This paper presents biological evidence for camouflage breaking using the convexity of the intensity function. Some animals use apathetic coloring especially to prevent their detection by gray-level convexity. This implies that other animals might be able to break camouflage based on gray-level convexity. We demonstrate the effectiveness of convexity based camouflage breaking using an operator (“Darg”) for detection of 3D convex or concave gray-levels. 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 non-edge-based, the performance of the operator is juxtaposed with that of a representative edge-based operator in the task of camouflage breaking. Darg achieves better performance for animal as well as military camouflage breaking.