If for some reason you would like to crop one of your photos to a 320x480 size then all you have to do is take a screen shot of the picture that you have zoomed in on it in the photos app. so, go into your photos app and select the picture that you want. then, zoom in on it so that it shows all of parts of the photo that you want. in other words, the edges of the screen are the new edges of the cropped photo. once its in position, make sure that the left and right arrows are not on the screen, and hold down the home button wile you press the sleep/wake button. this is how you take a screen shot. after that, hit the home button and then go back into the photos app and the cropped picture will be under saved photos. you actually dont have to do this if you want to crop a picture for your wallpaper cuz you can move and scale a pic for a wallpaper anyways. this is if you want to create a whole new picture with different dimensions as the original. hope you found this useful.