Part three of my conversation with Dennis G.

Dennis wrote -

You are welcome to include all the material I write about. You can also include my name/E-mail address. I would be happy if your inclusions spark more interactions for me.

Marty Replied -

A movie or show where there are color differences but where it doesn't necessarily make much difference what they are so long as you can tell that there are differences are fine, but sometimes they put title text in red on black, or yellow on green, or use one of the combinations which I can not see, or can only see with difficulty and then I am reminded of my disability.

Dennis wrote -

I have had some problems with maps, but I have never noticed a problem seeing any type of red/black graphics or green/yellow graphics. I know I probably don't see them as well as "normal" vision people. Maybe I should say that I have never been reminded of being colorblind when viewing movies or text. As an example, I have no problem with the USA-TODAY news paper's weather map or the weather channel's maps. My main problem is with some history type book maps. But then "normal" vision people have to work at seeing maps too.

As I have said, I have "normal" blue/green vision and even maps with blue coding I have to work at to match things because in general I think people put too much on one map, even for "normal" vision people. It's sort of like using many lines of 12pt font for a view graph, it puts you off.

Marty Replied -

In my case I can not see the numbers or letters on the colorblindness charts, but can distinguish between different primary colors

Dennis wrote -

I can read a few of the colorblind charts. In alot of the cases I see a hint of a number. For example, have you ever seen the one with the word "color" and "onion" where one sees "color" if you are normal vision and "onion" if you are colorblind (or visa versa)? In this case I see both onion and color super-imposed on each other. The charts that have two of anything where one can thing can be seen by a "normal" vision person and the other by colorblind person usually confuse me because I either see both numbers or nothing at all.

Marty Replied -

I find it interesting that you as a color blind person should chose a profession where color differentiation would seem to be so important (i.e. spectral analysis., etc.)

Dennis wrote -

A spectrograph splits up light into pure single wavelength colors. This can be measured by instruments and thus, does not require color vision. I just got the idea of analyzing peoples vision using this instrument because it removes the human factors and judgements people place on color test charts. My profession doesn't center around this these types of instruments all the time. I have worked in what I would call colors in other regions of the electromagnetic spectrum, such as UV or X-rays and the same principles apply. Our color vision requires the mixing of colors. For example, you can not get purple or pink out of a spectrograph because purple or pink are not pure colors, but a mixture of blues and reds. It is our (colorblindness) red insensitivity that lets us see only blue sometimes when the color is actually purple or pink. Grab a Kodak red filter from the camera store (anything red) place a purple sheet of paper/plastic (what ever works) and a blue sheet on a table.

Have someone help get the purple if need be. To you they will probably look like different shades of blue and will appear very close in color. Now take the red filter and look through it. The purple sheet will look almost white and the blue sheet will be very dark. You now can get an appreciation for how "normal" people see the two sheet colors. Green and yellow will also work with this demonstration if the filter isn't too deep in the red.

Marty Replied -

Interesting though that color blindness may be due to a lack of sensitivity >to certain colors of the spectrum rather than a complete lack of rods.

Dennis wrote -

Again as I understand it rods have nothing to do with color vision. They help us see at night and that is why we (humans) don't see color very well at night. Rods also don't allow for sharp vision and that is why it is hard to see detail at night, even in soft light our rod are starting to provide most of our vision. Colorblindness is a problem with the cones. Normal people have three set of cones with peak sensitivity in the RED GREEN, and BLUE regions of the spectrum. Colorblindness is commonly call Red-Green colorblindness because it only affects either the RED or GREEN cone receptors in our eyes. If it is the RED cone it is called protan colorblindness and if it is the Green cone it is called duetan colorblindness. Blue cone colorblindness is very-very-very rare. 1% of colorblinds. Green (duetan) colorblindness is 3 time more common than Red (protan) colorblindness.

Marty Replied -

I on the other hand can see each of the lights equally well, and can see each one differently, but have difficulty telling the green lights from the street lights. (green light vs. blue/while light?)

Dennis wrote -

I find this statement very interesting... I can see the green light as very green in the day, but at night some lights do look like the (high pressure mercury lights or Blue-white) street lights. But the red light is noticeably dimmer than the green or yellow light. The classic symptom of a protan (RED) colorblind person is that red lights appear dimmer than they do for normal people.

You also said you have trouble with navy blues where I see these colors as good if not better than normal people. Every colorblind person I have met has said that the green stop lights look white to them. I am not sure what to make of this, but possibly human factors are involved.

If you have trouble see red LEDs then how does the red stop light look as bright as the yellow or green lights? Sometimes if I am far away from a stop light in the day I have trouble seeing the red light. Do you have this problem? Also, if I am a protan (RED) colorblind than most people I meet should be colorblind differently than me since only 1/3 of colorblind people are protans. Maybe I am a duetan (Green), but I have the classic symptom of not seeing red well. I have to look into this.

Duetans (Green) colorblind people, by the way, would see stop lights with about equal intensity as you described, but I don't understand the red on black problem you have with text. Read the internet article WEB site I sent. There's something to learn from this because I also don't have problems with browns and blacks. Maybe protan and duetan colorblindness affects some things the same way.

Marty Replied -

I can see red very well, but not red on black...

Dennis wrote -

I find that you see equal stop light brightness for all 3 lights and this statement interesting again. It would seem to me that red on black is hard to see because the red looks very dark to black which means your red sensitivity must be lower than normal. This my reason why red on black is hard for me to see sometimes.