Help to create a set of "PIXLS.US" color LUTs ?

#1

I’ve been thinking about that for quite a long time.
Knowing there are a lot of talented photographers here, I wonder if we could join our efforts to build a pack of free “PIXLS.US” color LUTs by people specifically from the PIXLS.US forum.

Color LUTs are extremely popular for simulating old film or color grading, e.g. to create a certain color mood for photographs (or videos). Lot of websites already propose Packs of Color LUTs (sometimes free, sometimes not), and I really think PIXLS.US could propose its own “open-source” pack, for everyone interested.

I’m not a photographer, so I won’t be able to help creating interesting color LUTs.
But I’m a developer with good experience of managing color LUTs, and what I propose here is a really simple way to build such a pack.

  • Basically, if you want to participate, the only thing I’m asking from you is to post a color image, and its modified version (modified, in the sense only colors are touched, so that there is still a perfect geometric match between the two images, no shift, no blur, etc.). The more different colors there is in the original image, the best.
    And also, give a consistent name to your color transformation.

For instance, something like:
(I took an example of an existing CLUT in G’MIC)

CLUT name: Summer

Original:

summer_000000
summer_000000.jpg1024×576 521 KB

Modified:

summer_000001
summer_000001.jpg1024×576 528 KB

  • From this pair of images, I’ll be able to create the corresponding color LUT, and make it available both as a .png HaldCLUT file, and as a compressed version to be integrated directly in a new section, in the filter Colors / Color presets in the G’MIC plug-in for GIMP and Krita.

It would be interesting to have various color transformations (e.g. including Black & White) to be included in the pack.

What do you think of the idea ? To me, it seems it’s an occasion to show your color retouching skills, and at the same time to contribute to the construction of a free Color LUTs pack for PIXLS.US.
Let me know if you find the idea interesting or not.

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#2

Hm, sounds like a new PlayLut challenge (like PlayRaw): Somebody provides a .tiff picture (neutral colours) and only newly created LUTs are allowed for processing, which will later be applied to 3 different pictures of the same genre and the best LUT wins … or so.

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#3

Here’s a first submission.

Original image:

ori1
ori1.jpg1280×1920 466 KB

The transformation implies several color (hue and saturation) and tone changes (mostly lifting the shadows). It kind of reminds me of the so-called “Instagram filter”, so I’d call it “Amstragram”:

amstragram1
amstragram1.jpg1280×1920 502 KB

And a variation with less lift in the shadows:
“Amstragram+”:

amstragram2
amstragram2.jpg1280×1920 524 KB

The names can be changed.

Edit: adding another one, I’d call “Autumn”, turning greens into and reds into gold/orange:

autumn
autumn.jpg1280×1920 466 KB

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#4

Very nice @sguyader, don’t you mind if I put these images in a repository on github ?
(I’m planning to create a code to automatically generates the CLUTs from the before-after examples, compress them and so on…) ?

PS : Otherwise, I’ll probably do it on one of our private repos here at the lab.

#5

I have here a shot from an old camera.

Original colors:

DSCF5273_01
DSCF5273_01.png3264×2448 10.4 MB

“Metropolis”

DSCF5273
DSCF5273.png3264×2448 12 MB

Do whatever you wish with them :slight_smile: .

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#6

Might be worth asking @stefan.chirila about including his (wonderful!) series of color work (customCHROME). He’s got like half a dozen pretty LUTs that would be awesome to include!

http://www.stefanchirila.com/customchrome/

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#7

So, I’ve made some progress on this, from a ‘technical’ point of view.
I wrote a first script to convert the examples as CLUTs, and compress them for a future inclusion in G’MIC (not done yet).
I’ve also updated the web ‘Color Presets’ web page on the G’MIC site, with a new category ‘PIXLS.US’ :

https://gmic.eu/color_presets/pixlsus_sample_7.shtml#browse

So far, we have 4 CLUTs :slight_smile:

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#8

Here’s my humble contribution. I already have a HaldCLUT for this:

Alberto%20Street
Alberto Street.png1728×1728 2 MB

Example:

#9

What a lovely Idea!

Is there a best practices for creating those LUTs? I imagine when creating a LUT with just one picture which contains only a limited amount of colors, this LUT will be useful for similar pics, but not all.
I.e.: colors I didn’t touch will stay untouched whereas others might be heavily wrangled.

Referring to your example, it almost has no reds just green and blues. But your LUT goes in a very specific style direction. Would you recommend pics with a broader spectrum of colors to generate the CLUTs from?

Is there going to be a curation as to what these LUTs will do, or is basically everyone invited to contribute whatever and the final user has to make the final decision?

This post sounds like criticism, it’s not! :slight_smile: I love this!

EDIT: I have to learn to read! Sorry, ‘the more colors the better’ you state acutally…I was blind because I am so excited!!! :smiley:

#10

@David_Tschumperle sure, you can put my images on your github repo.

#11

Yes, definitely, having an image with a lot of colors helps having a more precise CLUT estimation !
In the example of @Thomas_Do (Metropolis), there are mainly blue tones in the original photograph, and very few reds. But the red pixels are transformed to very saturated colors, and this has a huge impact on how the estimated CLUT behaves for the redish tones (see the CLUT applied on @patdavid’s face here for instance : https://gmic.eu/color_presets/pixlsus_sample_8.shtml#browse ).

The more colors you have in your original image, the more finely you can tune the color transformation.

It would be even a good idea to define a kind of “reference” image to work with, just as you do in PlayRaw.

That would be interesting to have some validation by experts, but how this can be done and by whom, is probably not so easy to set up. So, unless we get hundreds of contributions, I don’t think this is useful to have a selection committee :slight_smile:
I am quite confident that here, people will propose color transformations of which they are proud and that they think interesting.

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#12

Perhaps set some minimal requirements on what constitutes a good reference image, and a simple test to determine whether an image is okay.

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#13

@agriggio, what is the name you propose for your CLUT ?

#15

I’ll see how that goes. At the moment it’s hard to craft a grungy look by staring at a beautiful bouquet of colorful flowers. Does not compute :smile:

That would be appreciated. For now, looking at @patdavid’s face, beautiful as it is, might not suffice to finetune that look. :blush:

#16

Also, I keep track of each contributor for each CLUT, so if you want full credits, do not forget to tell your full name (otherwise, I can use only a pseudo).

#17

I wonder if it is worth to include colour patches and gradients into the reference images, as they appear in typical test images. That would prevent having some sparse areas in the CLUTs. I mean something like this: https://i0.wp.com/mirrorless-landscapes.de/wp-content/uploads/2016/10/Testbild.jpg.

Hm, that makes me think … we need a freely licensed pixls.us test image, similar to the one above, but including more scenes (e.g. more different skin colours, landscape in sunrise/ sunset, night landscape with milky way, some food, …).

#18

gosh yes! I feel honoured you guys even care about my presets. I am so behind on that project; I have a lot in the works that I need to make packs for. Any of them of particular interest?

#19

So, here are my contributions:

The Original:

PPG_Original
PPG_Original.jpg1920×1280 1.26 MB

Delicatessen:

PPG_Delicatessen
PPG_Delicatessen.jpg1920×1280 1.27 MB

Progressen:

PPG_Progressen
PPG_Progressen.jpg1920×1280 1.28 MB

Hypressen:

PPG_Hypressen
PPG_Hypressen.jpg1920×1280 1.53 MB

Pseudonym is fine with me PPG or PhotoPhysicsGuy.

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#20

no idea…

#21

Here’s a HALDclut for pseudogrey:

pseudogrey_hc.png1728×1728 342 KB

I made the HALDclut with the ImageMagick command:

convert hald:12 -colorspace Gray pg_clut.png -clut -depth 8 pseudogrey_hc.png

See the thread Digital B&W Conversion (GIMP)

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