What DPI should I have photos at for iPad?

Full resolution - as good as it gets . When the photo's are transferred to the iPad, optimisation will be done so keep them as good as possible I guess.

(It still doesn't make sense to me but that just me)

You don't save things at DPI - DPI is for when you print them. The question does not make sense - save them at full resolution.

My point is that in uploading photo's to the iPad 'Photo' App, there is a translation process which occurs which does this for you during upload and keeping photo's below that size has caused unpredicatable results. Just leave them at the same size as the original from the camera and it'll sort things out for you.

The dpi info isn't used on the iPad.

If your photo is saved at 1024x768, it'll be displayed at the full iPad screen size. Changing the dpi setting won't change a thing on the iPad display.

The dpi setting doesn't affect anything in the image file except a bit of metadata about the printing size. The image file itself will be the same. So set the dpi to whatever you want -- 72, 150, 240, 300, 1,000.

This does make a difference when you print, because the dpi on a sheet of paper is variable. Change the dpi and the printed size of the image changes.

Make sense?

-=-Joe

It will make a large file smaller - thats why backups are essential. If you lose your library, all you have is the reduced quality images on your iPhone or iPad.

My iPhoto library is currently 18.9Gig and on the iPhone its only 1.47Gig.

But it won't make a large file size smaller right?

If your files are managed by iPhoto or Aperture on a Mac, then yes it will. You need only compare the storage space allocated for your iPad photos against the storage space required for the original photos in the managing application. For example, I have 3 April Aperture albums currently installed on my iPad. On the iPad they require a bit more than 200 MBs of space. The original files that remain stored on my hard drive by Aperture take up 600 MBs of space. The amount of storage space saved will depend on the format and dimensions of the original files. I.e., the less compressed and larger the original file, the more space you will save during this automated optimization by iTunes as it syncs the content. Conversely, the smaller and more compressed the files you sync via iTunes, the less savings your will realize until you reach a point where no optimization takes place and the iPad file is the same as the original file. I don't think we can explain this in any simpler terms here.

As to the dpi vs. ppi (and/or lpi for that matter), I assume the poster was left-handedly attempting to point out that the terms have somewhat technical differences and should be applied more judiciously with respect to the medium or device to which you are making your reference. However, most of us did realize what you were trying/meant to say.

Whoever said resolution is only for printing is wrong. I re-sized mine to 1024 x 768 and they look great on the iPad. Full resolution was too much as it was taking iTunes too long to process them prior to the sync.

As Graham said, you will only save space on your main computers hard drive if you chose a lower resolution (or dpi). iTunes handles the resolution of all pics you transfer to the iPad, so unless they have a resolution that is lower than what the iPad can handle, they will always be reduced in size.

I personally would never start reducing the resolution of my photos. I keep them in raw format somewhere, then usually a high res jpg after editing, and on the iPhone for showing them around. (No iPad where I live yet.) If you are afraid you'll clutter your computer with large picture files, just get some external storage. It's cheap, and you really don't want to look back in a few years and wonder why your once beautiful pictures look so grainy on the new 35 inch screen.

Sockel, you bring up a good point that I failed to mention. I never reduce the size of my originals. What I left out is that I re-size a copy of my edited photos, leaving the original intact.

I use Picasa to edit my photos (I know, I'm sure there's better apps out there), but that's what I've been using and find it fine for my purposes. I edit my photos and then export copies of the edits to a separate set of folders that I sync with my iPad. When I export them, I choose 1024 x 768 for the size.

Sure, you can let iTunes convert them, but I found that it takes a lot longer to let iTunes process the photos than it does simply exporting them to a different size with Picasa.

But that aside, the re-sized copies of my edited photos look stunning on the iPad.

Changing the resolution DOES matter, but the dpi does NOT. A 1024 pixel wide image is smaller than a 2048 pixel wide image. But a 1024 pixel wide image is exactly the same size whether you've set the dpi to 72 dpi or 300 dpi.