Gimp has a wide variety of tools at your disposal for colouring an area. Here Michael Bates shows you how to use the gradient tool to selectively colour the iris of an eye.

If you want to flip or mirror images then you can use the free GIMP tool. It is very easy to do so using this image editor for Windows PC.

3 Now select the Gradient tool (Shortcut key L) making sure the foreground / background colours are set to black / white (1). If you've been using different colours press key D to reset.