if you can get a small piece of the paint off the wall ( at least 1 sq inch), you should be able to take it to any paint store and they should have a device that will analyse the sample and attempt to get an exact match.(if your lucky) I have done this at SEARS and to some extent exceeded. More than likely, the device will direct you to a preset color that may or may not meet your criteria. If the color is close, then buy a small sample and try it. As the previous post stated, the color you see in the can will dry somewhat different o the wall. So good luck!