help finding a tool in Photoshop

Ok, maybe I am wrong but I remember years ago using this tool in photoshop, granted it would have been a way older version.  But maybe you guys know where it is.  I thought you could select part of your image and there was something you could do to even out all the colors.  Like it blends it.  Not blur though.  Does this sound familiar to anyone?

Well, I honestly don't know that I understand your question, but it almost sounds like what you get when you go to Filter>Blur>Average.  You can do that on selections as well, or create a layer and set its blending mode and opacity with the result.  Anyway, an idea... maybe you can try to give a little more detail as to what you are asking for?