: When creating PDF from an image, what determines the screen dimensions when viewed at 100%? I would like to use pdf for ease of use and annotations when creating previews of my screen designs.

@Rambettina927

If you're trying to match the size of the graphics from Photoshop to PDF on the same device, you shouldn't have any problem: 100% in Acrobat is the same as Print size in Photoshop. Both apps adjust your display size according to the dpi with these view settings.

In the end, Acrobat really isn't intended for web work. It's geared around faking your print output on screen. Within your P'shop doc, you can preview what Acrobat will try to do by looking at the Document size ...



For web work, I usually check my designs on three different monitors with progressively degrading pixel density. If the project will be seen on mobile or tablet devices you have a really long list of possibilities on your hands ;)

Vote Up Vote Down

@Murray976

Every screen has it's own resolution. Or rather pixel density.

Consider a 20" (diagonal) monitor:

A monitor set to 2560x1600px has a ppi of about 137

A monitor set to 1920x1080px has a ppi of about 102

A monitor set to 1440x900px has a ppi of about 89

I post "about" because actual physical size of the monitor is a factor as well. A 20" monitor with a 2560x1600 resolution will have a higher PPI than a 30" monitor at the same resolution. (This is the entire theory behind "retina" displays - huge resolutions on a small screen).

If you create a document at 300ppi and tell Acrobat to view it at 100%, Acrobat takes into account the monitor's pixels per inch and tries to match the monitor ppi to the document ppi. So a 300ppi document on a monitor with a pixel density of 100 would show 3 pixels for every 1 pixel of density. A 100ppi document on a 100 pixel dense monitor would be a 1:1 ratio. This is how Acrobat determines "100%".

If you want to accurately display sizes in Acrobat you need to alter Acrobat's preferences. If you go to Preferences > Page Display there is a field to input Custom Resolution. Input your monitor's PPI in that field and 100% will be much closer to actual size regardless of what a document PPI is. You'll also see an option in Page Display preferences to simply use the system settings. You can use that as well if it is reading a value. Not all systems will have a default value other than the standard 72/96ppi however.

For a close estimate at your monitor's pixel density you can use this calculator: Pixel Density Calculator

Note, the calculator will only get you close. It's not 100% accurate. For example it tells me my Monitor PPI is 100.63. However, using 100.63 in Acrobat causes all kinds of display errors. So I rounded to 101. If you want to be 100% accurate in the pixel density calculations you need to do the math yourself since every monitor manufacturer will have a slightly different variation for a monitor's size. The wiki article I linked to at the top of this answer explains the math behind pixel density.

Vote Up Vote Down