Colour Mixing

Colour difference calculator

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Perceptual difference ΔE 4.7 — noticeable side by side

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Local · CIE76 in Lab, not RGB distance

Measures the perceptual distance between two colours as ΔE in CIE Lab — the space designed so that equal numeric distances look like equal differences.

How to use the colour difference calculator

1 Set your colour, by picker or by typing a hex value.

2 Switch the format if you need RGB, HSL or OKLCH rather than hex.

3 Tap any swatch to copy it, or copy the whole set at once.

RGB distance is the obvious approach and it is wrong: it treats a change in blue as being as visible as the same change in green, and human vision is far more sensitive to green. Lab was built to fix exactly that. The thresholds worth remembering are that ΔE under 1 is not perceptible to the human eye, 1 to 2 is perceptible only on close inspection, 2 to 10 is perceptible at a glance, and above 50 the colours are more different than they are alike. This uses the 1976 formula, which is simple and sufficient for the verdict; CIEDE2000 is more accurate for saturated blues if the number itself matters.

Questions

What is a ΔE of 1? −

The threshold of perceptibility — under 1 the human eye cannot tell the two apart.

Why not just compare RGB values? +

Which formula is this? +

What ΔE do print buyers accept? +

Which colour format should I use? +

Sources

CIE — colour difference and the Lab space

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