This is a simple "whitepoint" correction plugin. It's ideal for images which have a slight color tint, and which contains some pixels which should be neutral grey.
I wrote this plugin as my mobile camera usually ends up taking images with poor color balance, and I wanted a simple tool to correct it. I'm publishing it in case anyone else finds it useful.
Select the Color Picker tool.
Use the Color Picker to select a Primary Color which should be neutral grey.
Select the Adjustments menu and select the Whitepoint plugin.
If not satisfied, undo, try another color and run it again.