Shouldn't display drivers have a "color blind" mode that would alter colors to make them perceptible? It seems an overkill to ask for the whole web to change.
Its not like assistance tools don't exist, but by squishing all the information in an image into a smaller visual space that I can distinguish, it makes everything look worse. Which is fine because I only really need to be able to distinguish difference in color that precisely about once a month so I only use a tool when I need it. Most colorblind people don't have enough need to even have a software tool.
I am always going to be using a computer with normal colors, as are my cohorts. You can accommodate us or not, the burden is on us. But that means we are going to think your website looks bad and/or maybe isn't even worth our time if we have to muck around with tools to be able to use it.
Heres an example of what it does: http://imgur.com/a/giSxg and how bad it can look: http://imgur.com/wlWgC The top is normal, the rest are transformations I'll use (the 2nd image is the one I usually need).
In the meantime, any developer can make their own site more color-blind friendly without waiting for the drivers or the whole web to change. Why wait for someone else to solve a problem you can solve right now?
I don't think it's as easy as you make it sound. The hypothetical driver would need to map everythink produced for "standard" trichromatic vision "down" to dichromatic vision in a meaningful way, maintaining contrast where it is relevant, but how should the driver know? (Maybe I am overestimating the technical challenge, so please correct me if I am wrong)
I think the solution can only be to make sure semantically relevant differences in color (e.g. different positions in a chart) can be identified by people with dichromatic vision, e.g. by not using the popular disticton of light red vs. light green. Quickly viewing a design through one of those filter programs is no big tasks and should be part of basic accessibility checks.
This doesn't mean you can't use all kinds of colors when they are not relevant to understanding, [edit: removed direct reference to deleted parent content]
Oops i deleted the comment hastily. I don't see the reason why it's impossible to calibrate a mapping according to the specific user's color blindness. That should be enough to cover most cases, apart from the cases where you are actually asked things like "punch the red monkey"
A mapping of a 3 dimensional space to a 2 dimensional space will bring some points (colors) too close together, this happens with the missing color cones. So now the driver tries to correct this by changing the mapping from 3d to 2d color space, in order to move green and red (for example) apart in the eye of the color blind person. The likelihood that this mapping will bring together other colors, which before were meaningfully apart, is high.
The mapping could work like high dynamic range mappings, trying to take into account local image features but this would probably make everything look really garish :(
I agree that a switch/mode in those color-modifying lense programs could be to remap color channels so a color blind person trying to read a specific chart or website could temporarily remap colors in order to better tell apart the colors used.
edit: disclaimer: I don't know about anybody with limited color vision personally so I just try to be careful assuming the problem could be solved easily. If testing with actual people with this condition proves me wrong, great.
I'm not sure it's that simple (but that's another discussion that's going on right now =)).
Aside from that, some of the design lessons and considerations that come from considering color-blind users tend to be good design principles in general.So - they may be good considerations to make anyways.
