How does anodizing impact the mechanical & optical properties of aluminum?

Anodizing grows perpendicular to the surface of the aluminum.  That being said, whatever surface roughness/texture is there before anodizing will be there after the anodizing process.  Anodizing is only .0003 to .002 inches thick and has little effect on the mechanical properties. Optically, there will be a change in the emissivity of the anodized surface.