This interactive color picker demonstrates the HCL (Hue-Chroma-Luminance) color space for perceptually uniform color selection. Three sliders adjust hue, chroma, and luminance, while gradient canvas backgrounds show how each parameter affects the final color. The interface converts between HCL and hex values bidirectionally, with a preview box and text input for direct hex entry. The visualization uses D3.js v5 for color space conversions and Topologica for reactive data flow, while rendering gradient backgrounds to canvas and checking color gamut validity with D3's displayable method.