I've been tasked with designing a touchscreen for an electronic device and I'm doing a majority of the layout in Adobe Illustrator CS6. The specs that I've been given are: Live area: 5.5"W x 3.13"H (buttons must stay within this range) Resolution: 732px x 444px Pixel pitch is 132ppi on horizontal axis and 142ppi on vertical axis (averages to 137 ppi). My question is what resolution do I need to export my vector button graphics at to look the best in these specs and not require any resizing by the coders? I can export each button as a png. Is that the best? If so, what resolution (137ppi)?