Checking brand palette for color blindness
How many people this really affects
The most common type of impairment is deuteranopia and deuteranomaly, weakness or complete absence of green perception. 5–6,5% of men are affected by this, making the red-green axis a priority zone for checking any palette. Protanopia (red blindness) and tritanopia (blue vision problems) occur much less frequently, but they cannot be completely ignored — especially if blue is used as the primary color in the brand identity, which is typical for brands.
The logic of the check is simple from here: first run the palette through red-green simulations, because they cover the majority of people with color perception impairments, and only then — through blue types.
Problematic color pairs and what to do about them
There are combinations that almost guaranteedly break under any form of color blindness. It is better to know them in advance rather than discover them post facto in user reviews.
| Combination | Why the problem occurs | What to do |
|---|---|---|
| Red + green | Merge under deuteranopia and protanopia | Separate by lightness, not hue; add outline or icon |
| Green + brown | Both groups lose saturation in the gray scale | Make one of the colors significantly lighter/darker |
| Blue + violet | Problem with tritanopia, rarely—but critically important for accents | Increase the difference in brightness by at least 2-3 steps |
| Light green + yellow | Practically indistinguishable under deuteranopia | Do not use as text/background pair, only as decorative accents |
The key principle here is one: people with color vision deficiency rely on luminance rather than hue. If you translate the palette into a black-and-white scale and all elements are still readable — the palette is functional for all types of color vision deficiencies. This is the fastest and crudest test you can perform without a single tool.
WCAG or Delta E: which metric to use
Here competing approaches address different tasks, and confusing them is an error.
| Metric | What it measures | When to apply |
|---|---|---|
| WCAG contrast | The ratio of text and background brightness (requires 4.5:1 for regular text, 3:1 for large text, AA level) | Interfaces with text on a colored background |
| Delta E (CIE2000) | Perceptible difference between two colors under different types of CVD | Checking the palette, logo, and brand elements without text |
Practical rule: Delta E between background and foreground should be at least 10 in all CVD simulations. A value below 2.3 means the human eye does not distinguish the colors at all — this is no longer a question of color vision deficiency, but a defect of the color pair itself. But even if the formal contrast passes, the color should not be the sole carrier of meaning. A red and green button with identical shapes — a bad idea, even if WCAG is formally satisfied. Add icons, text labels, hatching patterns — this is cheaper than repainting the entire system from scratch.
Interface and print — different rules of the game
A common mistake in many guidelines is to check the palette once and assume the result is universal for all media. It is not so.
- Interface: colors are rendered in RGB, screen illumination is stable, contrast can be checked programmatically with automatic tools and adapted through CSS variables without reissuing materials.
- Print: Colors are converted to CMYK or Pantone, perception depends on paper type, room lighting and print quality — Delta E can vary even with a perfect layout. Verification must be done on an actual print, not just on screen preview.
- Outdoor advertising and packaging: distance and external lighting factors are added, due to which small color differences disappear faster than in interfaces — here verification with a large Delta E, not the minimum allowable one, is especially important.
How to fix a fixed palette without rebranding
The most painful question is what to do if the problematic palette is already fixed in the brandbook, applied to signage, and registered as a trademark. A full color replacement is an expensive and often unnecessary solution.
There is room for maneuver here legally: Rospatent allows correction of a trademark color if that color is not stated as a significant element of the trademark protection. That is, in most cases, it is possible to adjust the shade within acceptable limits without re-registering — provided the original application did not specify an exact Pantone as a key feature.
A telling example from rebranding practice is Mail's transition from orange to sage green. The change provided not just a visual update, but measurably higher contrast and better accessibility for users with color vision deficiency. This illustrates the main compromise: it is not necessary to change the entire palette — it is sufficient to adjust one problematic color, while preserving the logo geometry, fonts, and composition of the guidelines.
Procedure for checking in practice
- Run the entire palette through red-green CVD simulations — this covers most cases of color vision deficiency.
- Convert the palette to grayscale and check whether the elements are distinguishable solely by lightness.
- Calculate Delta E between all pairs of 'background — foreground', referencing the minimum 10.
- Check critical text pairs according to WCAG (4.5:1 or 3:1 for large text).
- Check printed samples on a real medium, not only on screen.
- Where color is the only signal, add an icon, pattern, or textual label.
This approach saves time: you can immediately see where a simple cosmetic adjustment of one shade is sufficient, and where you'll need to introduce an additional visual code. And in 90% of cases for an existing brand, this is precisely a localized correction, not a full redesign.
How many people this really affects
The most common type of impairment is deuteranopia and deuteranomaly, weakness or complete absence of green perception. 5–6,5% of men are affected by this, making the red-green axis a priority zone for checking any palette. Protanopia (red blindness) and tritanopia (blue vision problems) occur much less frequently, but they cannot be completely ignored — especially if blue is used as the primary color in the brand identity, which is typical for brands.
The logic of the check is simple from here: first run the palette through red-green simulations, because they cover the majority of people with color perception impairments, and only then — through blue types.
Problematic color pairs and what to do about them
There are combinations that almost guaranteedly break under any form of color blindness. It is better to know them in advance rather than discover them post facto in user reviews.
| Combination | Why the problem occurs | What to do |
|---|---|---|
| Red + green | Merge under deuteranopia and protanopia | Separate by lightness, not hue; add outline or icon |
| Green + brown | Both groups lose saturation in the gray scale | Make one of the colors significantly lighter/darker |
| Blue + violet | Problem with tritanopia, rarely—but critically important for accents | Increase the difference in brightness by at least 2-3 steps |
| Light green + yellow | Practically indistinguishable under deuteranopia | Do not use as text/background pair, only as decorative accents |
The key principle here is one: people with color vision deficiency rely on luminance rather than hue. If you translate the palette into a black-and-white scale and all elements are still readable — the palette is functional for all types of color vision deficiencies. This is the fastest and crudest test you can perform without a single tool.
WCAG or Delta E: which metric to use
Here competing approaches address different tasks, and confusing them is an error.
| Metric | What it measures | When to apply |
|---|---|---|
| WCAG contrast | The ratio of text and background brightness (requires 4.5:1 for regular text, 3:1 for large text, AA level) | Interfaces with text on a colored background |
| Delta E (CIE2000) | Perceptible difference between two colors under different types of CVD | Checking the palette, logo, and brand elements without text |
Practical rule: Delta E between background and foreground should be at least 10 in all CVD simulations. A value below 2.3 means the human eye does not distinguish the colors at all — this is no longer a question of color vision deficiency, but a defect of the color pair itself. But even if the formal contrast passes, the color should not be the sole carrier of meaning. A red and green button with identical shapes — a bad idea, even if WCAG is formally satisfied. Add icons, text labels, hatching patterns — this is cheaper than repainting the entire system from scratch.
Interface and print — different rules of the game
A common mistake in many guidelines is to check the palette once and assume the result is universal for all media. It is not so.
- Interface: colors are rendered in RGB, screen illumination is stable, contrast can be checked programmatically with automatic tools and adapted through CSS variables without reissuing materials.
- Print: Colors are converted to CMYK or Pantone, perception depends on paper type, room lighting and print quality — Delta E can vary even with a perfect layout. Verification must be done on an actual print, not just on screen preview.
- Outdoor advertising and packaging: distance and external lighting factors are added, due to which small color differences disappear faster than in interfaces — here verification with a large Delta E, not the minimum allowable one, is especially important.
How to fix a fixed palette without rebranding
The most painful question is what to do if the problematic palette is already fixed in the brandbook, applied to signage, and registered as a trademark. A full color replacement is an expensive and often unnecessary solution.
There is room for maneuver here legally: Rospatent allows correction of a trademark color if that color is not stated as a significant element of the trademark protection. That is, in most cases, it is possible to adjust the shade within acceptable limits without re-registering — provided the original application did not specify an exact Pantone as a key feature.
A telling example from rebranding practice is Mail's transition from orange to sage green. The change provided not just a visual update, but measurably higher contrast and better accessibility for users with color vision deficiency. This illustrates the main compromise: it is not necessary to change the entire palette — it is sufficient to adjust one problematic color, while preserving the logo geometry, fonts, and composition of the guidelines.
Procedure for checking in practice
- Run the entire palette through red-green CVD simulations — this covers most cases of color vision deficiency.
- Convert the palette to grayscale and check whether the elements are distinguishable solely by lightness.
- Calculate Delta E between all pairs of 'background — foreground', referencing the minimum 10.
- Check critical text pairs according to WCAG (4.5:1 or 3:1 for large text).
- Check printed samples on a real medium, not only on screen.
- Where color is the only signal, add an icon, pattern, or textual label.
This approach saves time: you can immediately see where a simple cosmetic adjustment of one shade is sufficient, and where you'll need to introduce an additional visual code. And in 90% of cases for an existing brand, this is precisely a localized correction, not a full redesign.
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