Dumbledore raised his wand even higher, so that its light was thrown upon the walls, where something darkly red and glutinous was spattered over the wallpaper.
An expression of annoyance and displeasure passed over his pale handsome face, which seemed even paler than it really was, in contrast to his dark-red, wavy hair.
But after you've switched your toaster off and it's crawling down in the dull red face, it's still glowing, it's just doing it in colors that we can't see in the infrared.
Loaded up with carbon dioxide, the blood turns that dark red color again (shown as blue) and starts the return journey to the heart by going into small venules and then larger veins.
Duncan heard the grating of the rusty hinges, and darting to the spot, directed by the sound, he met a long line of dark red warriors, passing swiftly toward the glacis.