Hi Roger, Roger Breton via colorsync-users schrieb am 09.04.20 um 00:00:
I am given two sets of CIE Lab numbers, [ Reference: 50 40 40 ] and [ Sample: 50 34.25 45 ]. Between the two sets of numbers, I find 4.89 DE00 color difference.
My question is this, Is 4.89 the 'Total difference'? Yes.
As you may know, DE00 tolerances generally take the form of 'ellipses' (neutrals are more 'round', I'm told). Ellipsoid. We are talking about a 3D space. Picture a typical ellipse, it has a 'Major axis' (width) and a "Minor axis' (height). The Major axis is the longer dimension of the two.
Suppose the center of the ellipse is the Reference color above, is 4.89 to be considered the 'width' of the entire length of Major axis or is it twice the 'width', 4.89 on each 'side' of the center? Neither. Without knowing the two colours this cannot be answered. All colours on the surface of the ellipsoid have a colour difference of CIEDE2000 = 4.89 to the reference.
I'm pretty sure I know the answer but I'm running into what seems like a huge visual difference between the two sets of numbers and I want to be sure I'm not making a mistake in my interpretation of the DE00 difference.
Maybe your confusion comes from the fact that with dE*ab it is easy to imagine as it is the euclidian distance in 3D? There have been approaches to calculate a colour space from CIEDE2000. The result (if it perfectly worked) would be that the simple euclidian distance would give you the same results as CIEDE2000 in CIELAB. See e.g. https://www.semanticscholar.org/paper/Constructing-Euclidean-Color-Spaces-ba... Best regards Claas
/ Roger Breton www.graxx.ca
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