vischeck.com simulates colorblind vision and
daltonize corrects images for colorblind viewers.
I believe it to be an interesting tool for webdesigners and those working with color. Predicting how others perceive a message is very important if one wants to have success in spreading it. Also, it’s always a good practice to think that there might be people with difficulties in perceiving a message, and try to reach the broader number of users. For exemple, nowadays, in html, instead of using the <i> and <b> tags for italic and bold, the <em> and <strong> tags, for emphasis and strong, are widely used, giving reading instructions to web browsers, contrary to the first ones. That is, of course, for people with reading issues, such as blind people.
I simulated colorblindness with the Google logo, and this were the results: