Protan and deutan
Two groups within red-green colour vision deficiency. They affect different cone-cell signals. Neither means every red and green look the same, and other colours can be involved too.
Red-green guideColour blindness
Colour blindness usually means some colours are hard to tell apart. A black-and-white world is rare. Compare the main types, then see what makes everyday information easier to read.
The unfiltered board stays on the left. The second board uses your chosen model. Try switching off the extra clues, then bring them back.
Unfiltered reference
A fictional travel board
ARiversideCancelled
BTown centreOn time
CRail stationDelayed
Colour is a useful clue. Words and shapes add another.
Deutan colour model
A fictional travel board
ARiversideCancelled
BTown centreOn time
CRail stationDelayed
Colour is a useful clue. Words and shapes add another.
Colour boards hidden. The written example below explains the same idea.
Three messages, more than one clue
The words say Riverside is cancelled, Town centre is on time and Rail station is delayed. The shapes give another way to tell them apart. Both clues keep working when the colours change.
What the names mean
Tritan
The blue-yellow group. Some colour relationships change differently from the red-green examples. A new change in colour vision needs checking, even when mild.
Blue-yellow guideAchromatopsia
A separate, rare inherited condition. Colour vision is limited, detail is reduced and bright light is uncomfortable. Not the same as common red-green colour blindness.
Achromatopsia guideSmall changes, clearer information
School worksheets
Colour can carry an answer a child cannot reliably tell apart.
What may help
Add written colour names and patterns, and tell the teacher about the diagnosis.
Charts and travel maps
A line may be hard to follow when its colour is the only clue.
What may help
Use route names, symbols and direct labels.
Clothes and shopping
Matching shades can take extra checking.
What may help
Keep colour names on labels or ask for confirmation when the shade matters.
Inherited retinal conditions
Achromatopsia
An inherited condition which makes colours and fine detail hard to see. Bright light is often uncomfortable.
Colour vision
Colour vision deficiency
Some colours are harder to tell apart. Most people still see colour. Different types affect different colour pairs.
Colour vision
Red-green colour vision deficiency
The commonest group of inherited colour-vision differences. More colour pairs are affected than the name suggests.
Colour vision
Blue-yellow colour vision deficiency
A less common colour-vision difference, sometimes called a tritan type. Some people are born with the difference and others acquire the change later.
How these colour examples work
The examples use the published colour-shift matrices from Machado, Oliveira and Fernandes (2009), applied in linear RGB. The blue-yellow example is an approximation. Your screen, your surroundings and your own sight all affect what you see. These boards are not a colour-vision test and do not match everyone's perception.
The explorer's blend slider mixes a model with the original image. The slider is not a medical severity scale. The studio uses the fixed published matrices.