PDF artwork for large posters - filesize issues?

Question

I am designing large posters for print...A2 size and bigger. I create my photoshop file as 594 x 420 mm, drag a jpeg image which 7.6MB onto the canvas, enlarge it to fit canvas, then drop a logo onto it. I save as a PDF for print, which then saves to be over 200MB, which is huge.

How do I design large images for print? If I design on a smaller canvas at 300DPI, can the printers then enlarge it without effecting the quality?

Or what else can I do? Most things I am designing (a4 print ad's) end up being 50-odd MB's, is it because of the images I am using or what?

Answer 1

If you're designing for print, you shouldn't be enlarging JPEGs anywhere. It defeats the purpose of having a high resolution image if you're just stretching out lower-resolution images and saving. Also, 200MB isn't that big for a large poster. All that extra pixel data has to go somewhere. I've worked with CD layouts that have been much bigger than that.

If you need to reduce the size for transferring to the printer, then you can flatten as many raster layers (flattening vector layers won't reduce file size much in most cases and could potentially increase file size) as possible.

Other than that, check that you're saving your PDFs with ZIP compression for images and you're not including unused/hidden layers. Artwork that is suitable for vector graphics should also be embedded as such.

Answer 2

You are enlarging an image in photoshop. Photoshop is a raster based software program. So if you bring in a 10px square image and enlarge it to 100px in Photoshop, it's gone from a 100 pixel image to a 10000 pixel image. Naturally, this will be a much larger file size.

However, those pixels are 'made up' pixels meaning they weren't there to begin with, so for most images, enlarging within photoshop won't really gain you any image quality to speak of when you go to print.

As such, I'd suggest that Photoshop is simply the wrong software to be using. Instead, use something like Adobe Illustrator or InDesign.

Import your image and scale it in that software. That software won't add pixels. Your 10px square image will still contain 10px of data--it's just that the pixels will be bigger now.

Now you can add your logo, export as PDF.

Answer 3

The first and most important thing you should do to reduce the size of your PDF is uncheck "Preserve Photoshop Editing Capabilities". If you leave that checked, Photoshop will save a complete copy of the PSD inside the PDF, invisible to the printer's RIP but making the file itself massive. (An "Illustrator PDF" is the same way -- a complete Illustrator file hidden inside the PDF wrapper.)

An alternative is to select a PDF/X standard in the PDF dialog, which automatically doesn't save an editable PSD.

The second thing you might do is optimize the PDF, but I think the above is the answer you're looking for.

All of the things DA01 and Lèse majesté said are excellent advice, too, however.