Opening a pdf in photoshop, rasterization settings?

[WGC66]

Hello,

When I open a pdf created outside photoshop, (this is a technical image created on engineering software) I get the "open" dialog box with various settings. Under "Image size / Resolution" the default setting always appears to be 300ppi. Is this an indication that the file was actually created with 300 ppi resolution, or is this just a default setting?

I know I can adjust this and "add" resolution to the image, but what I'm trying to determine is the native resolution in the file to see if its suitable for use at a certain output. I've always just opened files in Photoshop and selected Image size to see if the files resolution was appropriate for use. Is this method incorrect?

Should I be checking this somewhere else as a rule? Bridge? I've selected the file in Bridge, I can see a dimension but cannot find the resolution.

Can anyone shed some light on this issue?, it makes me second guess how I've been evaluating files for resolution.

[Alec Molloy]

PDF files don't technically have a resolution as they are vector documents. Any sort of ppi associated with PDFs would have to do with their images if you resampled them (such as when you export an interactive PDF from InDesign).

Photoshop will by default import PDFs at 300dpi. If you want to know what the resolution the images are, you can use Acrobat's Object Inspector to find out what the resolution of images are:

As there is no document-level ppi this is probably the best way to get an accurate reading on the resolution of your PDF short of eyeballing it when you import it into Photoshop.

This video explains how to use the document inpsector in Acrobat:

If this doesn't answer your question, just let me know.

[WGC66]

Thank you Alec.

Does this method work for non pdf files as well? (raster based images like jpegs, tiff's etc?)

In my industry, (tradeshow / large format graphics) we receive rasterized pdfs as well as jpeg and tiffs on a regular basis from ad agencies or graphic designers. We always need to inspect them and determine if they are of proper resolution for large format output.

[Alec Molloy]

Acrobat is only able to work with PDF files. You could convert a jpeg or tiff into a PDF using Acrobat, but I personally would either do a little math to determine if it is print-quality or drop it into InDesign at the size it will need to print and see if it works.

If you have InDesign installed you can use that program to do your layout using the raster images and check their effective ppi using the links panel:

Using InDesign might make most sense for you as you can do the layout for raster images here, and for PDF documents that clients have prepared you could use Acrobat.

The advantages of using both like this are that they have very powerful industry-standard prepress features. These prepress features can do most of your work for you by checking for low resolution images, colors out of gamut, missing links, type embedding problems etc.

More on prepress in InDesign here, this is for CS3, but the process is essentially the same in CS6: (I would skip through to 2:00)

And prepress in Acrobat XI:

[MMI]

Late reply for those looking up the same question, as i was.

When importing pdfs into photoshop you can also select "Images" instead of "Pages" at the top left of the dialog box. This opens the images at their native size, enabling you to check resolution.