Question: Hi Cameron, I’m wrapping up a transit map project that I’ll likely print professionally. I was all set to send the printer a PDF until I happened to catch one of your tweets that mentioned using a high-resolution JPEG instead. I’m wondering if you could share your recommended practices for exporting from Illustrator to print-ready JPEG in terms of resolution, color profiles, and the like. The last thing any of us wants is to shell out $$$ for printing only to wind up with crappy results! Thanks!

Answer: Print requirements vary from print shop to print shop, so my best advice is to talk to the people that you’ve chosen and discuss these things with them. Communication is key to a good print job!

A PDF is far more likely to be acceptable to someone who is printing four-colour process through a proper RIP engine than to someone printing on a high-end inkjet printer. Inkjets often lack a RIP, so they can’t process Postscript or PDF files properly, ending up with output like this. (Image courtesy of Oran Viriyincy/Twitter)

What’s happening here is that the printer can’t use the Postscript/PDF, so it fakes it (badly) by printing the lower-resolution raster preview instead. Ugly, and completely unacceptable.

I used to send vector PDFs to my inkjet print guy until he told me that he just opened them in Photoshop and exported them as flattened PSDs to print. So now I do it myself, just as reassurance that everything is going to look exactly the way I want it to. For inkjet printing, 300dpi RGB files in the sRGB colour space work perfectly for me (any RGB colour space has a larger gamut – or range of colours – than CMYK). Your printer should have a colour profile that matches the paper they’re printing on to ensure colour fidelity. 

Exporting is easy enough. Make your final vector PDF or EPS from Illustrator, and simply open that file in Photoshop. Choose the required print dimensions, resolution (300dpi) and colour space (RGB) in the dialog box… let it process… check everything looks as it should, flatten the image and save! You could also export as a TIF or PSD via Illustrator’s File > Export menu item, but I’ve personally found that this can misinterpret objects on occasion, making it too unreliable for me to trust.

I’d recommend PSD or TIF over JPG as your final file format as they are lossless formats: even a high-quality JPG discards some information to get those small file sizes.

And definitely get a proof print before committing to a print run – if the quality is unacceptable, work out why or find a new print shop if they can’t help.