Colour Management Tools

Delta E calculator (ΔE76 and ΔE2000)

Compare two Lab measurements and see the colour difference by both the CIE76 and CIEDE2000 methods, side by side.

Delta E puts a number on the difference between two colours. It is the language colour agreements are written in, and the reason a press operator and a customer can stop arguing about whether a job matches.

Two methods are in common use and they do not give the same answer. CIE76 is plain geometric distance in Lab space. CIEDE2000 corrects for the fact that human vision is not equally sensitive across that space, and it is what most modern print specifications call for.

Calculator

How to use it

Enter Reference L*
Enter Reference a*
Enter Reference b*
Enter Sample L*
Enter Sample a*
Enter Sample b*

Formula

ΔE76 = √( ΔL*² + Δa*² + Δb*² ) ΔE2000 weights lightness, chroma and hue separately, adds a rotation term for the blue region, and is defined as: ΔE00 = √[ (ΔL'/kL·SL)² + (ΔC'/kC·SC)² + (ΔH'/kH·SH)² + RT·(ΔC'/kC·SC)(ΔH'/kH·SH) ] This calculator uses kL = kC = kH = 1.

Worked example

Reference L* 50.00, a* 2.60, b* -1.00 against a sample at L* 50.00, a* 0.00, b* 0.00 gives CIE76 2.79 and CIEDE2000 3.69. The two methods disagree because the difference here is almost entirely a chroma shift at low chroma, which CIEDE2000 weights more heavily than plain geometric distance does. Always state which method a tolerance refers to.

Assumptions

Both colours are entered as CIELAB values measured under the same conditions: same illuminant, same observer, same measurement geometry and the same backing.
The parametric factors kL, kC and kH are all set to 1, which is the normal graphic arts case.

Limitations

Every calculator on this site gives a planning figure, not a production guarantee. Check the result against your own records before committing material or money to it.

Delta E describes a difference, not whether a job is acceptable. The tolerance belongs in your specification.
Comparing measurements taken under different conditions produces a meaningless number. M0, M1 and M2 measurement modes in particular are not interchangeable, especially on substrates containing optical brighteners.
A single patch tells you about one patch. Press conformance needs a set of readings across the sheet or web.

Common mistakes

Quoting a Delta E without saying which method was used. ΔE76 and ΔE2000 values are not comparable.
Mixing measurement modes between reference and sample, then treating the difference as a print problem.
Carrying one customer tolerance across to another process or substrate that cannot physically hold it.

Frequently asked questions

What is Delta E?

Delta E is a single number describing the difference between two colours. Zero means the two measurements are identical. Larger numbers mean a bigger difference, and beyond a certain point the difference becomes visible to a normal observer.

What is the difference between ΔE76 and ΔE2000?

ΔE76 is the straight line distance between two points in Lab space. ΔE2000 adjusts that distance to match human perception more closely, weighting lightness, chroma and hue differently and correcting for the blue region. For the same pair of colours the two methods usually give different numbers.

Which Delta E method should I use?

Use whichever your specification names, and state it whenever you quote a value. Most current print standards and customer specifications are written around ΔE2000.

What Delta E is acceptable?

That depends on the agreement. Brand colours are normally held tighter than image areas, and the tolerance has to be achievable on the substrate and process in question. Agree it in writing before production rather than arguing after it.