The author has a color vision deficiency. Like roughly 7-10% of all males, his deuteranomaly makes it difficult to differentiate between some colors, like red and green. Color deficiency, or color blindness as it’s commonly referred to, doesn’t mean that he or people with similar conditions cannot see certain colors. They’re not invisible and he doesn’t see in black and white (a condition that is actually very, very rare). He can still use crayons effectively, find meaning in beautiful sunsets and even enjoy clear blue skies. What it does mean is that certain colors in the visual spectrum look a lot like one another and so he has a hard time sometimes telling the difference between certain colors and even shades.
Because of this, designing software and interfaces that will also work effectively for people like him takes a bit of concerted effort. Be cognizant of color blind accessibility issues. Of all the elements of design (line, shape, size, texture, etc.), color is probably one of the most used elements to pass on informational states. This is probably because it allows a designer to say many things without having to change the form or layout of the design. While there are a number of simulators and plugins that can help you “visualize” what a color deficient person might be seeing, he doesn’t recommend spending a lot of time with them. Instead, he would like to propose just a few simple guidelines along with plenty of examples to help the reader effectively ensure that a good percentage of their audience won’t misinterpret the intended message.
Be Kind to the Color Blind