>Thanks for the pointer. From what I see there, it seems that IM >doesn't support 16-bit grey-scale PNG, which is fine with me since >that's not what I wanted anyway. I forgot to ask, but what Q level of IM are you compiled at. If you are using Q8, then you won't get 16-bit pngs. You need to have Q16 IM to get 16-bits per channel.