input: [Colour] Black [Muddy/Dark] On the negative side of black, it can show in a person who's hiding something to decieve another. It may possibly indicate imbalances as well. If seen in the outer edges it means holes in the field. The presence of black spots in the aura may indicate that it is imbalanced in some areas. That may mean that person has some negative habits that he or she should work on. Meditation sometimes helps to reduce these spots, as does things like exercise and sunlight. [Clear/Bright] 
output: Black carries with it both positive and negative meanings, despite it having only one tone. (There is no clear/muddy split here.) On the positive side, black is the color of protection. It can also mean deliberate withdrawal or internalization.