value lies in verification: every proof carries a control strip, such as the Fogra Media Wedge, whose patches are measured and compared with the published aims for the simulated condition, and the result is printed on a label. An unlabelled proof from a desktop printer, however good it looks, is a 'validation print' at best and has no agreed tolerance.

The 2016 switch to CIEDE2000

Earlier editions of ISO 12647-7 expressed tolerances as ΔE*ab, the straight-line CIELAB distance. The 2016 third edition requires every colour difference to be reported as CIEDE2000 instead, and warns that the two do not convert simply: some proofs that passed the 2013 edition will fail the 2016 one and vice versa. The reason is perceptual: ΔE*ab overstates differences in saturated colours and understates some near-neutral ones, so a fixed ΔE*ab tolerance was simultaneously too strict for yellow and too lax for greys. CIEDE2000 weights lightness, chroma and hue to follow visual judgements more closely.

The tolerances, and what they cover

The table summarises the headline requirements. Two details matter in practice. First, grey balance is checked separately as a hue difference on a CMY overprint scale, because greys drifting pink or green are what viewers notice first. Second, the standard itself says tolerances below 2.5 ΔE00 are not practical to specify because different instrument models disagree by about that much, and recommends halving the tolerances when the same instrument measures both proof and reference. It also caps variation across one proof sheet and day-to-day repeatability, so a proof cannot pass on a lucky patch.

From proof to press sheet

The proof represents the aims; the press run has its own tolerances around the same aims in ISO 12647-2 for offset, and the press operator matches the proof visually and by measurement in a D50 viewing booth. Surface finishing — varnish, laminate, UV coating — changes colour noticeably, so a proof of an unfinished condition will not match a laminated product; the standard says finished products need their own simulation. When press and proof disagree, measuring both against the aims shows which one is off, which is the whole reason for printing the control strip.

The data

What goes wrong, and what to do

What the evidence says

Each statement is labelled by kind — established fact, a standard’s requirement, observed market data, a convention, or Colourwise’s own interpretation or analysis — with the strength of the evidence behind it.

• StandardStrong evidence

  ISO 12647-7:2016 requires colour differences to be reported as CIEDE2000 (ΔE00) rather than the ΔE*ab used in earlier editions, and notes there is no simple correlation between the two.

  Source: ISO 12647-7:2016 … — Part 7: Proofing processes working directly from digital data

• StandardStrong evidence

  Under ISO 12647-7:2016 the proof substrate must match the simulated production substrate within 3.0 ΔE00, and the process colour solids must match their aims within 3.0 ΔE00 with a CMY hue difference of no more than 2.5.

  Source: ISO 12647-7:2016 … — Part 7: Proofing processes working directly from digital data

• StandardStrong evidence

  For the control strip, ISO 12647-7:2016 allows a maximum of 5.0 ΔE00 and an average of 2.5 ΔE00, a maximum of 2.5 ΔE00 for spot-colour solids, and states that tolerances below 2.5 ΔE00 are impractical because of poor agreement between instrument models.

  Source: ISO 12647-7:2016 … — Part 7: Proofing processes working directly from digital data

• StandardStrong evidence

  Across nine locations on one proof, ISO 12647-7:2016 limits the standard deviation of L*, a* and b* to under 0.5 each and the difference from the average to 2.0 ΔE00.

  Source: ISO 12647-7:2016 … — Part 7: Proofing processes working directly from digital data

Related questions

What is the Fogra Media Wedge?

A standard strip of CMYK patches printed on every contract proof. Measuring it and comparing with the simulated condition's data is how a proof is shown to meet ISO 12647-7.

Why is the spot-colour tolerance tighter than the average for process patches?

A spot colour is a single named target that viewers compare directly with a reference swatch, so it is held to 2.5 ΔE00 on its own rather than averaged with other patches.

Does a certified proof guarantee the press sheet will match?

It guarantees the proof represents the standard condition within tolerance. The press must also run to that condition within its own tolerances; the two tolerances add, so small visible differences remain possible.

Related topics

Go further

Sources

• ISO 12647-7:2016 … — Part 7: Proofing processes working directly from digital data — ISO (TC 130) (Official standard or government)

Reviewed 29 September 2026. Colourwise summarises its sources in its own words and does not reproduce standards text or proprietary colour data. Spotted an error? Tell us.