To a person with colour vision deficiency (colour blindness), some pairs of colours that other people can easily tell apart will be perceived as similar or identical. In the right context, this deficiency can be harnessed as an unusual ability. In particular, some combinations of colours can serve as camouflage, allowing a design to conceal information that is nearly invisible to a viewer with normal colour vision, but comprehensible by someone with the right form of colour vision deficiency. I explore the possibility of using dichromatic vision as a vehicle for a subtle form of steganography, present tools for processing digital images to achieve this effect, and discuss the possibilities of this rather specialized aesthetic domain.