This paper presents biological evidence for camouflage breaking using the convexity of the intensity function. Some animals use apatetic coloring especially to prevent their detection by graylevel convexity. This implies that other animals might be able to break camouflage based on graylevel convexity. We demonstrate the effectiveness of convexity based camouflage breaking using an operator ("Darg") for detection of 3D convex or concave graylevels. Its high robustness and the biological motivation make Darg particularly suitable for camouflage breaking. As will be demonstrated, the operator is able to break very strong camouflage, which might delude even human viewers. Being nonedge-based, the performance of the operator is juxtaposed with that of a representative edge-based operator in the task of camouflage breaking. Better performance is achieved by Darg for animal as well as military camouflage breaking.