Is there known reason why the alternate uniform colors were discontinued in the later movies of the original trilogy? The field gray Mollo chose is certainly reminiscent of Nazi uniforms (in the same way that the bridge layout on the star destroyers are suggestive of slave galleys). (Veers has an entirely different outfit when he goes into battle on Hoth, however, and my avatar shows actor Julian Glover in another SF costume.) It cannot just be a matter of different services (imperial navy versus army), since when onboard Vader's command ship, General Veers wears the same gray uniform as the naval officers. However, in The Empire Strikes Back and Return of the Jedi, these alternate colors are never seen. Besides the most frequently occurring gray, there were also plenty of officers in black, and (during the meeting scene) one person in a much lighter tan. In A New Hope, John Mollo's Oscar-winning costume designs included imperial uniforms in a number of different shades.