Photoshop Document Sizes
In Photoshop's Image Size pallet there are two sections, Pixel Dimensions and Document Size and it's document size we're going to look at here.
Document size is about the size of an image when printed as opposed to when displayed on a monitor. They use different resolutions and if you send an image that looks great on a monitor to be printed but it comes back looking pixelated it's because you need a higher resolution for printing than for viewing on screen. We've covered this in 'Photoshop Image resize for Web' http://www.photographycourses.biz/res...
Hope you find this helpful
Mike Browne