Fig. 7
From: Crown-of-thorns starfish have true image forming vision
Contrasts between corals and the surrounding water within the coral reef environment. Contrasts were measured on images taken through a blue filter with a transmittance curve similar to the spectral sensitivity curve of the starfish eye. The contrast at 1 m measured 0.43 for the coral boulder and 0.18 for the blue staghorn coral. Two measurements were done on the same small reef, the first with the sun in the back and the second facing the sun