Because an object’s color is dependent on how our brains process the data provided by the rods and cones in our eyes, there can be two colors that are technically different, but the human eye can not perceive that difference. There is a threshold of noticeability at which two colors can be perceived as different, and that threshold is referred to as Delta E.

Delta E is measured on a scale of 1-100. When a Delta E is listed, these are the ranges in which it is defined.

- Less than 1: Not perceptible
- 1-2: Only perceptible under close scrutiny
- 2-10: Slightly perceptible
- 11-49: Perceptibly different, but still appear similar
- 100: Opposite/complementary colors on the color wheel

This guide covers the general concept of Delta E, but there are also highly intricate formulas that we use to determine these results. In 1976, the original formula was determined, which was identical to the Euclidean distance formula. This is due to its suitability to the CIE L.A.B. Color Space’s three-dimensional model that is used to measure all the possible hues. Unfortunately, this model fell short in measuring the lightness of a color, so therefore it could not differentiate between two different hues when fully saturated.

In 1994, CIE determined a methodology that takes into account lightness, chroma and hue value. This introduced a far more complicated formula than necessary to calculate Delta E, but it also created a far more useful, accurate and actionable results. While this did not factor in lightness to the fullest extent possible, it is still considered suitable for textile and printing applications.

In 2000, CIE introduced what is known as dE00. It consists of highly-sophisticated and very complex formulae, taking lightness into account much more than previous calculations. Although this opens up new possibilities, there is still one measure that can supersede any formula, and that is the perception of the end user. However, by utilizing these advanced calculations, we can more easily and efficiently reach our desired color outcome.