Hi guys, Thanks Larry for fielding Stefan's questions while I've been mostly out of contact for the last few days. Good discussion.
As for the API, I like how the details have been fleshed out so far. I have one nitpick surrounding the assumed alpha stuff. It seems like the value of spec.alpha_channel can mean two distinct things: 1) The ImageInput knew what the input channels were, and none of them represented alpha. 2) The ImageInput had no idea what the input channels were, and just gave up on trying to figure out which was the alpha channel. I would think these two cases have very different desired semantics from over(). For case (1), it makes sense to assume complete opacity as you've suggested for 3-channel images. For case (2), you can't decide what to do; the output is poorly defined and over() should probably fail. Unfortunately it seems like we've mashed both these cases into a single indicator spec.alpha_channel. Could we allow spec.alpha_channel to have a different negative value (-2 for instance) to indicate confusion as to the alpha channel, rather than that it's simply missing? Perhaps represented by an enum value for clarity? ~Chris _______________________________________________ Oiio-dev mailing list [email protected] http://lists.openimageio.org/listinfo.cgi/oiio-dev-openimageio.org
