With around 1 in 12 men suffering from colour blindness, it's a really common problem -- but it's incredibly difficult to understand what it must be like to suffer from. Fortunately, Etre now has a simulator which lets you see the world through the eyes of the colour blind.
The simulator will spit out any photo you upload (less than 1000 pixels squares or 100Kb in size) and display it in one of three flavours of colour blindness: Protanopia, Deuteranopia (forms of red-green colour blindness) or Tritanopia (blue-yellow colour blindness).
In the image above, the original photo is on the left, an image adjusted to show Protanopia is in the middle, and one filtered to show Tritanopia is on the right. It's a really interesting insight into how a significant proportion of the people around you see the world. [Etre via BoingBoing]
Image by Mark Lagneau under Creative Commons license