PDF/A error: missing OutputIntent
The document uses colour that only has a defined meaning relative to some output device, but does not say which device — that is what an OutputIntent with an embedded ICC destination profile provides. Fix it by adding an OutputIntent, or by converting every colour to a device-independent space.
The Colour check group covers 6.2.2 OutputIntent, 6.2.3.x device colours, 6.2.9–10. The exact sub-clause is reported on the issue itself when the validator raises it.
What causes it
- The document was produced by a writer with no notion of colour management, so DeviceRGB or DeviceCMYK values were emitted with no profile attached.
- An OutputIntent was present in the source but stripped by a later processing step, such as an optimiser or a merge.
- Pages were merged from several documents and only some of them carried an OutputIntent.
How to fix it
- Add an OutputIntent with an embedded ICC profile matching the intended output condition — sRGB for screen-oriented documents, a CMYK press profile for print.
- Convert the document: gopdfrab injects an OutputIntent as part of PDF/A conversion.
- Alternatively, replace device colour with an ICCBased or CalRGB/CalGray colour space so no output intent is needed for those objects.
Frequently asked
What is an OutputIntent, exactly?
A dictionary in the document catalog naming the output condition the document was prepared for, with an ICC profile embedded in the file. It is what makes "50% cyan" mean a specific colour rather than a device instruction.
Can a document have more than one?
PDF/A-1 requires that all OutputIntents in a file specify the same destination profile. In practice, one is what you want.
Does adding an OutputIntent change how the document looks?
It should not change the colour values already in the file, but it does fix their interpretation. Choosing a profile that does not match how the document was actually authored can change how it renders — pick the one matching the intended output condition.