The colour photos of dazzle schemes used in WW2 do indeed show 'natural' shades of grey, blue and green. The object of the exercise was, after all, to break up the outline of the ship and not to advertise its presence.
But WW1 photos and paintings do show much more drastic, high-contrast patterning, often zebra stripes. These were designed to confuse coincident image rangefinders (as used by the Royal Navy) and to this end they were effective. Unfortunately they had no effect on the stereoscopic rangefinders used by the enemy!