Size of image for contact entry


Hi all

I have a Galaxy S2 bought in Australia, flashed myself to ICS 4.0.3 US WiFi version [most manufacturers, Samsung and Motorola for example, are unbelievably slow in getting out updates. I imagine if their CEOs had to point to Australia on a map they'd stuff it up]

I'm getting things organised, and though it'd be nice to finally put pictures on my most often used contacts in the phone book. What size should I make the images, so that the phone doesn't have to resize them, or in other words, so I have more control over what they look like on the phone, and possibly save a little space. I'm also wondering if I can use a transparent colour for backlgrounds.

Would these same photos work/look the same way on my Xoom, again, flashed up to US Wifi JellyBean 4.1.1