Created attachment 6842 [details]
PDF file with a simple object in an ICCBased space.

PDF files which contain valid ICCBased colour spaces produce PDF files where 
the colours have been converted to the Alternate space instead of preserving
the ICCBased colour space.

This is due to the new ICC workflow, and is caused because pdfwrite cannot differentiate between an ICCBased space which was in the original document, and one which has been manufactured for colours in a different original space.

As a result the ICCbased space is treated as the base space instead, leading to the loss of the original ICC colour space.