color
Let an agent specify colour precisely with a colour space or system, and handle the gap between physical light, perception, names and device reproduction.
Research draft, second pass
A second pass drafted this model: the structure a model of this thing needs, and what is known about it in the world. The line under this one says how the second half was obtained - researched against sources, or recalled without web access, in which case nothing here was read anywhere and every claim is a lead to verify. Unreviewed either way.
written by Claude from model knowledge without web access - no source was read, every claim is a lead to verify
Researched by: Claude
Purpose and description
Let an agent specify colour precisely with a colour space or system, and handle the gap between physical light, perception, names and device reproduction.
The property of light, and of objects that reflect or emit it, perceived as hue, saturation and lightness, arising from the spectral distribution of light and the response of the eye and brain.
What it is for: Describing, matching and reproducing appearance, in design, printing, screens, paint, signals and science.
It can be measure it, with spectrophotometers and colorimeters; specify it, in colour spaces or systems; reproduce it, on screens, in print or with pigments; name it, which is imprecise and language-dependent.
Distinguishing features
Partly physical, partly perceptual
Specified in colour spaces with defined illuminants
Device-dependent values (RGB, CMYK) differ from device-independent ones (CIELAB)
Colour vision deficiency changes what people see
What it looks like
Everything seen has colour; the same object looks different under different light.
Physical character
visible wavelengths: 380-750 nm
colour difference noticeable: about 1-2 Delta E - CIEDE2000
How it is recognised
Colour names are approximate and cultural
Codes such as hex #RRGGBB, Pantone numbers or CIELAB values specify colour
Appearance depends on the light source and surroundings
Related models
has kind - individual colours are entries
is produced by - materials and emission
is perceived by - depends on the observer
is used in - safety colours, brands
In practice
Families and kinds
colour spaces: sRGB, CIELAB, CMYK
colour systems: Munsell, Pantone, RAL, NCS
pigments and dyes
web colours and web-safe colours
colour names
Identifiers
hex code #RRGGBB in sRGB web colours
Pantone number for example Pantone 179 C proprietary spot colours
RAL code four digits industrial colours
Standards and regulation
CIE colorimetry standards
IEC 61966-2-1 sRGB
ISO 3864 safety colours
WCAG contrast requirements
Failure modes and hazards
Colour mismatch between screen and print
Relying on colour alone, excluding colour-blind users
Poor contrast making text unreadable
Toxic historical pigments such as cadmium and lead
Also called
+136
Where this came from
wikidata · CC0 1.0
Also registered as vr.tr.color-2
Drafted structure
Bundle to layer to finding to question, as the second pass will find it: 4 bundles · 8 layers · 8 findings · 16 questions.
Specification Stating a colour precisely.
Without a colour space and illuminant, a colour value is ambiguous.
Colour space
sRGB, CIELAB, CMYK.
Colour space
The space and values.
- In which colour space is this colour given, and with what values? measurement
- Which illuminant and observer apply? provenance
Colour system
Pantone, RAL, Munsell.
System reference
The system reference.
- Which colour system code specifies it? provenance
- What is its closest sRGB equivalent? measurement
Perception How it is seen.
The same colour looks different to different people and in different light.
Viewing conditions
Light and surround.
Viewing conditions
Lighting and background.
- Under which light and against what background is it seen? definition
- How much does its appearance shift? measurement
Accessibility
Colour vision and contrast.
Accessibility
Contrast and colour-blind safety.
- Does the design rely on colour alone? boundary
- Does it meet contrast requirements? measurement
Reproduction Screens, print, paint.
Each medium has its own gamut and limits.
Gamut
What a device can show.
Gamut check
Whether the colour fits the gamut.
- Can this colour be reproduced in the target medium? boundary
- How will it be mapped if not? action
Matching
Colour difference.
Match tolerance
Tolerance for matches.
- What colour difference is acceptable? measurement
- How is the match verified? action
Meaning and materials What colour signals and what makes it.
Colours carry meaning and come from materials with risks.
Meaning
Safety and cultural meanings.
Meaning
Conventional meanings.
- Which safety or cultural meaning does this colour carry here? definition
- Could it be misread in another culture? boundary
Pigments
Materials and toxicity.
Pigment
Pigments used.
- Which pigment or dye produces it? definition
- Is that material hazardous? boundary
What the second pass must settle
- Which colour space should the registry use as reference?
- How should colour names across languages be linked?
- Should pigments be separate entries from colours?