Why This Topic

I myself am red-green colour blind. I find it is not very well understood. IN fact, until I took flying lessions when I was 22 yrs old, I never knew I was colour blind. After the fact, many things that happened to me in the past suddenly made sense.

Since colour blindness is not treatable or cureable in any conventional sense, little attention is paid to it by the medical community. In my limited personal experience, I found that most flying instructors have a better understanding of colour blindness and it's effect than most medical doctors do - even including opthamologists. I cannot answer all question here, only hope to raise some awareness of the situation and how it effects both visual observing and astro-photography.

- soapbox mode on -

I have greatly simplified the information contained here, and deliberately avoided any indepth, technical explaination of situations and events. I have also avoid some of the more "pollitically correct" terminology. I take absolutely no offense at anyone calling my condition "colour blindness", and in fact, I would be very offended if someone tried to paste some "visually impared" label on me. Fancy words and terms do nothing to correct my condition nor improve my quality of life. You may not agree with my attitude, but this is my web page, and my right to freedom of speech. Hope you enjoy it..

ps...for the record, I can't spell worth a darn either.....

- soapbox mode off -

What is Colour Blindness?

Absolute colour blindness - seeing no colour at all, so the world appears like a black and white photgraph, is very rare and easily spotted. The majority of cases of colour blindness are colour specific - such as a red-green deficientcy - the most common.

In these cases, the person who is colour blind may go through thier entire life not realizing it. As I said, it is not always well understood by the medical community. I personally went through a lot of physicians before I got some hard answers.

Who Suffers From Colour Blindness

Estimates are that 5 to 10% of the male population has some form of colour blindness. Amoung females it is rare - perhaps less than 1% of the population according to some reports. The gene that causes colour blindness is hereditary through the female. Daughters carry the gene, sons suffer from it.

What Are the Mechanics of Colour Blindness?

The light receptors on the back of your eye consist of rods and cones. Cones are the receptors for bright light and colour. Rods are the receptors for geryscale and low level light. Cones are centred in the middle of your eye, directly behind your eye lens, while rods tend more aorund the outside.

If you use averted vision during visual observing, you are actually trying to use your rods over your cones. In colour blindness, it may be that a person has more rods than cones, it it may be that the cones are not fully functional - depends on the individual and the specific form of colour blindness.

How Does Colur Blindness Affect Visual Observing?

There are a couple of ways. First, the ability to judge visual magnitudes of celstial objects is greatly affected by how our eye's respond to colour. I have noticed that my estimates, while consitant, tend to average 1/2 a mangitude lower than that of otehr observers. Ther stronger the colour is in an object being observed - whether it is a comet or a globular or a nebula, the birghter it appears.

The human brain is still the most advanced image processing system in the world that we know of. Strong colour cause the brain to interpret more birghtness. Each colour reflects different amounts of light. How most people judge contrast in a picture or scene is based on how much light is being reflected by different colours. Depending on the picture in question, if the scene were converted to a grayscale image, much of the contrast would disappear.

For someone who is colourblind, the different colours do not as easily affect judgement of contrast or brightness. The perception of contrast is based more on a grayscale. Look at famous B&W photogrpahers, or most B&W photography on the web. Notice how many if not most are men? I have heard time and time again from female photographers that they wish they could shoot more B&W film, but they have trouble imaging the picture in their head ahead of time. Perhaps some of these male photographers ahve a bit of colour blindness?

Another way it affects observing is a greater ability to see in the dark and the lack of effectiveness of averted vision. I find I see very well in the dark, and I find averted vision does very little to improve an image for me. Does this mean people with colour blindness are better int he dark? Not really, It is a little more in-depth than that.

People who are totally blind often have very acute sense of hearing. This does nto mean they ahve more sensitive hearing, it means because they depend on their hearing for so much, they have had to, out of sheer neccessity, train themsleves to be better listeners.

Even unconsiously, a person who is colour blind, and has few or defective cones, out of plain need, uses thier rods in their eye more so than the average person. Since rods are the low light detectors, by becomming more active, they allow better low light seeing. Does this mean people with colour blindness ahve sensitivity to bright light? In some cases, inclusing my own, yes - bright light, even plain, sunny noon - time daylight can be a bit overwhelming.

How Does Colour Blindness Affect Astro-Photography?

When a person sets out to capture an image in ANY medium - film, oil paint, CCD, wood carving, marble sculpture - anything - that person first forms an image in thier "mind's eye" of how the final product should or could look. Even in astro-photography were a person has a consious sense of "what will I find?", there is an unconsious bias o how objects should appear based on previous experience.

How we see depth of field, texture, contrast and birghtness are all directly influenced by colour. This is something that all good artists and architects throughout history have been aware of. Sometiems the most subtle shift or change in colour can have a major effect on the appearance of anything from a sculpture to a photogrpah to a building.

Therefore, a person who has any form of colour blindness sees and interprets the world about them differently than other people. It has been shown that colours interact with people even on an emotional basis, but again, this effect on someone who is colour blind may be absent or even the total opposite.

Take for example a photograph of any nebula that has been through image processing to enhance existing colours. For normal vision people, it may be a very positive effect. However, for those of us who are colour blind, that image may appear "forced" or false in some fashion. Instead of improving it's appeal, that photograph may actually disturb or repusle someone with colour blindness becasue of it's apparent falseness.

Therefore, a person with colour blindness performing astro-photography will have a totally unique set of expectations of even what makes a good astro-photo. If that person has some form of colour blindness and is not aware of that fact, they could easily be at odds with others over intrepation of photographs.

There are 3 images presented here. The original is a Hubble picture of Eta Carina, an image many of you have probally seen before. The second image is the same image may look to someone with a red-green colour blindness. The third image is a greyscale image.

Now compare carefully the second and third image. Image for a moment you are colour blind and the second image is how you normally see. Which of the two images appears sharper, to contain more detial - in genral - which of the two images appears more interesting?

This is not a very accurate representation of colour blindness, but it doesgive you an idea.

Click here for the same 3 images at once, but larger. Three jpegs at 104K, 96K and 56K.

Conclusion

Hope you have enjoyed this. As I gain more information, I will add it here. Drop back to the main page if you wish to leave me any e-mail comments. I always appreciate them

.......return to MORE menu.......

.......return to MAIN page.......