# colorcurio.us > colorcurio.us — a directory of color tools, resources, and curios. A colormap browser with OKLCh perceptual diagnostics for 386 colormaps, an editorially curated library of 225 color resources, and four in-house tools. The library is editorial, not algorithmic — an entry earns its place if it can be described in a sentence that makes a small claim. The colormap browser measures every map perceptually in OKLCh: lightness, chroma, hue, ΔE uniformity, and colorblind safety. Every page has a Markdown version at `/ai/.md` (the home page is `/ai/index.md`); pages link to it with ``. ## Sections - [Home](https://colorcurio.us/ai/index.md): site overview - [Colormaps](https://colorcurio.us/ai/colormaps.md): 386 colormaps with OKLCh perceptual diagnostics - [Colormap families](https://colorcurio.us/ai/colormaps/families.md): browse by source collection (16 families) - [Compare colormaps](https://colorcurio.us/ai/colormaps/compare.md): side-by-side OKLCh profile comparison - [Library](https://colorcurio.us/ai/library.md): hand-curated directory of 225 color resources - [Library collections](https://colorcurio.us/ai/library/collections.md): thematic reading paths through the library - [Tools](https://colorcurio.us/ai/tools.md): four in-house applets: Picker, Gradient, Extract, Vectorscope - [Notes](https://colorcurio.us/ai/notes.md): illustrated long-form writing on color - [About](https://colorcurio.us/ai/about.md): what the site is and how it is curated ## Tools - [Picker](https://colorcurio.us/tools/picker): OKHSL picker with gamut indicators - [Gradient](https://colorcurio.us/tools/gradient): multi-stop gradient editor with perceptual diagnostics and exports - [Extract](https://colorcurio.us/tools/extract): lift a clean colormap from a legend strip, or extract a palette from any image - [Vectorscope](https://colorcurio.us/tools/vectorscope): plot any palette or colormap on the OKLCh chroma/hue plane ## Notes - [Anatomy of a colormap](https://colorcurio.us/ai/notes/anatomy-of-a-colormap.md): A scroll-driven teardown of every component that makes a colormap useful — anchor stops, oklab mixing, the load-bearing lightness axis, diverging midpoints, and the grayscale test. - [How sharp should the pivot be?](https://colorcurio.us/ai/notes/diverging-pivot-sharpness.md): Diverging colormaps pivot around a center — but how abruptly? A scroll-driven look at pivot sharpness, a county map you can sharpen by hand, why an asymmetric domain still wants a symmetric scale, and a comparison of how smoothly common diverging maps turn at the pivot. ## Collections - [Cartography Essentials](https://colorcurio.us/ai/library/collections/cartography-essentials.md): If you make maps, these are the entries to know about. The list leans toward palettes engineered for terrain, bathymetry, and choropleths… - [Colorblind-Safe Workflows](https://colorcurio.us/ai/library/collections/colorblind-safe-workflows.md): Most accessibility work focuses on text contrast, which is the easy half of the problem. These entries are about the harder half: making… - [Foundational Reading](https://colorcurio.us/ai/library/collections/foundational-reading.md): The papers and books the rest of the library keeps quoting, in roughly the order they are worth reading. Albers teaches you to distrust a… - [The OKLCh Ecosystem](https://colorcurio.us/ai/library/collections/oklch-ecosystem.md): OKLCh is the color space that quietly turned color tooling honest: perceptual uniformity that holds up across hues, predictable mixing, and… - [Perceptual Colormaps](https://colorcurio.us/ai/library/collections/perceptual-colormaps.md): How science got off jet. Borland and Taylor diagnosed the problem, Dave Green's cubehelix and Moreland's cool-warm offered early fixes, and… - [Weekend Rabbit Holes](https://colorcurio.us/ai/library/collections/weekend-rabbit-holes.md): Long, strange, and worth it. These are the entries you open on a Saturday morning and look up from at dusk: Bartosz Ciechanowski's… ## Featured Library Resources - [OKLCH in CSS: Why We Moved from RGB and HSL](https://evilmartians.com/chronicles/oklch-in-css-why-quit-rgb-hsl): by Andrey Sitnik. The case for OKLCH in CSS: lightness that holds across hues, and the syntax to replace RGB and HSL. (annotation: https://colorcurio.us/library/oklch-in-css) - [Color.js](https://colorjs.io/): by Lea Verou & Chris Lilley. A JS library for the CSS Color specs: convert, interpolate, and gamut-map across OKLab, OKLCH, P3, and more. (annotation: https://colorcurio.us/library/colorjs) - [ColorBrewer 2.0](https://colorbrewer2.org/): by Cynthia Brewer. Map color schemes filtered by class count, scheme type, print safety, and colorblind safety. (annotation: https://colorcurio.us/library/colorbrewer) - [Culori](https://culorijs.org/): by Dan Burzo. A functional JS color library for converting, interpolating, and measuring difference across many spaces. (annotation: https://colorcurio.us/library/culori) - [A Perceptual Color Space for Image Processing](https://bottosson.github.io/posts/oklab/): by Björn Ottosson. The post introducing OKLab: where CIELAB’s hue and lightness slip, and the transform that fixes them. (annotation: https://colorcurio.us/library/oklab-color-space) - [Leonardo Color](https://leonardocolor.io/): by Nate Baldwin. Generate UI ramps from a key color so chosen steps hit target contrast ratios against a background. (annotation: https://colorcurio.us/library/leonardo) - [Subtleties of Color](https://science.nasa.gov/blogs/earth-matters/2013/08/05/subtleties-of-color-part-1-of-6/): by Robert Simmon. A six-part NASA series on encoding earth-observation data in color, from rainbow defaults to diverging schemes. (annotation: https://colorcurio.us/library/subtleties-of-color) - [Datawrapper: color in data vis](https://www.datawrapper.de/blog/category/color-in-data-vis): by Lisa Charlotte Muth. Every Datawrapper blog post on color in data visualization, in one list. (annotation: https://colorcurio.us/library/datawrapper-posts) - [Scientific Colour Maps](https://www.fabiocrameri.ch/colourmaps/): by Fabio Crameri. Perceptually uniform, colorblind-friendly maps such as batlow and vik, built to replace rainbow scales. (annotation: https://colorcurio.us/library/scientific-colour-maps) - [cmocean](https://matplotlib.org/cmocean/): by Kristen Thyng. Oceanography colormaps — thermal, haline, dense, and more — each matched to the variable it encodes. (annotation: https://colorcurio.us/library/cmocean) - [OKLCH Color Picker](https://oklch.com/): by Evil Martians. Pick colors in OKLCH on the same axes as the CSS function, with sRGB and P3 gamut warnings. (annotation: https://colorcurio.us/library/oklch-picker) - [Phosphor](https://www.joshuastevens.net/phosphor/): by Joshua Stevens. Turn a few hexes into a ramp whose lightness climbs evenly in OKLab, with CVD previews. (annotation: https://colorcurio.us/library/phosphor) - [Color Universal Design (CUD)](https://jfly.uni-koeln.de/color/): by Masataka Okabe & Kei Ito. A guide to figures that survive color-vision deficiency, and the source of the eight-color Okabe–Ito palette. (annotation: https://colorcurio.us/library/okabe-ito-cud) - [A Better Default Colormap for Matplotlib](https://www.youtube.com/watch?v=xAoljeRJ3lU): by Nathaniel Smith & Stéfan van der Walt. The SciPy 2015 talk: the case against jet, and how viridis was designed in CAM02-UCS. (annotation: https://colorcurio.us/library/scipy-viridis-talk) - [Interaction of Color](https://interactionofcolor.com/): by Josef Albers. Albers’ course in seeing color relatively, in Yale’s complete digital edition with interactive plates. (annotation: https://colorcurio.us/library/interaction-of-color) - [Mapping Color to Meaning in Colormap Data Visualizations](https://schlosslab.discovery.wisc.edu/wp-content/uploads/2018/09/SchlossGramazioSilvermanParkerWanginPress.pdf): by Karen B. Schloss, Connor C. Gramazio, A. Taylor Silverman, Madeline L. Parker & Audrey S. Wang. Viewers read darker as more — unless a map looks semi-transparent, and then more opaque reads as more. (annotation: https://colorcurio.us/library/mapping-color-to-meaning) - [Coloring for Colorblindness](https://davidmathlogic.com/colorblind/): by David Nichols. Edit swatches and see them as protan, deutan, and tritan viewers would, with Wong, IBM, and Tol sets preloaded. (annotation: https://colorcurio.us/library/coloring-for-colorblindness) - [Is My Blue Your Blue?](https://ismy.blue/): by Patrick Mineault. Call a run of hues blue or green to find your boundary, then see how it compares with everyone else’s. (annotation: https://colorcurio.us/library/ismy-blue) ## Key Topics - Colormaps and scientific palettes (matplotlib, cmocean, Scientific Colour Maps, CARTOColors, ColorBrewer) - OKLCh and perceptually uniform color spaces - Perceptual uniformity: lightness monotonicity, chroma range, hue path, ΔE step size - Diverging colormaps: pivot design, sharpness, the zero-crossing trade-off - Colorblind safety: protan/deutan/tritan simulation, CVD ΔE - Cartography and data visualization color choices - Color accessibility (WCAG contrast, design systems) - OKLCh gradient interpolation and CSS color tooling ## Optional - [Colormap data](https://colorcurio.us/ai/colormaps.md): index of all 386 per-colormap Markdown files, at https://colorcurio.us/ai/colormaps/.md - [Library entries](https://colorcurio.us/ai/library.md): the full directory; per-entry annotations at https://colorcurio.us/ai/library/.md - [Sitemap](https://colorcurio.us/sitemap.xml): every HTML page