Tim Shead wrote:
Suppose that I actually want to convert floating-point RGBA data to 8bpp integer RGB (I'm going to display the alpha separately, say). ... <skipped> How would you handle this on a case-by-case basis?
Hi Tim, This is described in Section 16 in the design guide. You can create your own color converters with arbitrary conversion policy. If you want to change the color conversion in only a few cases, you simply subclass GIL's default color converter. Color conversion functions take an optional color conversion object. Pass your converter there. Lubomir _________________________ // make the default use GIL's default template <typename T1, typename C1, // source channel type and base color space typename T2, typename C2> // destination channel type and base color space struct my_color_converter_impl : public color_converter_default_impl<T1,C1,T2,C2> { }; // provide specializations only for cases you care about template <typename T1, typename T2> struct my_color_converter_impl<T1,rgba_t,T2,rgb_t> { template <typename P1, typename P2> void operator()(const P1& src, P2& dst) const { dst.red = channel_convert<T2>(src.red); dst.green = channel_convert<T2>(src.green); dst.blue = channel_convert<T2>(src.blue); } }; // create a color converter object that dispatches to your own implementation struct my_color_converter { template <typename SrcP,typename DstP> void operator()(const SrcP& src,DstP& dst) const { typedef typename pixel_traits<SrcP>::channel_t SrcChannel; typedef typename pixel_traits<DstP>::channel_t DstChannel; typedef typename pixel_traits<SrcP>::color_space_t::base SrcColorSpace; typedef typename pixel_traits<DstP>::color_space_t::base DstColorSpace; my_color_converter_impl<SrcChannel,SrcColorSpace,DstChannel,DstColorSpac e>()(src,dst); } }; int main(int argc, unsigned char* argv[]) { rgba8_image_t a(100, 100); rgb8_image_t b(100, 100); copy_and_convert_pixels(const_view(a), view(b), my_color_converter()); }