Hi Christian,
Only for rgba gil is using partial specialization since it's using the rgb equivalent to do the wanted conversion. I think it's best to stick with total specialization to avoid confusions and/or breaking other people's code.
The goal of creating this generic conversion is that I can still make the conversion using an intermediate rgb colorspace if there is no specialization. I think I just said that. ;-)
For me, we can do that for all colorspaces. Sorry, I'm not sure to understand your position. You are agree to remove total specialization, even for rgba ? Are you agree to create a generic conversion from Colorspace to C2 for all colorspaces ? default_color_converter_impl<C1,rgba_t> // to remove default_color_converter_impl<rgba_t,C2> // do the same thing for all colorspace
Even when converting from gray to cmyk you wanna create a temporary rgb value? I believe this is a bad idea for various reasons. Please correct me when I'm wrong.
I think there is only two problems: * approximation * performance But if we want to correct these problems we have only to create the missing specialization. So I don't see any problem. It's always interesting to have all conversions. I don't think we will have a specialization to make the conversion from hsl to cmyk in a near futur. So in these cases propose a solution with approximation and performance cost sounds good to me. And it works fine with user custom colorspaces. Regards, Fabien