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Colour Adjustment - Part 1 - part 2 of 1 2 3 4

by Mike McNamee Published 01/10/2002

This is encouraging for those who worry that they have poorer colour vision than their peers, but there is not doubt that some people seem to have better judgement than others. If Dr Birch is correct (and who are we to contradict!) then the trick must be to learn from our peers who are judged good at it. Another interesting snippet from Dr Birch is that colour discrimination goes off with time away from the job; you need to break yourself back in after a long holiday or time off work! The problem is two-fold for the colour printer, deciding which way the colour is out and then how to make it right! The advice that filters through seems to be consistent; train yourself up, learn from a more experienced colleague and lastly don't give up. It might also pay to visit the site at

http://www.vieo.com/~kinga/CVDtest.html

and test your colour vision. If you find that you are colour blind take up monochrome photography or try harder!

Here are some general pointers

1. The eye is quite discriminating over colour - watch that you don't end up chasing an impossible standard.

2. The trained eye is even more discriminating, better than many instruments.

3. Practice improves performance.

4. Learning alongside a skilled practitioner is useful.

5. Viewing conditions are important and include - sufficient illumination - correct light colour - correct surrounding colours (don't have jazzy wall paper!) - no glare, especially on your monitor

6. Colours in the green part of the spectrum are hardest to pin down and differentiating cyans is the hardest task.

Key facts:

The eye can discriminate 3 million colours.

There are about 1.6 million pigment colours

A 24-bit CRT screen can display 16.5 million distinct colours

The appearance of a small patch of colour is biased towards the complementary colour of its background e.g. a small patch of yellowlooks reddish on a green background and greenish on a red background.

The eye is sensitive to the size of the colour patch that is viewed. Standard view angles for test patches are 2° and 10°. This concentrates the viewed colour onto the cone rich part of the retina.

We learned a few other little facts on our travels through the world of colour vision defects. For example Viagra has been shown to temporarily impair colour vision - there your mother always said it would make you go blind! Monet painted yellow in his late middle period as his cataracts yellowed his vision and went back to painting blue again after an operation had restored his colour perception to normal.

We can use the list above to guide our behaviour when making colour judgement. In general terms you should rely on your female partner, wife, sister to assist you. As well as two brains being better than one, if you call them in late in the process they will not have been sitting there accumulating eye strain and colour bias, a process known as chromatic adaptation. Also you should take a break from your labours before making a final decision on the colour balance of your image, your first judgement is most likely to be correct and this includes your first impression after a break. Also you should take your time and while this goes against the advice last sentence to some extent it is a fact that only experienced colourists are able to make fast judgements.

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Contact Mike McNamee

1st Published 01/10/2002
last update 09/12/2022 14:52:34

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