Do you know what your design looks like when viewed through the eyes of someone that has a colour vision deficit? Not everyone can see all colours, but they do need to be able to recognise what different colours can mean. This of course is especially important on some signs, particularly safety signs and notification signs. While accommodating colour blind viewers is not yet a universal requirement to assist those with this disability, many countries do require such an accommodation. This means there is a precedent for constructing design work in this way.
If you are designing something specifically for colour blind viewers, it can be done. Here are some ideas. But firstly you need to know about the different types of colour blindness.

Red, orange, and yellow don’t appear as brightly to these people. These colours may appear as black or grey to them. People with protanopia also have difficulty telling the difference between violet, blue, lavender, and purple.

People with deuteranopia cannot distinguish between red, yellow, and green. These colours all look the same to them. Unlike people with protanopia, however, they do not experience the colours appearing dimmer than they really are. They experience the full brightness of the colours they see.

If you’re not colour blind, how can you experience what colour blind viewers will experience? Photoshop can simulate that experience with these two proofing commands:
View > Proof Setup > Colour Blindness – Protanopia Type
View > Proof Setup > Colour Blindness – Deuteranopia Type

These commands allow you to see the way designs will look to people with the two types of colour blindness listed above. Once you know how a colour blind person will actually see your design, you can use all of the other Photoshop tools at your disposal to adjust the design as needed. This will help you design documents and signs that are truly viewer friendly to colour blind people.
The most important thing to remember is that for most people with colour blindness, it is not so much distinguishing one colour from another that is the problem, as it is differentiating between shades and brightness levels of similar colours. You can do your colour-blind viewers a tremendous favour by making colours bright and never mixing gradients of shades of a colour on a document or sign.

Google has also launched a new Chrome tool that allows developers to mimic visual impairments like colour blindness to help them fix accessibility issues on their sites.
Developers can use this feature by launching Google Chrome and heading to the browser’s developer tools. There’s a new section titled “emulate vision deficiencies,” which features a drop-down menu of vision limitations. Selecting one, such as tritanopia (a condition where a person cannot distinguish the colours blue and yellow), would allow developers to mimic the condition, changing the colours of their site so they can see if it’s difficult to read without those specific colours.

ABOUT 300 MILLION PEOPLE ARE IMPACTED BY COLOR BLINDNESS – or 8 percent of all men and 0.5 percent of all women, are impacted by colour blindness.

Google’s new developer tools follow the release of Firefox’s visual disability dev tools. The inclusion of these dev tools in both browsers is important, as both web browsers display sites differently.