Color Alteration was the ability to alter the color of matter or anything else visible to the eye. Such a super power could have been an application of photokinesis, which allowed one to alter the spectrum of light shining on a certain object, making it appear a different color, or it could have simply been a form of camouflage, allowing oneself to change color so as to keep hidden much like a chameleon.
There were a variety of characters that had this ability. Color Kid for example was a 30th century superhero who could change the color of anything, however, Clayface and Starro could only change the color of their own bodies. Most shapeshifters could also alter their own color. Plastic Man was one of those rare exceptions of people that could not, as his power was only limited to changing his shape.
Color Alteration was very limited and some might have said it was quite a worthless power, but not when you really think about what all was involved with such an ability, for example, one with the ability to change color of objects could have actually defeated opponents such as Superman and Green Lantern. As an example, if someone with Color Alteration powers went up against Superman, all they would have had to do was change the color of the sun to a reddish color, which would drain the energy that gave Superman his powers.
Likewise, if a character with Color Alteration powers were to go up against any Green Lantern, all they would have had to do was change the color of every object surrounding them to a yellow color, which would make their power ring worthless.
It should also be noted, that a character with such an ability could have also been helpful to Superman or another Kryptonian who was being exposed to Green Kryptonite. A character with such a power could have easily turned Kryptonite from it's green color to blue, making it Blue Kryptonite and therefore harmless to any Kryptonian.