I am trying to print a pdf file in CMYK format with vector artwork that also contains a raster image but the vector artwork color does not print accurately. I have tried flattening transparency and converting colors to CMYK within the document but no luck there. Is it possible to achieve the right colors with this combination?
It is very common to have rendering problems when dealing with CMYK and transparency effects, especially if the document also uses spot swatches. There are a few things you can try. First, if possible, set any spot colors to print as process. Then try to create a PDF/X-1 standard PDF. This can have unexpected results if the spot colors are not converted to regular swatches or set to output as process first. If all else fails, and if you have Photoshop, rasterize the document at 300ppi at 100% print size (for hand-held documents) or at 150ppi for large format pieces. If you are working with a multiple-page document, you just need to do this the problematic pages. For best results, rasterize in RGB, then convert that to CMYK.
[Edit]: Should have said: For best results (if the source is in mixed gamut) rasterize in RGB, then convert to CMYK.