Colour blind artists: do the Vischeck transformations work?

EDITOR: I am a retired GP and a deuteranope and for these two reasons I have been interested in the handicap of abnormal colour vision, especially in the practice of medicine. Recently, you were kind enough to publish a paper by me and my colleagues on this subject. I also paint as a hobby, so I was very interested in the paper by Cole and Harris about the protanopic artist Clifton Pugh, who despite his severe colour vision deficiency was a highly successful and much celebrated artist. It is heartening that those of us with severe colour vision deficiency can, if we have the creative talent, paint in ways that please the viewers of our work. I was interested in the transformations of some of Pugh’s paintings in the Cole and Harris paper to the colour appearance for a protanope using the Vischeck algorithms. They show the colours of the paintings as we presume Pugh would have seen them. These transformations no doubt help normal colour vision observers appreciate the coloured world of those of us with dichromasy and help them understand the mistakes we make. Although transformations of this kind have been around for more than a decade, there have been few systematic studies to validate them. The Cole and Harris paper contains a systematic validation but for only one protanope. I thought your readers might be interested in my observations of the paintings by Clifton Pugh that are reproduced in Figure 3 of the Cole and Harris paper, each one paired with a Vischeck transformation to how Pugh saw the colours of his own paintings. Of course Pugh was a protanope and I am a deuteranope so my observations may have limited value. The protanopic transformations of paintings A, B and E looked the same as the normal colour paintings for me. In painting C, the patches of colour (are they red, green, brown or orange?) are darker in the transformation and are hard to see against the background. In D, the curled tubing is darker in the transformation, as are the ankle straps in the bottom pair of paintings. In F, the right side of the chair is darker in the transformed picture than the normal colour one. The curtain (red, green, orange or brown?) on the right of the man in the normal picture is black in the transformed picture and cannot be distinguished from its dark background. You will note that most of the differences that I can see between the normal colour and transformed images of Pugh’s paintings are to do with darkness and lightness, not differences in colour. It seems the Vischeck transformations do a pretty good job. I said that I was an amateur artist, so I include one of my landscape paintings (Figure 1), in which the colour normal observer will note that I use red, pink, yellow, brown and blue, or so my colour normal friends tell me. The deuteranopic transformation is reduced to yellows and blues, as the theory of dichromatic vision predicts. For me these two pictures look the same except that the red of the two roofs on the left of the pictures look darker in the transformation than in the normal picture.