Maybe a little more strength to it to make it more noticeable. But you get the idea. Now we'll use layers to tint stuff.
Start with this image: 
Go to colour, click on colorization and play around with that to get different colours. Once you think you've got it, move on to this:
Open a new window, and paste this on the Background layer: 
As you can see, this image has a bluish green tint with a low saturation to it. What you want to do now is create a new layer (see layer window by pressing Ctrl+L). To create a new layer click on the blank square in the layer box. Call the layer Batman Control or something.
Paste that in it. You'll notice Batman will need some resizing, so click on the resize/scale tool in the Gimp toolbox, and click on the image. A box will pop up, click the chain to lock the proportions and then resize batman as you would it paint. Once finish click on Scale (in the window that popped up).
Now using the toolbox, select the magic wand tool. Set the threshold to something like 20 or 30 (that is how sensative it is to similar colours you've clicked on.) Click on the white area and once you think you've got enough of it, right click and select delete/clear. Now you can see the background but Batman's tint is off!!!
Duplicate this layer. Do this by rightlicking the Batman layer and select duplicate or click on the duplicate button (looks like two photos). Now select the top layer and go to colourize. Change the hue to a blue colour matching this one. Don't worry about the saturation, contrast, brightness or strength yet. Once the colour is matched, accept it. I know it's too strong at the moment, but now in the layer window, (with the top layer selected) lower the visabilty or the opacity of the layer so we still get som yellow and colour from the belt and some skin colour. Right click the top layer and click merge down so now Batman's colours are modified. (NOTE: DO NOT MERGE BATMAN WITH THE BACKGROUND) Now work on brightness/contrast and hue/conrast to match it perfectly. Save the image as to an extension of .xcf (or .psd for photoshop users) AND a jpeg file. Keep the xcf/psd file for yourself because we'll continue working on this picture later.
