Guide
Finding Schemes
Learn how to search, filter, and discover color schemes programmatically.
Finding Schemes in ColorSchemes
color-schemes-js provides the function getInverse(cscheme, color), which is the inverse of get(cscheme, t). Given an RGB color value, this function evaluates the scheme and returns a normalized value between 0.0 and 1.0 corresponding to the closest matching position along the scheme's axis.
import { getInverse, colorschemes } from 'color-schemes-js';
const targetColor = { r: 120, g: 40, b: 180 };
const normalizedPosition = getInverse(colorschemes.viridis, targetColor);
// => returns position e.g. 0.42
Practical Example: Heatmap Data Extraction
One practical application for getInverse() is reconstructing continuous scalar data values (such as temperature, elevation, or concentration) from image pixel data when raw numerical values are unavailable.
import { getInverse, colorschemes } from 'color-schemes-js';
// Process array of pixel color data from a canvas or image context
function extractDataFromHeatmap(pixelArray, width, height) {
const values = new Float64Array(width * height);
for (let i = 0; i < pixelArray.length; i += 4) {
const pixel = {
r: pixelArray[i],
g: pixelArray[i + 1],
b: pixelArray[i + 2]
};
// Map pixel back to continuous value [0.0, 1.0]
const pixelIndex = i / 4;
values[pixelIndex] = getInverse(colorschemes.temperaturemap, pixel);
}
return values;
}
This maps image pixel colors back to continuous scalar values, allowing analytical operations like finding local minimum/maximum anomalies or performing secondary processing.