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I'm having some trouble creating a PDF with Photoshop.

The client wants the final file to be "a PDF at 300 dpi".

I have an image (3300 x 2550 pixels @ 300 dpi) in Photoshop. (11" x 8.5" canvas)

It seems that no matter which method or setting, my PDF is always saved at 72 dpi because the PDF ends up at 792 x 612 pixels every single time.

I'm using Photoshop CS2 on a Mac. I've tried a "save as PDF" from the file menu and I've also tried a "save as PDF" from the print dialog box.

I even saved it as a TIFF (3300 x 2550 @ 300 dpi) and opened in GraphicConvertor, then saved as a PDF. Same problem... the PDF is only 72 dpi (792 x 612 pixels).

So how can I get the final PDF size to be 3300 x 2550 pixels @ 300 dpi?

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Have you tried a different file/different machine? –  e100 Feb 8 '12 at 21:05
    
@e100: Yes, totally different 300 dpi file on totally different machine using PS CS3 also outputs a 72 dpi file. The latest version of Pixelmator software does the same thing. –  Sparky Feb 8 '12 at 21:11
    
Very odd........ –  e100 Feb 8 '12 at 21:20
    
@e100: I think I figured out what's actually happening and I'll post as an answer shortly. –  Sparky Feb 8 '12 at 21:30
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3 Answers 3

You figured it out. The dimensions you see in Bridge for the PDF are the output dimensions in points, not the image size in pixels.

This is a sometimes misleading side effect of the fact that PDF is (in theory) resolution-independent, much as an Illustrator or EPS document is, that the "dimensions" of the PDF shown in Bridge are the print dimensions, not the pixels. Raster information in the PDF is, of course, at a particular resolution determined at the time the PDF is created. It could be 100 ppi or 1200 ppi; the document dimensions would be the same.

A "300 dpi PDF" is a document that contains raster information sized to 300 ppi at the specified output dimensions.

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+1, Yes, exactly. Sadly, I knew all this... it just took all day to realize I was not looking at pixel dimensions in the "Get Info" box. Apple should really have it labeled better in there. "Get info" on the PSD shows "3300 x 2550"... again without any units. Being so used to seeing numbers representing pixels, I guess I just naturally expected those numbers to always represent pixels. –  Sparky Feb 8 '12 at 22:23
    
It's a 3300 x 2550 pixel file set to 300 dpi yielding a 11 x 8.5 canvas. So as long as those dimensions in Photoshop are what I want, the PDF should be adequate (provided there is no down-samplings setting), right? By "adequate", I'm expecting to be able to print to 11 x 8.5 inches with the equivalent of 300 "dots" per inch of paper. –  Sparky Feb 8 '12 at 22:38
    
note also that with multiple raster images set up on a page, if you export/distill the PDF without down-sampling (nor up-sampling), then each raster image can be stored with its own unique dpi. –  horatio Feb 8 '12 at 22:47
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I no longer have CS2, so don't know if you can do this, but it works in CS5.

Save the image as Photoshop PDF from the file menu, using the PDF X1a profile. That will save the file as a CMYK PDF, at 300 dpi.

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No dice. I have two versions of PDF/X-1a listed, one labeled :2001 and the other :2003. Both created the same PDF at 792 x 612 pixels @ 72 dpi. –  Sparky Feb 8 '12 at 20:41
    
Same result in Photoshop CS3. Also tried Pixelmator with no luck. –  Sparky Feb 8 '12 at 20:55
    
The compression settings for these profiles haven't been changed? –  e100 Feb 8 '12 at 21:03
    
@e100: I can't comment on what those profiles are supposed to do. All I can tell you is that they take a 300 dpi original and save it as a 72 dpi PDF. –  Sparky Feb 8 '12 at 21:13
    
I meant, on the "Save as Adobe PDF" dialog where you specify the profile, have you checked what the "compression" settings for the profiles are actually set to? For those profiles they are 300ppi by default, but they can be overridden. –  e100 Feb 8 '12 at 21:18
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up vote 0 down vote accepted

Original File: 3300 x 2550 pixels @ 300 dpi (11 x 8.5 inches)

Now I believe that my conclusions based on observations were incorrect.

1) In Mac OS X.4.11, "Get Info" on the PDF simply shows "792 x 612" without units. (In pixels, compared to my original, this would calculate to be 72 dpi).

2) In Mac OS X.6.8, "Get Info" on the PDF shows no dimensions. In the Preview App (Menu > Tools > Show Inspector), it shows 792 x 612 points and 11 x 8.5 inches. There is nothing about "dpi" here.

So this is why I posted the question here. It appeared as if all PDF were being converted to 72 dpi no matter how I saved them.


Then I opened the suspect PDF in Acrobat Pro.

Menu > File > Properties > Description tab shows a page size of 11 x 8.5 inches. Nothing else listed there regarding pixel or point size. Also, there is nothing there about dpi.

However, there is a button labeled "Additional Metadata". Under the item called "Camera Data 2", there it is: Pixel Dimension X: 3300, Y: 2550, Resolution X: 300, Y:300, and Resolution Unit: Inch.

So it appears that these PDF's are not 72 dpi after all.

Yes, I realize pixels are not the same as points. My confusion was caused by how the information is presented by the Mac OS (Get Info, Preview, etc.) when inspecting the PDF files. You'd think the pixel dimensions and dpi would be prominently displayed as it is for image files.

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PDFs don't have a DPI, AFAIK. They are simply document containers. They can contain images that, themselves, will have some sort of DPI based on their resolution vs. their size inside the PDF canvas. When creating PDFs, you can often down-sample the images contained within, but that's the only time I know if setting DPI values in a PDF. –  DA01 Feb 8 '12 at 23:38
    
@DA01, that may be the case and it explains a lot. However, when I inspected my PDF created from a 3300 x 2550 pixel source, I did not expect to see a size of "792 x 612". Those smaller dimensions would exactly correspond to a shift from 300 dpi to 72 dpi using the same 11" x 8.5" paper size. As it turns out, "792 x 612" is 'points' and not pixels, hence my original confusion. –  Sparky Feb 9 '12 at 1:13
    
For all the modernizations the design and DTP worlds have gotten used to over the past 3 decades, it boggles my mind that we grasp so tightly to the old world measurements of points and picas. ;) –  DA01 Feb 9 '12 at 3:56
    
@DAO, I don't believe I'm grasping onto anything from the old world, AFAIK... I mainly deal with graphics for websites and measuring in pixels alone suits me just fine. I just don't have the expertise to speak on the traditions and conventions of the professional printing world. –  Sparky Feb 9 '12 at 4:13
    
oh, I wasn't saying you were. I was just poking fun at Adobe and the industry as a whole and how we still have tools that use points and picas when it's such an antiquated measurement. –  DA01 Feb 9 '12 at 4:27
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