GCM 360 Lecture Notes - Lecture 5: Horse Length, Prepress
21 Dec 2020
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Gcm 360 | week 5 - l*a* b* and delta e. Delta e is calculated from l* a* b* If we can describe a colour by a number, then we can also describe a colour difference by a number too. Having a single number for colour difference is very useful. Basing delta e on l* a* b* gives us a perceptually-relevant metric. 1 delta e is a jnd - just noticeable difference. Delta e of 2 is a very close match. Delta e of 2-6 is generally acceptable in the graphic arts industry. A delta e of 6-9 is likely to noticeable and probably unacceptable. Delta e tolerance will vary between different industries - and how much you are prepared to pay! It doesn"t matter which you call reference or target. Negative numbers are removed by square (l1 - l2)^2. (5-10)^2 = (-5)^2 = (-5 x -5) = 25.
