iPhone users. Have you noticed in Pho­tos app pho­tos that are not exactly in the aspect ratio of the phone which is 2:3 (320:480) are letterboxed—with black on the sides, and when they are near that aspect ratio they snap to the edges to fill the screen?

I found out the magic num­ber is 80%. Imag­ine the width and height of the phone each bro­ken into ten parts. This gives you a ten by ten grid. In por­trait ori­en­ta­tion, land­scape pho­tos are let­ter­boxed with black on top and bot­tom and the width fills the screen. Increase the height of the image and the black parts get smaller and smaller. At 80% the image becomes fullscreen with its height fill­ing the height of the screen with the left and right sides spilling out of the screen. The same is true to the any ori­en­ta­tion of the phone and pho­tos. It’s 80%.

Basil Safwat of The Invis­i­ble has a post on how Mail app clev­erly han­dles bring­ing the user back to the top of the inbox when new mail arrives. Also check out my post on how the iPhone 4 phys­i­cal frame share sim­i­lar pro­por­tions with appli­ca­tion icons.