The lawsuit claims users are fooled into seeing many more colors because the monitors use technological tricks that create an illusion.
The woman is seeking class action status for the lawsuit.
The lawsuit accuses the Cupertino-based company of falsely touting that ability even though it knows that 20-inch iMac monitors can display only 262,144 true colors.
Apple said the company doesn't comment on pending litigation.
The Associated Press contributed to this story.
