On Wed, Dec 21, 2011 at 1:30 AM, Tony Yu <tsyu80@gmail.com> wrote:

I think one of two things should happen:

1)     [uint -> int]: expand uint to *full* range of int.     [int -> uint]: unchanged (squeeze into range of uint)

2)     [uint -> int]: unchanged (fill *positive* range of int)     [int -> uint]: clip negative values from int

People very often represent images in signed integers, even though they only manipulate positive values, e.g. storing 0-255 in int8. So the conversion to signed should not spread those values over the entire range. However, I think you're right that we should add the clipping in 2 to avoid the conversion bias, along with a nice big warning. Regards Stéfan