show correct colours for CMYK annotations
According to the PDF spec it's possible to create coloured annotations which are non-RGB. However, when you create i.e. a CMYK annotation, Acrobat takes the first three values and interprets them as RGB. I.e. [1 0 0 0] results in red instead of cyan, see attached example.
Interestingly, Preflight validates the document so somewhere in the company the knowledge is available.
The goal should be that annotations are displayed correctly independent of how many colour channels are there.
anonymous
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Boris Oriet commented
This is not a bug.
This depends on the PDF version. As far as I know, PDF up to at least 1.4 didn't allow anything else than 3 components in the /C entry of an annotation. So a CMYK PDF/A-1 document, for example, cannot have colored annotation borders. This has changed as per PDF 1.7 anyway, where annotation borders can be specified as other color arrays, hence four components for a DeviceCMYK color.
I know you are refering to LaTeX Hyperref. More than a bug in Adobe products, this is a weird behavior of the package. There are other ways (specifically an appearance dictionary) to decorate an annotation (even with a colored border) than using the /C entry (which originally was intended for display only).
Extract : PDF 1.4 specification, p. 491.
Hope this helps! Boris Oriet
