Conversations on Colorblindness
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Part nine of my conversation with Dennis G.

Dennis wrote -

In those color text boxes I sent you I would say my first 4 (F,C,A,D) would work for me to read text on a WEB page. B is readable with great effort and E I can only tell something is there because I put it there and know where to Normal vision people can't read E either. These comparisons really help each other to understand what the other sees. All our comments of what we see really doesn't explain things as well as these color box/text test. It sure sounds like you are protan like myself, but I have trouble understanding why you have problems reading the sixdegrees.com WEB page which is combinations of blues and grays.

I was going to make the comment that if one stuck to blues and greens for there WEB page designs then one would be OK with most color blind people. By the way do you find all the all boxes in the test unacceptable for a WEB page except for F?

I would place the readability of the six.degrees.com WEB page at about a level with box A for me.

Marty wrote -

Actually I found all the boxes very difficult to read, with some bordering on impossible to read. F is the only one which is marginally acceptable but I wouldn't use that color combination. These boxes represent shades of the same color (or in the case of the green on yellow colors that look the same to me). None are readable. For something to be readable to me, or even viewable without great difficulty, I need either light/dark contrast of close to primary color differences. Light green is green mixed with large amounts of yellow and so looks the same as Yellow to me. Purple is red mixed with large amounts of blue and so it looks the same to me as blue. I suspect that the same is true of the other boxes.

As an experiment, look at the hex codes that defines for the boxes. This is a three-part six character code set which defines the mix of colors (red, green, blue) and the intensity of each that went into making up the colors one hex character for each rgb color. The hex codes range from 00 to FF with 00 being none and FF being very intense.

"The color code are made up of 3 2-digit codes with each 2 digit code representing the amount of red, blue or green that makes up the color. The digits are not base 10 numbers which make them look strange to most people. They are actually hexadecimal or base 16. So 10 in hexadecimal is 16 in base 10. A color that starts with 00 has no red and a color that ends in 00 has no blue. A color that starts with FF has full red and a color with FF as its middle pair of digits has full green.

There now several utilities for most computers to determine Netscape color codes. There are also some other sites which have cgi programs running which can help in choosing codes. This page was meant to be a cross section of the 16 million codes now available.

Not every browser displays color the same way. For example, Netscape on Macintosh and Windows will sometimes dither color that make up the background. The dithering pattern makes text difficult to read. A solution is create with a graphics program a small square image filled with the color that you want for your background. "

The way the computer mixes colors, or at least how the web browsers do, may be different than how they might be mixed in a full spectrum natural light environment. Let me know what you think.

Last updated March 5, 2001