31:T740,// takes wavelength in nm and returns an rgba value function wavelengthToColor(wavelength) { let R, G, B, alpha, colorSpace, wl = wavelength, gamma = 1; if (wl >= 380 && wl < 440) { R = -1 * (wl - 440) / (440 - 380); G = 0; B = 1; } else if (wl >= 440 && wl < 490) { R = 0; G = (wl - 440) / (490 - 440); B = 1; } else if (wl >= 490 && wl < 510) { R = 0; G = 1; B = -1 * (wl - 510) / (510 - 490); } else if (wl >= 510 && wl < 580) { R = (wl - 510) / (580 - 510); G = 1; B = 0; } else if (wl >= 580 && wl < 645) { R = 1; G = -1 * (wl - 645) / (645 - 580); B = 0.0; } else if (wl >= 645 && wl <= 780) { R = 1; G = 0; B = 0; } else { R = 0; G = 0; B = 0; } // intensty is lower at the edges of the visible spectrum. if (wl > 780 || wl < 380) { alpha = 0; } else if (wl > 700) { alpha = (780 - wl) / (780 - 700); } else if (wl < 420) { alpha = (wl - 380) / (420 - 380); } else { alpha = 1; } colorSpace = ["rgba(" + (R * 100) + "%," + (G * 100) + "%," + (B * 100) + "%, " + alpha + ")", R, G, B, alpha] // colorSpace is an array with 5 elements. // The first element is the complete code as a string. // Use colorSpace[0] as is to display the desired color. // use the last four elements alone or together to access each of the individual r, g, b and a channels. return colorSpace; }32:[] 2f:{"title":"Wavelengths and Spectral Colours","cells":[{"id":0,"value":"md`# Wavelengths and Spectral Colours`","pinned":false,"hidden":false,"mode":"ojs"},{"id":112,"value":"md `Wavelength (nm) range of visible spectrum, with a floating point RGB converted value.`","pinned":false,"hidden":false,"mode":"ojs"},{"id":40,"value":"viewof x = {\n const div = html`\n \n nanometres (nm)\n`;\n const range = div.querySelector(\"[type=range]\");\n const number = div.querySelector(\"[type=number]\");\n div.value = range.value = number.value = 400;\n range.oninput = () => number.value = div.value = range.valueAsNumber;\n number.oninput = () => range.value = div.value = number.valueAsNumber;\n return div;\n}","pinned":false,"hidden":false,"mode":"ojs"},{"id":86,"value":"html`

\n\n

`","pinned":false,"hidden":false,"mode":"ojs"},{"id":100,"value":"md `__Wavelength__: ${x.toFixed(1)} nm| __${tex`\\lambda`}__: ${x.toFixed(0) / 1000} ${tex`\\mu`} (microns) | __RGB__: (${wavelengthToColor(x)[1].toFixed(2)}, ${wavelengthToColor(x)[2].toFixed(2)}, ${wavelengthToColor(x)[3].toFixed(2)})`","pinned":false,"hidden":false,"mode":"ojs"},{"id":106,"value":"html `

`","pinned":false,"hidden":false,"mode":"ojs"},{"id":210,"value":"viewof t = table(wavedata)","pinned":false,"hidden":false,"mode":"ojs"},{"id":304,"value":"html`

`","pinned":false,"hidden":false,"mode":"ojs"},{"id":302,"value":"md`## Visible Spectrum`","pinned":false,"hidden":false,"mode":"ojs"},{"id":293,"value":"ramp(t => {\n const i = Math.round(t * (830 - 390) + 390) - 390;\n const xyz = cmf.slice(i * 3, i * 3 + 3);\n const rgb = xyz_rgb(xyz);\n return `rgb(${rgb.map(c => Math.round(c * 255))})`;\n})","pinned":false,"hidden":false,"mode":"ojs"},{"id":322,"value":"function xyz_rgb(xyz) {\n return lrgb_rgb(matrix_multiply_vector(matrix_xyzd50_lrgb, xyz));\n}","pinned":false,"hidden":false,"mode":"ojs"},{"id":155,"value":"html `

`","pinned":false,"hidden":false,"mode":"ojs"},{"id":104,"value":"md `## References`","pinned":false,"hidden":false,"mode":"ojs"},{"id":147,"value":"md`Color - The Physics Hypertextbook [[site]](https://physics.info/color/)`","pinned":false,"hidden":false,"mode":"ojs"},{"id":121,"value":"html`

`","pinned":false,"hidden":false,"mode":"ojs"},{"id":6,"value":"$31","pinned":false,"hidden":false,"mode":"ojs"},{"id":199,"value":"wavedata = [\n {\n \"colour\": \"red\",\n \"primary (nm)\": 700,\n \"range (start)\": 620,\n \"range (end)\": 800\n },\n {\n \"colour\": \"orange\",\n \"primary (nm)\": 0,\n \"range (start)\": 590,\n \"range (end)\": 620\n },\n {\n \"colour\": \"yellow\",\n \"primary (nm)\": 0,\n \"range (start)\": 560,\n \"range (end)\": 590\n },\n {\n \"colour\": \"green\",\n \"primary (nm)\": 546.1,\n \"range (start)\": 480,\n \"range (end)\": 560\n },\n {\n \"colour\": \"blue\",\n \"primary (nm)\": 435.8,\n \"range (start)\": 450,\n \"range (end)\": 480\n },\n {\n \"colour\": \"violet\",\n \"primary (nm)\": 0,\n \"range (start)\": 400,\n \"range (end)\": 450\n }\n]","pinned":false,"hidden":false,"mode":"ojs"},{"id":170,"value":"d3 = require(\"d3-scale-chromatic@1\", \"d3-interpolate@1\", \"d3@5\")","pinned":false,"hidden":false,"mode":"ojs"},{"id":31,"value":"wavelengthToColor(x)","pinned":false,"hidden":false,"mode":"ojs"},{"id":90,"value":"color = wavelengthToColor(x)[0]","pinned":false,"hidden":false,"mode":"ojs"},{"id":193,"value":"import {table} from \"@tmcw/tables@444\"","pinned":false,"hidden":false,"mode":"ojs"},{"id":321,"value":"import {cmf, ramp} from \"@mbostock/visible-spectrum\"","pinned":false,"hidden":false,"mode":"ojs"},{"id":336,"value":"import {\n lrgb_rgb,\n matrix_xyzd65_lrgb,\n matrix_xyzd50_lrgb,\n matrix_multiply_vector\n} from \"@mbostock/lab-and-rgb\"","pinned":false,"hidden":false,"mode":"ojs"}],"files":"$W32","stdlib":"1","titling":"auto"}