Mhmm, that's weird. For a quick fix the following is working: typedef rgb8_image_t image_src_t; typedef gray8_image_t image_dst_t; image_src_t dst( 100, 100 ); image_dst_t src( 100, 100 ); copy_pixels( color_converted_view< image_dst_t::value_type >( subimage_view( view( src ) , 0 , 0 , 100 , 100 )) , color_converted_view< image_dst_t::value_type >( view( dst )) ); I'll get back to you once I understand what's going on. Regards, Christian