clipped from www.ephotozine.com Create a rainbow coloured eyeball using Gimp Create a rainbow coloured eyeball using Gimp - 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. In Gimp there are a wide variety of tools at the user’s disposal for colouring an area. Here we are going to learn how to use the gradient tool to selectively colour an area, in this case the iris of an eye, and to make the colour appear more a part of the image than if we dropped the colour straight into the image and left it.