Another simulator on the market that shows you what your image or website would look like to someone who is colour blind. This one is from a company called ETRE – for further details see http://www.etre.com/tools/colourblindsimulator/

In the image series below the left image is normal and the ones in the middle and right show protonopia and deuteranopia respectively.

For more on colour blindness see my earlier post.