(Photoshop is not the primary tool for making PDFs – Adobe InDesign and Illustrator are more popular, but many people don’t have access to them, and certainly can’t devote the considerable time necessary to learn them. So you have to do your best in Photoshop. What I’m about to discuss will help a lot.)
If you’re using Photoshop to design an advertisement, or a flyer, or whatever, make sure you don’t flatten the layers before you save the PDF.
The reason is that it’s important to preserve text as vectors. Vectors are mathematical shapes which are infinitely re-sizable; as opposed to pixels which cause all sorts of problems when resizing, as we know.
Here, I’ve prepared a simple file, with a mottled grey background, some adjustment layers, some text, and an additional image clipped with a vector mask:
For this test, I saved the file twice.
- First, I saved the layered file as a PDF.
- Then, I flattened the layers and saved as another PDF.
Then I opened the two PDFs in Adobe Reader, and zoomed in to compare the results. Here’s a section of the PDF file saved from the layered image:
And here’s a section of the PDF saved from the flattened image:
We can see how much better the text and star mask look when the vectors are preserved. Those edges are still straight and true. Even when I zoomed in to over 1000%, there was no degradation. Like I said, vectors are mathematical shapes which are infinitely scalable.
When you flatten layers in a Photoshop file, vectors are committed to pixels. And pixels are suitable for images, but not great for text, as you can see. The PDF format is the only output format capable of containing both pixels and vectors, and it’s a good idea to utilise that.
Of course, what I’m telling you is common sense anyway. If you’ve gone to the trouble of preparing a complex design, you definitely want to keep it in layered form in case you need to adjust something later.
Another thing to mention: if you’re preparing a PDF to be printed, it’s quite likely that it needs to be in CMYK format. Make sure you find out as much information as you can about the requirements in this regard. CMYK is a tricky beast, and very easy to get wrong. Please read this article about CMYK.
Would you like to learn more?
Learn absolutely everything there is to know about PDFs in Photoshop with The Prepress Class.
If you have a question about this article, please feel free to post it in Ask Damien.