Auric Artisan

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Every article on this site about colour, in the order it was written to be read.

All articles

WCAG vs APCA: which contrast method should you use? — WCAG 2 contrast ratios vs APCA Lc values: how each is calculated, where they disagree, which one the law cites, and how to pick colors that pass both.
How to make your brand color accessible — Why brand colors like gold, orange and cyan fail WCAG contrast, and how to derive accessible text, UI and dark-mode shades that keep the brand's hue.
The Color of Heat: Why Hot Things Glow - Incandescence, Blackbody Radiation, and the Color of Stars — How Planck's law and Wien's displacement law explain why heated things glow red then white then blue - and why the Sun is white. Explored interactively.
Light and the Body Clock: Blue Light, Melanopsin, and Circadian Color — How the color of light sets your body clock - melanopsin, melatonin, color temperature, and night modes, explored with interactive demos.
The Colors of Animals: Camouflage, Warning, and Display — Why animals are colored the way they are - camouflage, warning colors, mimicry, and angle-shifting structural color, explored with interactive demos.
The Families of Printing: Relief, Intaglio, Planographic, and Screen - How Each Lays Down Color — The four families of printing and how each physically lays ink - explored with interactive plate cross-sections, ink-film models, and a process chooser.
The Stories of Famous Pigments: Color's Most Precious, Poisonous, and Peculiar — Behind every color on a canvas is a substance, and some of those substances have wild histories.
Gamut Volume: How Much Color a Wide Gamut Actually Adds — How sRGB, P3, Adobe RGB, and Rec.2020 nest on the chromaticity diagram, how much each covers, and where the extra colors live - explored interactively.
Color in Maps: Elevation Tints, Choropleths, and Shaded Relief — Hypsometric elevation tints, sequential vs diverging choropleths, and shaded relief - how maps use color, explored interactively.
Contrast Sensitivity: The Spatial Frequencies You Can and Can't See — Vision scientists describe detail by spatial frequency : how many light-dark cycles a pattern packs into a degree of your visual field.
E-Ink and Reflective Displays: The Screen That Acts Like Paper — An interactive guide to e-ink and reflective displays: why they read by ambient light like paper, hold an image at zero power, and look muted in color.
Spectral Rendering: Why Three Numbers Aren't Enough - Computing Color the Way Light Really Works — The finale of the color-science library: why realistic color needs full spectra, not three RGB numbers.
Patina, Rust, and Tarnish: How Color Changes as Metal Ages — An interactive guide to how metal changes color as it ages: why copper turns green, iron orange and silver black, and why aluminum stays bright.
Color in Games: Rarity, HUDs, and Playing Without Color — The loot-rarity ladder, HUD status colors, and how games lead colorblind accessibility - color in games, explored interactively.
Densitometry and Press Control: How Printers Measure and Hold Color — Optical density, the color bar, Murray-Davies dot gain, and ink keys - how printers measure and hold color on press, explored interactively.
MacAdam Ellipses: Why the Color Diagram Lies About Distance — Equal distances on the chromaticity diagram do not mean equal color difference. MacAdam ellipses, perceptual uniformity, and the fix - explored interactively.
The Color of Gemstones: Why Ruby Is Red and Sapphire Is Blue — Trace impurities that absorb light, and why the same chromium ion makes ruby red but emerald green - the color of gemstones, explored interactively.
How Displays Make Color: LCD, OLED, and the Subpixel — Every pixel is three tiny lights. How subpixels, backlights, and self-emission make color - and why OLED blacks are truly black, explored interactively.
Color and Sound: Synesthesia, Color Organs, and the One Octave of Light — Color organs, disagreeing pitch-to-color schemes, and the surprising fact that all of color is a single octave of light - explored interactively.
Color in Motion: Flicker Fusion, Spinning Disks, and Benham's Colors — Spinning disks that fuse colors, Newton's disk to gray, and Benham's illusory colors - the color science of time, explored interactively.
Screen Printing: How Posters and T-Shirts Get Their Color — One screen per ink, registration, underbase, and halftones - how screen printing builds color, explored interactively.
Color and Food: Why We Eat with Our Eyes — Why warm foods look appetizing and blue looks wrong, why blue food is rare, and how color sets flavor expectations - explored interactively.
The Color of Metals: Why Gold Is Gold and Silver Is a Mirror — Why gold is yellow and copper red while silver is neutral - an interband absorption edge in the reflectance spectrum. Explored interactively.
Dominant Wavelength and Purity: Naming a Color by Its Spectrum — An interactive guide to dominant wavelength and excitation purity: naming any color as a spectral hue plus a purity, read off the chromaticity diagram.
Chromatic Acuity: Why You See Detail in Brightness, Not Color — The eye resolves fine detail in brightness but blurs color - which is why video and JPEG throw away most color data invisibly. Explored interactively.
Security Printing: The Color Tricks That Stop Counterfeits — Color-shifting inks, UV-fluorescent features, and microprinting - the color science that separates real banknotes from fakes, explored interactively.
Grayscale: The Many Ways to Remove Color — There is no single 'grayscale' - there are many, and they disagree. Luminosity, average, lightness, channels, and gamma, explored interactively.
Color Rendering: Why Two "White" Lights Reveal Colors Differently — Two lights can both look white yet render the same object completely differently. The science of color rendering and CRI, interactively.
Color Trends and Forecasting: How a Color of the Year Is Chosen — A quarter-century of Colors of the Year, how a trend rises and fades, seasonal palette building, and runway-to-retail toning - color forecasting, interactively.
Optical Mixing and Pointillism: The Third Kind of Color Mixing — You know two ways to mix color: add beams of light and they brighten; overlap paints or filters and they darken.
The Perception of Transparency: How the Eye Sees Through Things — A pane of tinted glass, a splash of water, a sheet of tracing paper - you see through them instantly, without thinking.
Simultaneous Contrast: Why a Color Depends on Its Neighbors — Pick a color. You have not, in fact, picked how it will look - because the same swatch changes its appearance the moment you put something next to it.
Color in Real-Time 3D: Albedo, PBR, and Tone Mapping — Albedo vs the lit pixel, linear-light shading, energy conservation, and tone mapping HDR to a display - color in real-time 3D, interactively.
Overprint, Trapping, and Registration — How the four plates register, what misregistration does, how trapping hides gaps, overprint vs knockout, and what inks make when they stack - interactively.
Measuring White: Whiteness and Yellowness Indices — The CIE Whiteness index, ASTM Yellowness Index, why bluing makes things measure whiter, and how optical brighteners beat 100 - interactively.
Color at Depth: Why the Underwater World Is Blue — Water is not colorless - it's a very pale blue, and over long distances that faint tint becomes overwhelming.
Color in Wayfinding and Environmental Design — Distinct transit palettes, color-blind confusability, sign legibility at a distance, and redundant coding - color for finding your way, interactively.
The Evolution of Color Vision — The dichromat bottleneck, the primate regain of a third cone, the fruit-finding advantage, and why color blindness is X-linked - interactively.
GCR, UCR, and Ink Limits: Managing the Black Channel — Gray component replacement, under color removal, black generation curves, TAC ink limits, and registration-safe black - CMYK's black channel, interactively.
The Standard Observer: 2° vs 10° and the Average Eye — The color-matching experiment, negative primaries, the 2° vs 10° observers, macular pigment, and observer metamerism - interactively.
Chromatic Aberration and Color Fringing — Why lenses split color: dispersion, longitudinal vs lateral CA, purple and green fringing, and how it's corrected - interactively.
Primary Colors and Color Wheels: Why the Models Disagree — Why there's no single 'true' set of primaries, how RYB, RGB, and perceptual wheels differ, and why complements and mixing disagree - interactively.
Dot Gain and Tone Reproduction on Press — Why printed midtones darken, mechanical vs optical dot gain, the TVI curve, how paper and screen change it, and how compensation fixes it - interactively.
Color Difference in Practice: Tolerances and Pass/Fail QC — An interactive guide to color difference in production: ΔE compared, pass/fail tolerances, perceptibility versus acceptability, and tolerance ellipses.
Memory Color and Preferred Reproduction — An interactive guide to memory color and preferred reproduction: why we remember grass greener and skies bluer, and why displays render to please.
Emission: Neon, LEDs, and Gas-Discharge Light — Emission line spectra, neon and sodium tubes, the blue-pump-plus-phosphor white LED, and why a source's spectrum decides how colors render - interactively.
Color Grading and LUTs — Lift/gamma/gain, the teal-and-orange look, 3D lookup tables and trilinear interpolation, and why colorists grade in log - color grading, interactively.
Skin Tones and Inclusive Color — An interactive guide to skin color and inclusive design: melanin and hemoglobin, the Fitzpatrick and Monk scales, the ITA metric, and camera bias.
Color Quantization and Dithering — An interactive guide to color quantization and dithering: posterization and banding, choosing a palette, and ordered (Bayer) and Floyd-Steinberg dithering.
Color in CSS: Modern Color in the Browser — color-mix(), relative color syntax, the color() function, oklch(), wide-gamut Display-P3, and browser gamut mapping - modern CSS color, interactively.
Black, White, and Gray: The Achromatic Colors — Perceptual lightness versus linear, the myth of middle gray, why black and white are relative, tinted neutrals, and using neutrals as the backbone of design.
Tetrachromacy, Anomalous Trichromacy, and the Range of Human Color Vision — A deep, interactive guide to variation in human color vision: anomalous trichromacy, potential tetrachromacy, cone-ratio differences, and unique hues.
Color in Typography and Text: Readable, Accessible, Beautiful — Readable body-text contrast, why pure black is harsh, the risk of colored text, link cues, and legible code themes - text color, explained interactively.
Diffraction and Diffraction Gratings: The CD Rainbow — Why a CD throws a rainbow, how a grating splits white light by wavelength, the grating equation, orders, and grating vs prism - explained interactively.
White Points and Chromatic Adaptation: von Kries, Bradford, and CAT02 — A deep, interactive guide to white points and chromatic adaptation transforms: reference whites (D50, D65, A), the von Kries model, Bradford, and CAT02.
Color on Textiles: Dyeing, Printing, and Why Fabric Color Is Hard — A deep, interactive guide to color on textiles: dyeing versus pigment printing, how fiber type changes color uptake, and wash, light, and rub fastness.
Digital Printing: Inkjet, Toner, and How They Differ from Offset — How inkjet droplets, fused toner, offset rosettes, and dye-sub continuous tone each make color - and when digital beats offset. Explained interactively.
Lightfastness and Fade: Why Colors Fade and How to Make Them Last — A deep, interactive guide to lightfastness and fading: why pigments fade, the Blue Wool and ASTM scales, what speeds fading, and how to make color last.
Color Vision Across the Lifespan: Development, Aging, and the Yellowing Lens — Why a newborn sees little color, why the lens yellows with age, and why older eyes lose blues and need more light - color vision over a lifetime, interactively.
The Color Solid: Visualizing All Colors in Three Dimensions — Color needs three numbers, so all colors form a solid. Spin the RGB cube, the HSL cylinder, the Lab solid, and see why real gamuts taper - interactively.
Semantic Color: Status, States, and Feedback in UI — Success, warning, error, info; hover, active, disabled, focus; and why color must never be the only signal - semantic UI color, explained interactively.
Thin-Film Interference and Iridescence — Why a soap bubble blooms with color and shifts as you tilt it - the wave interference behind iridescence and structural color, explained interactively.
Warm and Cool Colors: The Temperature of Color — Why oranges feel warm and blues feel cool, why warm colors come forward, and how warmth is always relative - the temperature of color, explained interactively.
Afterimages and the Opponent Process: Why Colors Leave Ghosts — A deep, interactive guide to color afterimages: negative and positive afterimages, the opponent-process theory behind them, and receptor adaptation.
Color Proofing: Soft Proofing and Hard Proofs — A deep, interactive guide to color proofing: soft proofs, paper-white and black-point simulation, gamut warnings, rendering intents, and contract proofs.
Polarization and Color — A deep, interactive guide to how polarization makes and reveals color: Malus's law, photoelastic stress colors, the polarized sky, and how LCDs work.
The Vocabulary of Color: Hue, Saturation, Value, Tint, Tone, and Shade — Hue, saturation, chroma, lightness, value, tint, tone, shade - the precise meaning of every color word, explained interactively.
Fluorescence, Phosphorescence, and Optical Brighteners — Why a highlighter glows, why your white shirt is secretly blue, and why glow-in-the-dark stars fade slowly - luminescence in color, explained interactively.
Vision in Dim Light: Rods, Scotopic Vision, and the Purkinje Shift — A deep, interactive guide to low-light color vision: rods vs cones, scotopic vision, the Purkinje shift, dark adaptation, and averted vision.
Spot Colors, Duotones, and Specialty Inks — When CMYK is not enough: spot inks for exact color, duotones, metallics, fluorescents, varnish, and white ink on colored stock - explained interactively.
Additive and Subtractive Color Mixing — Why lights add to white and inks subtract to black: the two great models of color mixing, plus partitive optical mixing - explained interactively.
Halftones and Screening: How Print Turns Color into Dots — An interactive guide to halftoning - line screen, screen angles, AM vs FM screening, dot gain, rosettes, and moire in CMYK printing.
Color in Branding and Identity — How brands choose a distinctive, ownable color, keep it consistent across screen and print, and survive the one-color test - explained interactively.
Camera Color — An interactive guide to the camera color pipeline - the Bayer array, demosaicing, white balance, the color matrix and profiles, and raw vs JPEG.
Color Appearance Models — The same color looks different in dim vs bright light, on a dark vs light surround. Appearance models like CIECAM predict that - here is how, interactively.
Color in Nature — The physics behind the blue sky, red sunsets, rainbows, and white clouds - scattering, refraction, and atmospheric color, explained interactively.
Color in Film and Video — Why raw footage looks flat, what a LUT really is, how lift/gamma/gain grades an image, and how color flows from camera to delivery - explained interactively.
Color Naming and Categorical Perception — Where does green become blue? Languages carve the spectrum differently, and the words we have subtly shape what we see - explained interactively.
Gamut Mapping — An interactive guide to gamut mapping - in vs out of gamut, clipping vs compression, the four ICC rendering intents, and why naive clipping shifts hue.
Building a Color System — Picking a few colors you like is the easy part - and it does not scale.
Bit Depth, Channels, and Alpha — Under every color you have read about in this library is a far less glamorous truth: in a file, a color is just a handful of numbers.
Animal and Non-Human Color Vision — An interactive guide to comparative color vision - dichromats, trichromats, tetrachromats, UV vision, the mantis shrimp, and how ecology shapes color vision.
How Colorants Work — The other articles here ask how we see color and how screens and presses reproduce it. This one asks the older question: why does a thing have a color at all?
Substrates and Finishing — On a screen, the brightest a color can be is the backlight. In print, the brightest a color can be is the paper - and paper is never pure white.
Dark Mode and Adaptive Color — The tempting shortcut is to invert every color - swap light for dark and call it done. It fails immediately.
Color Illusions and the Limits of Perception — Color is inferred, not read. Explore afterimages, contrast, assimilation, constancy, and a combined perception model interactively.
Color Order Systems: Munsell, NCS, Pantone, and RAL — A deep, interactive guide to color order systems: Munsell hue/value/chroma, the Natural Color System (NCS), Pantone spot colors, and RAL.
Color Temperature and White Balance — A deep, interactive guide to color temperature and white balance: the Kelvin scale, why high Kelvin looks cool, CCT and tint, and mireds.
Color Gradients and Interpolation — An advanced, interactive guide to gradient interpolation spaces, hue paths, gamma correction, banding, dithering, and production CSS.
Color Psychology and the Meaning of Color — What colors mean, where those meanings come from, how they change across cultures, and how brands use them - explained interactively, with the myths debunked.
Color in Data Visualization — A deep, interactive guide to color in data visualization: sequential, diverging, and categorical scales, why the rainbow (jet) misleads, and CVD-safe palettes.
Color Theory and Harmony — A deep, interactive guide to color theory and harmony: the color wheel, tints, shades and tones, warm and cool color, and the seven harmony schemes.
CMYK and the Four-Color Printing Process — Why ink mixes the opposite way to light, where the black plate comes from, how halftones fake continuous tone, and why your screen colors shrink on paper.
Oklab and Oklch: Modern Perceptual Color Spaces — The perceptual color space behind modern CSS - why equal steps finally look equal, how the math works, and when to reach for oklch() over HSL or CIELAB.
HSL, HSV, and HSB: The Cylindrical Color Models — Why designers reach for HSL and HSV instead of RGB, what separates lightness from value, the conversion math, and where the cylinder models break down.
ΔE Metrics from CIE76 to CIEDE2000 and ΔEITP — Every color difference formula in active use, what they correct, where they fail, and which one to use for which job.
Accessible Color Design and WCAG Contrast — The contrast standards, the math behind them, the cases they get wrong, and the modern alternatives - with interactive testers.
Spectrophotometers, Colorimeters, and Spectroradiometers — The three families of color measurement instruments, their geometries, their accuracy classes, and how to choose between them.
RGB, sRGB, Adobe RGB, ProPhoto, Display P3, and Rec.2020 — The seven RGB spaces that dominate digital imaging, with primaries, white points, transfer functions, and conversion matrices interactively laid bare.
Metamerism Explained — How two very different spectra can produce the same color - and break apart under a different light or observer.
ICC Profiles and How Color Management Actually Works — What ICC profiles are, how they're structured, the four rendering intents, and why color management is the bridge between every device and every other device.
How to Calibrate and Profile a Display — From sensor on the screen to a usable ICC profile - the full procedure, the tradeoffs, and the discipline that keeps the result honest.
HDR, Wide Gamut, PQ, HLG, and Modern Displays — What HDR actually is, the curves that encode it, the formats that deliver it, and the displays that finally show it.
Gamma, Linear Light, and Transfer Functions — The curves that connect file values to display luminance, why they exist, and how to use them correctly in compositing, blending, and HDR.
End-to-End Color Management Workflow — The full pipeline from sensor to destination, with the discipline that keeps color predictable at every handoff.
Spectral Power Distributions and Why RGB Is Not Enough — A deep, interactive guide to spectral power distributions: standard illuminants (D65, D50, A, F2, LED), metamerism, CRI, and why RGB is not enough.
The Physics of Light, Wavelength, and Spectrum — A deep, interactive guide to the physics of light: the EM spectrum, photon energy, blackbody radiation, refraction, scattering, and photometry.
Human Color Vision: Cones, Opponent Signals, and the Brain — A deep, interactive guide to human color vision: retinal layers, phototransduction, the cone mosaic, ganglion cells, LGN pathways, V1, and V4.
The History of Color Science from Newton to Hering — A deep, interactive history of color science: Aristotle and Alhazen, Newton's prism, Goethe, Young, Maxwell, Hering, and the CIE 1931 standard.
Color Constancy, Adaptation, and Why Colors Change with Context — An interactive deep-dive into how the brain holds object color stable across illuminants - and how it fails.
Color Blindness and Color Vision Deficiency — An interactive guide to the biology, testing, simulation, and design implications of color vision deficiency.
CIELAB and LCH Explained — The perceptually scaled color space at the heart of modern tolerancing, palette design, and ΔE - explained with live demos.
CIE XYZ Explained — The central reference of modern color science: how XYZ was built, what the matching functions mean, and why every other color space depends on it.
Chromaticity Diagrams Without the Intimidation — The horseshoe, the line of purples, gamut triangles, white points, CCT, and dominant wavelength - explained with live demos.
What Color Is and How Humans See It — An interactive, comprehensive guide to color: the physics of light, the biology of vision, trichromatic and opponent theories, and color standards.

Shorter notes on what is being built are on the blog, and release detail is in the changelog.