darktable ep 052 - The Color Lookup Table module

#darktable #tutorial #colorlookuptable
In this episode, we look at the Color Lookup Table (in dt 2.6.2).
As always, thanks to my tier 1 Patreon supporters:
Peter Barker
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Jon Hoskins
Namita Bhargava
Alun Spencer
Warren Smith
Stephen Diehl
Also, new Tier 3 supporter, Jan Boerenfluitjes.
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[@TheFearlessCooking]

very well explained. You are a good teacher :)

[@audio2u]

Thanks!

[@mfey53]

Great video, really helpful. As english is not my native language I appreciate the slow and clear pronounciation! 🤪😀😀 Martin

[@audio2u]

Glad to be of help!

[@maximmaximych]

Very good explanation, thanks!

[@audio2u]

You are welcome!

[@marcossaraiva4245]

Bruce you gave a big push for me in Darketable! ;-) Great work! Thanks

[@audio2u]

Glad to hear it, Marcos! That's why I am doing these videos. I just want to do my bit to spread the love for this awesome software. :)

[@uweinhamburg]

Hi Bruce, i have no usage for CLT *but* (again) your explanation went deeper than just for the single module. So i watched 22 minutes for something i will never use and i think that i have learned for darktable as a software in general. Waiting for you to start working with 3.0. I have downloaded it weeks ago - the first RC01 - and it is faster and stable. I love it. The 'outer' differences do not look that big but there has been a lot of tweaking inside in the machine. Thanks for sharing your knowledge 👍

[@audio2u]

Believe it or not, I never even got around to installing rc0! I went from 2.7 to 3.0 rc1. Spent a couple of hours playing with it yesterday. Lots of stuff to discover. Now u just have to find the time to document it all!

[@fotografie-joerglang]

Great video, great job, thanks a lot for this detailed explantation.

[@audio2u]

No worries!

[@dreydt9820]

I like these videos, very well explained though a little slow. But it goes in details into each module and really brings a lot. Well done !

[@audio2u]

Thanks Audrey. I figure a slightly slower delivery allows those who are struggling with a concept time to wrap their head around it. For everyone else, there's KZbin's playback speed control which allows you to pace it up a bit! 😃

[@dreydt9820]

@@audio2u Good advice actually ! I'll speed up a little bit the video pace then 😊

[@richardinmontreal396]

@@audio2u Don't change anything. Your technique is prefect! Mention to the viewers that they can use the speed control. Personally, I watch you at 1.25x. When I rewatched all the videos a 2nd time, I use 1.5x or 1.75x. If someone finds you speak to quickly, they can set the speed to 0.75x. Thanks for all your hard work, it is greatly appreciated!!

[@spark198rus]

13:30 daym

[@syteanric1868]

I managed to add more tiles a year ago by complete accident! I think it was control + slider on the squares but cant remember

[@pettere8429]

The absolute/relative is how the target color is shown. I.e. either in absolute Lab-color space values or relative to the source color.

[@tcoiler]

This is particularly useful when matching colors between images using the color picker. Pick a color from your source image and notice the LAB values returned. Select your destination image and the matching color patch. Set the "target color" dropdown to absolute and adjust the numeric values to match those in the color picker.

[@JillesvanGurp]

These look like they are complementary colors on the color wheel. en.wikipedia.org/wiki/Color_wheel Probably organized such that neighboring tiles are very different from each other. I'm guessing that the whole thing is done such that messing with one tile has minimal effect on the nearest tiles on the color wheel.

[@claudioabado3317]

@12:41 It's obvious this tool is severely missing a "Range" kind of control for the original swimsuit color was not entirely "replaced". There is some kind of "implicit" range into the underlying selection mechanism but it would fantastic if it would be under user control.

[@audio2u]

TBH, I have never used this module since doing the video. I'll need to do some research before tackling this again.

[@autoauto2000]

Olala... a Ford Focus RS and the shirt is to looong

[@audio2u]

Bwahaha!

[@claudioabado3317]

@10:19 The "Relative" vs "Absolute" color, though not documented (such a great piece of software but poorly documented IMO) refers to an ICC 'style' color rendering, one based on the White Point of the Destination. Since, the Source is not known here (could be sRGB, DisplayReferred), in principle, selecting Absolute should make colors "bluish" since sRGB has a "bluish" relative whiteness. Selecting Relative should keep colors devoid of all Desination White Point color and keeps colors "relative to the Destination (implicit = sRGB again) white point such that Lab = 100,0,0 is mapped out to RGB = 255, 255, 255. That's my "take". But this tool is pretty powerful. There is nothing like this in Photoshop? And if I understand correctly, it *is* a system of color-matching that could very well work off the base of an ICC profile. In fact, there could easily be a menu option to capture the Preset out to an ICC profile.

[@audio2u]

Ok, I'll take your word for it! 😃

[@claudioabado3317]

@@audio2u I was dead wrong: as I belabored my way with the control, I noticed I was getting all Zeroes on selected colors? And other times, I was getting the exact Lab values showing? In fact, if you reset the tool and select "Relative", all three sliders are shown as Zeroes, whatever patch selected, you see? Now if you select "Absolute", all three sliders show the Lab values of the selected patch. So that, patch #0 in Absolute "mode" is shown as L=37.99 a=13.26 b=14.06. This corresponds to the actual CIE 1931 D50 measurement of the actual "dark skin" patch using a spectrophotometer such as X-Rite i1Pro off the real ColorChecker chart.

[@audio2u]

Well, at least NOW I'll be able sleep at night! 😃

[@Chris-St-DE]

Simply select the first preset (Fuji Astia) and 49 patches are available (tested in V3.0RC1).

[@audio2u]

Thanks for that, Chris!

[@richardinmontreal396]

@@audio2u I tried this and it does work, BUT, it changed the color in the image. If I activate the module with the default 24 tiles, nothing changes until I move a slider. But, if I use the Fuji Astia preset, the colors change instantly.

[@leslieraven5696]

Hi Bruce, I am trying to replace a color to specific one (for example rgb(51, 107, 135). I am struggling to find out how to do this. Can you give me an advice, please. Many thanks

[@audio2u]

For this, I'd try the Colour Zones module. I covered this technique in one of my earlier videos. I think it was one of the Masks videos (ep 13-16, from memory).

[@leslieraven5696]

@@audio2u Thank you!

[@jnrickards]

This is good but choosing colours seems a bit haphazard. What if the bathing suit company had provided the colour codes for the different colours, how would one specify the colours in the LUT?

[@audio2u]

I thought about that after I had recorded. I don't have a good answer. There probably is a more accurate way. :(

[@jnrickards]

@@audio2u Maybe the documentation for dt3 will be more clear and more videos will be released on how to use it.

[@dasbobele6678]

Thanks for the great tutorial. By the way: isn't there any module that can change stuff to 'transparent'? :)

[@audio2u]

Not that I know of.

[@audio2u]

I must have been half asleep when I replied. I just "got it". #facepalm 😊

[@dasbobele6678]

@@audio2u as a German I just took it as a very cool reply ;)

[@JulesMoyaert_photo]

👍 Subscribed.

[@audio2u]

Cheers!

[@mickehog76]

Great video as always :). But it's difficult to concentrate on what you are saying 😜😂.

[@audio2u]

Yeah, sorry about that! Teigan is rather easy on the eye, isn't she? 😃

[@autoauto2000]

in German...Mittelwert oder gewichtetes Mittel

[@audio2u]

Aahhh... ok. No idea.

[@demarestk]

Hi Bruce, Rico has a video about downloaded LUTs: kzbin.info/www/bejne/rYexmGeXgK2iq9E But it's for the new 3D LUT system in darktable 3.0... Don't know if this would work in 2.6

[@audio2u]

I haven't had a chance to watch it yet. It's on my list...