[XP] Tileset Issue With Woods Large Tree and Shadow - Need a Photoshopper

So, every time I want to use the huge tree for something, I always find that the Shadow on the tree casts incorrectly on the player.  I have a solution, but dont have the Photoshop skill.  What I'd like to do is for someone to LIGHTEN the 4 tiles of the base of the tree so if a shadow from another tile is cast over it, the color matches correctly.

In photoshop, apparently color sampling the shadow color, adding a new layer, then changing the Opacity to exactly 50% matches the games transparency perfectly.  So I can add a shadow to an object that I want, any suggestions on how to UNSHADOW a similar way?

wrong area try posting here: http://rmrk.net/index.php/board,114.0.html