The first generation Windows Phones had hardware that used both 16-bit and 32-bit color, but the operating system would force the display to use 16 color regardless. If you have graphics with smooth gradients then then you would end up seeing color bands on a 16-bit display. On Mango if a phone supports 32-bit color you can take advantage of it, but only if you ask! If you want to enable 32-bit color you will need to edit your WMAppManifest.xml. In the <App /> element add an attribute called BitsPerPixel setting its value to 32. That's all you need to do. After doing that when your application runs on a device with 32-bit graphics hardware it will display in 32-bit color mode.
Tags: Windows Phone