The CIELAB lecture

CIELAB color space is the most common way to measure, specify, and provide tolerances for color. John the Math Guy describes the CIELAB color space, along with his rants about how it doesn't quite work the way we want it to.

[swedella]

Thank you SO much, from a math illiterate with a deep interest in color. I 've noticed with my own eyes that available color spaces and tools have some fundamental and VERY annoying flaws, but I could not understand what or who had caused them. Now you've explained both color history and math in a way that my usually math-resistant brain can actually grasp. And I loved your tirades! My husband just came in to see what was so funny and was surprised to find me looking at a video full of ("very ugly") equations.

[PragMero]

as an unemployed latin american, this video was extremely entertaining

[MauroLussignoli]

Thanks a lot for your "tirades" Dr. Seymour. 👍

[andresopera]

Hi John, excellent video! I also like the sense of humor, very important when talking about CIELAB :)) On the other hand, could you, perhaps, review, give us a lecture on OKLAB, this other color space? I would appreciate it, thanksss

[cmyk]

I’d love to have a colored-in and stacked 3D model of the diagram at 16:30 for decoration.

[dannown]

you could simplify the function at 14:07 with =mod(degrees(atan2(i9, j9)), 360).

[stevepivi]

Great lecture -- it helped me a lot with my Bachelor Thesis. Thank you a lot, professor.

[claudiowilmanns]

Great stuff and fun to watch! Thanks :-)

[willboler]

Thank you, I had some education on different color spaces and am working on a PhD project for anomaly detection in CV, but am using RGB Manhattan distance for estimating the error. I was advised several years ago to just stick with RGB, but I had recently been wondering if putting it in LAB would make any difference. Idk if we ever went over delta-E, but it makes sense that might be what I want to use. For example, my issue is white cars against a grassy background appear more anomalous against a black background, and other colors have varying behavior under different conditions. I think I have reasoning finally to dig into the literature.

[andrewrossetti]

You went into great detail about DE:76 and DE:CMC; but didn't explain how
DE00 was created or what it is intended to improve over prior tolerance standards.  The way it is
explained in the industry sounds very similar to CMC, but besides a more
complicated formula I'm assuming there are other benefits.  Can you do a
lecture for youtube on it at some point?  Based on what you showed CMC is using the
a linear hue angle like CIELAB in the formula, does DE:OO use a hue angle more aligned
to a human observer?

[caoimghgin]

The L* value of swatch #3 in the Kodak Gray Scale chart is L*50? I'd suspect swatch M matches the 'human visual perception' of a true mid-tone, or L*50.

[dottormaelstrom]

For the mathematically educated I suggest you check out the work of Edoardo Provenzi on color perception

[sigismundfreude]

Video and photographers are allowed to deal with Lab intensively. A good example is the software product 3D LUT Creator. In the training video on YT titled "HSP and LAB color models in 3D LUT Creator. Part 1", about 3 minutes in, it is shown that the primary colors (RGB, CMY) in Photoshop make "loops" in the Lab space when you change their brightness, which would correspond to opening or closing an aperture. What you would want are straight lines parallel to L-axis and not loops. That's why the authors of 3D LUT Creator introduced the HSP color space to compensate for this weakness. John, what do you think about this? Wasn't that also one of your tirades?

[ofstudiophotography]

This is very entertaining...do I have a problem?
so...a 1 unit of Delta E 2000 is still the slightest amount that human eyes could decipher. Is that correct? A delta E 2000 at 2.0 among 90% of my color patches is...good? sorry psudo color enthusiast here

[SHDEdits]

Delta E gotta be the largest polishing of a turd in history.

[triskadka]

Sir, can i have the soreadsheet? Thank you!

[marceloferraris]

Hi John, hope you are doing well.. great video!
John, I have one question regarding colour differences in offset printing though. Is it valid to say that Delta E 1 tolerance is indeed capable of delivering a Delta E 2 between repeated jobs? If I print one day a colour which is Delta E 1 from my target and the next day I print this job again and I have again a Delta E 1 deviation but in this case my print reading is pointing at the bottom end of the ellipse and the first run was pointing to the top of the ellipse.. so I am Delta E 2 from these two press runs, which yes they are a PASS for the machine BUT between run, they look unacceptable.
Is there a way to avoid this? how one can communicate this in a press room? Can I match the top/bottom half of the circle only in the spectrophotometer? If that's the case, it might need to vary according to the colour I am printing which can be an absolute hassle for printers and everyone involved.. What's your take on this problem? Thanks in advance!

[davewyble]

Instead of saying "Pythagorean theorem" you could be more pretentious and slightly more accurate by saying "Mahalanobis distance"

[lifeunderthemic]

Goethe's color theory still standing on the rotting corpse of Newton's of corporate interest.