We support exporting to a JPG image of 1080 pixels x 1080 pixels.
The exported JPG image can be viewed and printed using any standard software for this purpose (e.g. the native Preview application in Mac OS X, or the native Windows Photo Viewer program in Windows).
We recommend printing up to 5" x 7"-sized prints-- actually 5" x 5" (13cm x 13cm), since the images will be square-- from an exported JPG, suitable for framing on a desk.
We do not recommend printing posters of any size, nor any other kind of large-format printing. Keep in mind that the primary purpose of the Lytro Light Field Camera is creating living pictures to be shared online, not printing or exporting 2D images.
The DPI (Dots Per Inch) of printed pictures depend on their size. Since we export JPG images at a fixed 1080 pixels x 1080 pixels, therefore the DPI is higher (better resolution) the smaller your choose to print your exported JPG image.
You cannot currently use Perspective Shift to create an exported JPG image. You must "refocus" the living picture to one particular focus point for this purpose.