Red Roofs and Colour Blindness

Today's picture shows workmen busy putting a new roof on one of the blocks of flats on Back Bower Lane. To me the roof tiles look red and the building is constructed with red bricks and I was going to post this on the 1st for the Red Theme Day. Told by my good wife that the subject matter really isn't red, I took another picture for the theme post.

When I mentioned about my being colour-blind, some people obviously did not understand and thought I couldn't see colours at all. So to inform such people, here is what Wikipedia has to say on the subject:

Color blindness, (also known as Dyschromatopsia) or color vision deficiency, in humans is the inability to perceive differences between some or all colors that other people can distinguish.
The most frequent forms of human color blindness result from problems with either the middle or long wavelength sensitive cone systems, and involve difficulties in discriminating reds, yellows, and greens from one another. They are collectively referred to as "red-green color blindness", though the term is an over-simplification and somewhat misleading. Other forms of color blindness are much more rare. They include problems in discriminating blues from yellows, and the rarest forms of all, complete color blindness or monochromacy, where one cannot distinguish any color from grey, as in a black-and-white movie or photograph.

It goes on to highlight popular misconceptions:

Color blindness is not the swapping of colors in the observer's eyes. Grass is never red, and stop signs are never green. The color impaired do not learn to call red "green" and vice versa. However, dichromats often confuse red and green items. For example, they may find it difficult to distinguish a Braeburn from a Granny Smith and in some cases, the red and green of a traffic light without other clues (e.g., shape or location).
Color blindness almost never means complete monochromatism. In almost all cases, color blind people retain blue-yellow discrimination, and most color blind individuals are anomalous trichromats rather than complete dichromats. In practice this means that they often retain a limited discrimination along the red-green axis of color space although their ability to separate colors in this dimension is severely reduced.
It should also be noted that even though some people are unable to see some or maybe even any of the numbers in (e.g. red-green) color blindness test, the person might still be able to tell the difference between the colors in his or her everyday life.

Here is a page that might enlighten you on web design accessibility. I suspect that when I complain sometimes about not seeing text on a web page until I run my cursor over it and highlight the text, the designer doesn't understand what I'm getting at as they can see it perfectly clearly. The corollary to that is — I design my own web pages so that I can see text clearly against a particular background, but I don't know how that looks to folk who aren't colour-blind. Perhaps it looks garish to them. In fact I recall changing the background colour on some of my web pages at the request of someone who suggested the change would aid clarity.