ΔE — "delta E" — is a single number that describes how different two colors look to the human eye. It was developed by the CIE (Commission internationale de l'éclairage) to put perceived color difference on an objective scale. Smaller numbers mean the colors are closer; zero means identical.

When you click a pixel on your photograph, Palette reads that pixel's red/green/blue value and converts it to CIE Lab — a color space designed so that equal distances correspond roughly to equal perceived differences. It then measures the distance from your pick to every glass and every Pantone color in its catalog, and ranks the nearest five in each section.

The hex color used for each glass SKU is extracted automatically from the manufacturer's product photograph — center-cropped, background-masked, and averaged. Pantone entries use their published sRGB values. This means glass matches are a ranking by photo color, not by fired color. A fired piece will always reveal something you can't read from a thumbnail; treat the ranking as a starting point.

Palette uses CIEDE2000 (CIE standard, 2001) — the current best-practice color-difference formula. Unlike the older ΔE76 (Euclidean distance in Lab), CIEDE2000 applies lightness, chroma, and hue weighting functions, plus a chroma-rotation term that corrects for the fact that human perception of color difference is not uniform across the spectrum. The blue-green region in particular appears less different than ΔE76 would predict; CIEDE2000 accounts for that. Result: rankings are closer to how a trained colorist would order matches side by side.

Unlike paint or print, glass is a translucent material that behaves differently under back-light, reflected light, stacked layers, and in the kiln. ΔE measures one dimension of color — how your source color compares to a sample photograph of each product. Compatibility, opacity, strikers, and reactive metals (copper, sulfur) all show up in the match card's reaction dots and firing notes, but they aren't part of the ΔE score itself.

Dichroic glass is excluded from rankings. A dichroic sheet is a clear or black base with a thin metallic-oxide coating — the photograph captures the coating's sheen, not the glass underneath, so the extracted hex isn't a fair match target. Dichroic is still fully browsable under the Bullseye catalog (Form filter → Dichroic) for when you specifically want an accent piece.