My company recently sent a PDF file that had been prepared by our graphic designer to a commercial printer for a large poster-size "pullup" to use at a trade show. The contents include a fair amount of detail - thin, straight lines, sharp edges, etc.
The proofs we got back show extensive aliasing ( AKA jaggies AKA staircasing) on the edges and lines, that are simply not in the original PDF file at any scale. I thought that the printer did something wrong so I opened the PDF in Photoshop took a cropped sample so it would be the same size as the actual commercial print, and printed it on our office printer at the highest quality settings, and it had the same jaggies as the commercial print! These jaggies are NOT in the cropped image at any scale.
I then took the JPEG image that the graphic designer used to make the PDF and printed that at the same scale as the others. No jaggies.
I then took the PDF file and converted it to JPEG in Photoshop and the converted file had jaggies visible on the screen that didn't exist in the original PDF file. So, somehow, when the PDF file is converted to something else - printer format or JPEG it's getting these terrible artifacts.
What's causing this and how do I fix it? Thanks in advance!
PS - When I load the PDF file into Photoshop it spends a long time rasterizing it first. I assume this means that PDF is not a natively bitmap format. Could that be the problem? Should our graphic designer use some other format to submit to a commercial printer?
Is there a setting when creating the pdf file to optimize it for screen or print ? That could be the problem.
Or maybe printing software is paying attention to a silly default setting of 72 ppi within the pdf file. Adobe likes defaulting to 72 ppi but nobody really uses 72 ppi these days.
