- What is CIE LAB and why does it matter for color work?
- CIE L*a*b* (CIELAB) is a color space defined by the International Commission on Illumination (CIE) that models human color perception. The three axes are L* (lightness, 0 = black to 100 = white), a* (green–red), and b* (blue–yellow). Because equal numerical steps in LAB correspond to roughly equal perceptual differences — unlike RGB or CMYK — it is the preferred space for color comparison, color correction, and finding the nearest Pantone match. Print and textile industries specify colors in LAB because it is device-independent and illuminant-aware.
- What is Delta-E 2000 and how do I read the match scores?
- Delta-E 2000 (CIEDE2000) is the most accurate perceptual color difference formula as of the 2000 CIE standard. It improves on earlier formulas (dE76, dE94) by weighting differences in lightness, chroma, and hue separately and applying corrections for the blue region where human vision is less sensitive. Interpreting the scores: 0–1 = imperceptible difference (virtually identical to the eye); 1–2 = just noticeable; 2–5 = visible but close match; 5–10 = obvious difference; above 10 = completely different colors. For Pantone specification you typically want a match with dE < 3.
- How accurate is the Pantone finder — and why might it differ from physical Pantone swatches?
- The Pantone matches in this tool are computed against sRGB approximations of Pantone colors (the standard open dataset). Physical Pantone inks are measured in a controlled D50 illuminant environment and include substrate and surface finish effects that cannot be reproduced on screen. Screen gamuts also cannot display some highly saturated Pantone inks at all. Use this tool to get the nearest candidate names for reference — always verify against a physical Pantone fan deck before specifying for print. The Pantone dataset includes 2,310 Pantone Fashion, Home + Interiors (FHI) and related color names.
- Can I convert a CMYK value from InDesign or Illustrator directly?
- Yes — type the C, M, Y, K percentages from your design software directly into the CMYK fields (0–100 scale). Note that this tool applies device-independent CMYK math (no ICC profile), which matches what you see on screen. For a press-accurate conversion you would need to apply a CMYK output profile (e.g. FOGRA39 or US Web Coated SWOP v2) — something only full color management software like Adobe Photoshop can do precisely. For most design reference work, the device CMYK conversion here is accurate enough.
- What is the D50 illuminant and why does this converter use it for LAB?
- D50 is a standard illuminant that simulates a 5000 K daylight source — the viewing condition used in the printing and graphic arts industries and adopted by the ICC (International Color Consortium) as the reference white for profile connection spaces. When LAB values are specified in a D50 context (as in ICC profiles and Pantone books), a D65 illuminant (6500 K, used as sRGB white) must be adapted to D50 via the Bradford chromatic adaptation transform before computing LAB. This converter does that adaptation automatically using culori.js, which follows the ICC standard exactly.