[robski]

I can see that the down sized version has stronger colour in firefox, IE and Chrome.

I have uploaded files at 1024 px with WPF not resizing so I think anything above this gets downsized to 1025 px

I had colour vision and related problems explained to me by an optometrist, The biggest factor is genetics. A gene related to colour vision is found in the X chromosome. If this gene is missing or impaired you will have colour vision problems. Men only have one X chromosome (YX) while Women have two X chromosomes (XX). So if a Woman has a problem with this gene in one X chromosome she has a backup of the other X chromosome. This is why there are far less Women with colour vision problems than Men.

Now with regards to how people see the spectrum (rainbow) of colours. Consider the range of colours like the bellows of an accordion. Colour blindness has the effect of compressing the range of colours to a point where you may just see a red or green instead of all the subtle shades of red and green. In some cases the compression maybe so severe that a colour is missing from the spectrum. Women usually see a very broad range of colours and hence the reason why more womem are colour consultants/specialist than men.