+#define wxIMAGE_OPTION_RESOLUTION wxString(_T("Resolution"))
+#define wxIMAGE_OPTION_RESOLUTIONX wxString(_T("ResolutionX"))
+#define wxIMAGE_OPTION_RESOLUTIONY wxString(_T("ResolutionY"))
+
+#define wxIMAGE_OPTION_RESOLUTIONUNIT wxString(_T("ResolutionUnit"))
+
+// constants used with wxIMAGE_OPTION_RESOLUTIONUNIT
+enum
+{
+ wxIMAGE_RESOLUTION_INCHES = 1,
+ wxIMAGE_RESOLUTION_CM = 2
+};
+
+// alpha channel values: fully transparent, default threshold separating
+// transparent pixels from opaque for a few functions dealing with alpha and
+// fully opaque
+const unsigned char wxIMAGE_ALPHA_TRANSPARENT = 0;
+const unsigned char wxIMAGE_ALPHA_THRESHOLD = 0x80;
+const unsigned char wxIMAGE_ALPHA_OPAQUE = 0xff;
+