CIE 1931 xy color space diagram. Drawn (or rather programmatically generated) from scratch, but the visual design is based on <a href="//commons.wikimedia.org/wiki/File:CIExy1931.png" title="File:CIExy1931.png">CIExy1931.png</a> by <a href="https://en.wikipedia.org/wiki/User:PAR" class="extiw" title="w:User:PAR">PAR</a>. Major differences:
<ul><li>Colors outside the sRGB triangle are clipped toward the sRGB white point, so they have more accurate hues. The original image (and most other images of this type) clips each sRGB channel independently to zero, which among other things leads to the whole top of the diagram being colored <style data-mw-deduplicate="TemplateStyles:r360851041">.mw-parser-output .monospaced{font-family:monospace,monospace}</style><span class="monospaced">#00FF00</span> (sRGB primary green) when it should be more of a cyan.</li>
<li>Luminance inside the triangle was reduced somewhat. Maximum luminance (the <a href="https://en.wikipedia.org/wiki/uniform_norm" class="extiw" title="w:uniform norm">infinity norm</a>) creates a three-pointed star artifact (the lines are <link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r360851041"><span class="monospaced">#FFFF00</span>, <link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r360851041"><span class="monospaced">#FF00FF</span> and <link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r360851041"><span class="monospaced">#00FFFF</span>). Constant luminance (1-norm) looks rather dull. An intermediate <i>p</i>-norm makes nice-looking results without the star. This background image uses <i>p</i>=5. Gone with the star is the clearly defined white of the D65 white point, which is also an sRGB artifact.</li>
<li>Blurring of the sRGB triangle edges to hide artifacts there. This means the colors near the boundary are slightly less accurate (not maximally saturated). I prefer this to the line artifacts, but it's an issue that could be debated.</li>
<li>Labels at uniform 20nm intervals; left out 380nm and 700nm because the locus doesn't really stop there or anywhere, it just fades into nothingness; no grid on the <span class="mwe-math-element"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle x+y&gt;1}"><semantics><mrow class="MJX-TeXAtom-ORD"><mstyle displaystyle="true" scriptlevel="0"><mi>x</mi><mo>+</mo><mi>y</mi><mo>&gt;</mo><mn>1</mn></mstyle></mrow><annotation encoding="application/x-tex">{\displaystyle x+y&gt;1}</annotation></semantics></math></span><img src="https://wikimedia.org/api/rest_v1/media/math/render/svg/cc1af357fbb48d9756c92f3f3023997cf307c865" class="mwe-math-fallback-image-inline" aria-hidden="true" style="vertical-align: -0.671ex; width:9.586ex; height:2.509ex;" alt="{\displaystyle x+y&gt;1}"></span> region; random tweaks, etc.</li></ul>
<a href="//commons.wikimedia.org/wiki/User:BenRG" title="User:BenRG">BenRG</a>
Own work based on: <a href="//commons.wikimedia.org/wiki/File:CIExy1931.svg" title="File:CIExy1931.svg">CIExy1931.svg</a>