Prepress and commercial print / PDF/X-3
PDF/X-3: managed colour instead of CMYK only
The same handover discipline as X-1a with one rule relaxed: device independent colour is allowed, so ICC tagged RGB and Lab content can stay in the file and be converted by the printer's own colour management.
Where this API stands
This API does not produce this standard, and there is no option that would. What follows is what the requirement actually is and where a rendered document stands against it. This API produces neither ICC tagged RGB nor CMYK. Colour goes into the file as device RGB with no profile attached, which is the one colour category X-3 still refuses, so a rendered file fails preflight for the same reason it fails X-1a even though the standard is more permissive. There is no colour management option to set. What you control is whether the document uses transparency, which X-3 forbids just as firmly as X-1a does, and whether your colour values were chosen with printing in mind at all.
What the standard requires
The requirements as a checker enforces them, rather than as a procurement document paraphrases them. A file satisfies all of these or it satisfies none of them.
- Colour that is either CMYK, a named spot, or device independent and properly tagged with an ICC profile. Untagged RGB is still not permitted.
- No live transparency, exactly as in X-1a, since X-3 is built on the same PDF generation.
- All fonts embedded, one output intent with an embedded profile, and a TrimBox or ArtBox on every page.
- The Trapped entry present and set to True or False.
- An expectation that the printer will do the final conversion, which means their profile decides the result rather than yours.
- The output intent chosen to describe the actual press condition, because that is the target the printer converts towards.
Who asks for this
Printers with a colour managed workflow, and clients who want one file to work for both print and screen. It is the standard to reach for when the artwork contains photography that would suffer from an early conversion, since a late conversion using the press profile retains more of the original gamut than a generic one applied by whoever exported the file.
What to do about it
Convert on the finished file and decide at that point whether you are tagging or converting. A preflight tool can assign a source profile to the untagged RGB and leave it device independent for the printer, which is the X-3 way, or convert everything to the press CMYK, which produces an X-1a file. Ask the printer which they prefer, because a shop with no colour management will get worse results from a tagged file than from one you converted yourself.
How to check a file rather than assume
Acrobat preflight or a callas profile targeting PDF/X-3, which reports untagged colour objects individually. Check the output intent as well as the pass or fail: an X-3 file with an intent describing the wrong press condition is conformant and will still print wrong, and no validator will tell you that.
The mistake people make here
Choosing X-3 to avoid making a colour decision. Deferring the conversion to the printer only helps if the printer actually runs colour management, and plenty do not. Leaving the decision to a shop that then applies a default conversion is worse than converting yourself against their stated condition, because at least you could have proofed it.
Frequently asked
Does this API produce PDF/X-3?
Not produced by this API. This API produces neither ICC tagged RGB nor CMYK. Colour goes into the file as device RGB with no profile attached, which is the one colour category X-3 still refuses, so a rendered file fails preflight for the same reason it fails X-1a even though the standard is more permissive. There is no colour management option to set. What you control is whether the document uses transparency, which X-3 forbids just as firmly as X-1a does, and whether your colour values were chosen with printing in mind at all.
Can I turn on the pdf_a option and be done?
No. The option writes an XMP packet declaring PDF/A-1b into the document catalogue, and the render response comes back carrying a warning that says in as many words that this is best-effort and that full conformance requires tagged structure and an embedded ICC profile. It is a claim written into the file, not a certificate earned by it, and a validator checks the claim against the bytes. Read the warning array in the response rather than taking the absence of an error as a pass.
Should I convert before rendering or after?
After, always. A conformance converter rewrites colour, embeds profiles, sets boxes and stamps metadata on a finished PDF. Trying to satisfy a conformance target from the source side means guessing at what the converter would have done, and the guesses that go wrong are expensive: flattening transparency you did not need to flatten changes what the page looks like.
Standards this one is confused with
The neighbours that matter are the ones people mistake for this, not the ones that sort next to it.
PDF/X-1a: the CMYK-only handover format for commercial print
The blind exchange standard for offset printing: everything is CMYK or a named spot colour, nothing is transparent, and the file carries enough information that the printer never has to ask you a question.
PDF/X-4: live transparency in a print handover file
The current print exchange standard, based on PDF 1.6, which keeps transparency and layers live in the file and lets the printer's own engine flatten them at the last possible moment.
Output intent: the ICC profile an archival PDF has to carry
A dictionary in the document catalogue holding an embedded colour profile, which is what turns an otherwise meaningless triple of numbers into a colour a future reader can reproduce.
CMYK and spot colour in a PDF, and why CSS cannot reach them
Print uses inks, the web uses light, and there is no CSS syntax that expresses either a CMYK ink mixture or a named separation, so the gap has to be closed somewhere other than the stylesheet.
Bleed, trim and media boxes in a PDF built for printing
A printed page has at least three rectangles: the sheet, the finished size after cutting, and the slightly larger area artwork must fill so that a cut a millimetre off does not leave a white sliver.
Every standard, with what this API does about it
The full list, grouped by what the requirement is for, each marked with how far this API gets.
What this API actually does
One page per option and endpoint that exists, with nothing that does not.
Conformance is decided after a file exists. Render the document, then check it, then convert only what the checker actually flags.