Click here to buy from Amazon. Mobile devices are used in all sorts of environments, and must be clear and easy to read when bright, dark, dirty, rain-covered, and so on. General heuristic principles should be followed to dual- (or triple-) encode information so that it is clear in all conditions.

Therefore, the design of mobile devices should not be significantly affected by considerations for users with color vision deficits. Practically, many, many interfaces are still single-coded, with (for example) red type used for important notices and no use of iconography or type weight to reinforce this.

The information and guidelines in this appendix should serve not just as a reminder of how to address the needs of a significant portion of the population, but also of how color vision can fail every user in certain conditions. If colorblind users are considered in design, the product will work better for all users.

We Are All (Sometimes) Disabled

I have to credit the concept of "temporary disability" to the always correct and clever usability expert Robin Christopherson, but it applies especially to mobile and color. Simple factors like glare can make a screen lower contrast and effectively monochrome. Multi-encode every control and indicator as though designing for colorblind, nearsighted users. Everyone is like this sometimes, especially on mobiles.

I also say that way more people have a color deficit than in the numbers I list below. I have minimal clinical data to back this up, but in numerous usability tests have encountered people who have less inclination to notice colors. For example, we were testing a new web portal, and most users were annoyed by how prominent this yellow banner was at the top of the page, and always noticed the bright yellow triangle warnings near it. Except one of the users who, despite otherwise clearly having color vision, just did not seem to notice, and thought the whole page looked drab instead.

General Information on Color Deficits

Color vision deficiency (commonly referred to as colorblindness) is a condition in which certain colors cannot be distinguished or can only be distinguished with difficulty. It is most commonly due to an inherited condition. There is no treatment.

Red/green colorblindness is by far the most common form. Blue/yellow and other forms also exist, but are rarer and harder to test for. Complete colorblindness (seeing only in shades of gray) is extremely rare. Color deficiencies of one sort or another occur in about 8% to 12% of males and about 0.5% to 1% of females (of European origin).

These official numbers are likely low, because color vision deficits are not obvious to the individual with it. That is just how they see, and the reduced color vision anomalies are subtle enough that people may never discover they are not seeing colors as brightly. But, it matters a lot for design.

Clinically, disturbances of color vision will occur if the amount of pigment within a cone is reduced or if one or more of the three cone systems are entirely absent. The gene for this is carried in the X chromosome. Therefore, colorblindness occurs much more commonly in males and is typically passed to them by their mothers. Reduction in pigment in one or more channels is more common than the loss of one or more sets of cones; therefore, most have a strict color deficiency, and perceive certain color channels more poorly, versus not at all.

Types of color deficiency

The following are various types of color deficiency:

Protanomaly (partial red-green, 1% of males)

Deuteranomaly (partial red-green, 5% of males, the most common form of color blindness)


The following are some less-common color deficit conditions:

Common Usability Complaints for Colorblind Individuals

The following are some common usability complaints among those who are colorblind:

Design Patterns for Users with Color Deficits

Design patterns to design around users with a color deficit (e.g., colorblindness) are available at ( These are heavily focused on infographics, but the principles are easy to follow.

Discussion of being a colorblind designer, and tips for design:

Color Deficit Simulators

Here is a list of color deficit simulators, which I haven't updated for a couple years so some are likely dead, and it is missing most of the new breed of browser plugins and so on:

Other Color Deficit Design Tools & Resources

Next: Other Mobile Pattern Libraries

Discuss & Add

Please do not change content above this line, as it's a perfect match with the printed book. Everything else you want to add goes down here.


If you want to add examples (and we occasionally do also) add them here.

Other References

Color Deficit Design Tools (last edited 2019-06-26 19:52:42 by shoobe01)