Duck Code
ColourTrainer app icon, showing a white duck holding a painter's palette

ColourTrainer Available

Train your eye. Grow your colour vocabulary.

A simple and fun way to practise identifying colours, compare the differences between them, and learn a few useful things along the way.

ColourTrainer is an educational game. It is not a vision test, diagnosis, treatment, display-calibration tool, or evidence that your eyesight has changed.

Download on theApp Store Join beta onTestFlight
The trainer Colour of the Day The research Data sources Send feedback
Tone Specialist Which tile is different?
Now available on the App Store Download ColourTrainer for iPhone from Apple’s App Store.

Learn by playing

Short challenges that make you look twice.

ColourTrainer turns colour comparison and vocabulary into relaxed five-to-eight-minute sessions. Difficulty adapts within the game, and “I cannot tell” is always a valid answer.

Spectrum Explorer

Find the family

Explore neighbouring colour families, notice where one seems to become another, and reveal descriptive vocabulary after each choice.

Tone Specialist

Spot the difference

Pick the odd tile while the game changes one controlled quality at a time: hue, lightness, or chroma.

Colour in Motion

Practise amid real-world noise

Build towards familiar colour tasks in increasingly lively scenes, without treating decorative artwork as a colour reference.

Why practise colour?

Colour is something the visual system can learn about.

The research supports a modest idea: repeated, specific practice can change performance on colour tasks, and learning names can shape how adults categorise what they see. It does not show that a phone game can clinically improve eyesight.

01

Practise fine differences

A 2024 study found lower colour-discrimination thresholds after five days of repeated practice. The effects were strongest around trained colours, and the authors also observed shifts in colour appearance and category boundaries.

Read the Scientific Reports study
02

Learn useful distinctions

Adults trained on newly named green and blue subcategories learned the labels quickly; behavioural and brain-imaging results showed that category learning can influence colour processing.

Read the PNAS study
03

Build vocabulary and attention

Putting words to lightness, chroma, hue, and neighbouring families gives you a repeatable way to compare colours—useful for conversation, art, design, shopping, nature, and simple curiosity.

This is a practical inference from discrimination and category-learning research, not a promised outcome.
What “training” means here

It means practising a task and learning language for it. Improvements may be specific to the trained colours, task, display, or viewing context. ColourTrainer reports performance only inside the trainer.

Including colour-vision deficiency

Practice can support strategies; it cannot replace cone function.

People with colour-vision deficiency may still enjoy the vocabulary, comparison, and self-paced practice. Research reports that dichromatic observers can often name colours accurately by learning subtle visual cues and shared language, even when particular hues remain difficult to discriminate.

That can make training useful as practice in noticing available cues and learning labels. It is not a cure, treatment, screening tool, or promise of normal colour vision.

Learned cues and naming A Visual Neuroscience study describes accurate naming supported by subtle cues and a learned language system. Clinical boundary The US National Eye Institute explains that inherited colour-vision deficiency has no cure, though most people adjust to it.
Accessible by design “I cannot tell” is valid, everyday display settings remain supported, and progress should never depend on disabling accessibility preferences.

Sources, standards, and naming

Reference data is useful—not universal truth.

ColourTrainer uses published technical references to generate reproducible on-screen exercises. Those references do not make a phone a calibrated instrument or settle what every person should call a colour.

Data referenceW3C CSS Color Module Level 4

The app uses a 23 July 2026 snapshot of the CSS named-colour table for stable English identifiers and exact sRGB samples. W3C does not define ColourTrainer’s family boundaries, curriculum, descriptions, or cultural meanings.

W3C named colours
Colour mathsOKLab, OKLCH, sRGB, and CIEDE2000

Challenges are authored in OKLCH, converted to tested sRGB output, and may use CIEDE2000 to describe a displayed pair. Numeric distance guides generation; it does not guarantee identical perception.

OKLab reference
Display guidanceApple support documentation

Guidance about colour-changing display settings draws on Apple’s descriptions of Night Shift and Colour Filters. The app cannot infer every display, accessibility, lighting, or environmental condition.

Night ShiftColour Filters
Naming researchWorld Color Survey

Large cross-language studies find shared motifs as well as real diversity within and between languages. Colour names and boundaries can vary with language, community, culture, and individual experience.

Read the PNAS study

Material copied from or derived from CSS Color Module Level 4 is copyright © 2026 World Wide Web Consortium and used under the W3C Software and Document Notice and License.

Availability

Available on the App Store.

Download from the App Store Get the current public release of ColourTrainer for iPhone. Join TestFlight Open Apple’s TestFlight invitation to try preview builds of ColourTrainer. Send feedback Share a suggestion, accessibility concern, source correction, or problem with the app.

Important notes

Colour depends on more than the pixels.

Not a medical or diagnostic tool Do not use ColourTrainer to diagnose, screen, treat, or measure colour-vision deficiency. Ask an optometrist or other qualified professional about vision concerns.
Screens are not reality A colour emitted by a screen is not the same physical stimulus as paint, fabric, food, skin, plants, or another real object under changing light.
Displays and rooms differ Panel hardware, gamut, brightness, viewing angle, screen protectors, ambient light, glare, Night Shift, True Tone, and accessibility settings can change appearance.
Names and boundaries differ W3C names are technical English references. People, languages, and cultures may group and name the same continuum differently—and no hard boundary is perfect for everyone.
People and moments differ Colour perception varies between observers and can also be affected by adaptation, fatigue, comfort, and viewing context.
Preview builds may change TestFlight builds can include unfinished exercises, wording, data, artwork, or availability changes before they reach the App Store release.

Help and policies

Privacy and support

Read how ColourTrainer handles data, or find help with the app, purchases, reminders, widgets, and supporter wallpapers.

Privacy policy Help and support