opencv/highgui.go
func ConvertImage(src, dst unsafe.Pointer, flags int) {
	C.cvConvertImage(src, dst, C.int(flags))
}
func ConvertImage(src, dst unsafe.Pointer, flags int) {
	C.cvConvertImage(src, dst, C.int(flags))
}
/* utility function: convert one image to another with optional vertical flip */