Color.io is Awesome for Color Correction / Grading and LUT Generation

[PhLo]

Color.io - Analog Photo Editor & Look Designer

Over the last few weeks I have struggled to make decent LUTs to transform Log footage from my 360 camera. I finally came up with a LUT that works well with any footage I record. I used DaVinci Resolve, Affinity Photo, Capture One and LUTCreator.js to come up with a color grading LUT. It took many iterations before I was satisfied.

I did a web search today for AI LUT Generator because I thought maybe there was a more automatic way to do color grading. There are such things in existence now, but I clicked on Color.io in the search results. It is an amazing online color grading tool. In a few clicks on their intuitive color tools, I was able to make an amazing color grade that rivals or surpasses all my experiments with DaVinci Resolve and other software. In short, I’d say it is better and easier to create pleasing LUTs with Color.io than any other tool I’ve tried so far.

The only “unfortunate” thing is that it is not a free service. I might end up paying for a month just so I can export a few LUTs because they were so easy to make and look really good. Considering how much time I fiddled with other software, and I was able to get the same or better results in 5 minutes on color.io… it feels like it might be worth it.

[MusicalBox]

Thanks for the info @PhLo.
I’ve used Photoshop a few times to create my own LUTs
But…

@PhLo

The only “unfortunate” thing is that it (Color.io) is not a free service.

Obviously, Photoshop isn’t free either. But there is an online service called Photopea that is almost identical to Photoshop, but completely free (with non-so-intrusive ads).

Add any Adjustment Layers and/or Image Adjustments in your Photopea project and when you’re satisfied, go to File > Export Color Lookup… to export your LUT.

You can then use this LUT in your Shotcut project.

[PhLo]

Cool, I’ll check it out sometime. I don’t lack ways to make LUTs. I have many. But some tools just work better than others. I used to think DaVinci Resolve was the best way to make LUTs. It has great color correction tools, but color.io worked far faster, and with almost no effort to get the grade I wanted.

I am familiar with standard color correction tools such as curves, levels, color balance, white balance, and so on… but sometimes there are quirky things going on in a grade that are hard to define, and these traditional tools take hairpin precision adjustments to get a good result. They would be more effective if they were HUGE, full-screen, so small movements were more subtle in how the changes effect the image. As in, the interface of the color wheel or curves is too small because a single pixel of movement in any direction blows it out of anything looking nice. DaVinci Resolve and Capture One intentionally make it so bigger movements with the mouse create smaller effects, so it’s way easier to finetune color adjustments. I’m guessing that, under the hood, the adjustments have floating point numeric values instead of integers so that they can be very subtle. Shotcut could benefit from this idea as well - some kind of logarithmic movement algorithm where the mouse dragging inside color wheels has a very small effect unless dragged very fast. It’s a rare, distinctive feature that only a few apps support. Probably someone with industry colorist training can use any kind of tool to get a good result, but I prefer the easiest path to get from A to B so as not to waste time.

Affinity Photo has most of the standard image editing tools found in Photoshop (minus some of the latest additions like AI generative content), including LUT export. I use Affinity most of the time. For RAW photo development I use Capture One, as I find it is better than Lightroom. I have never been satisfied with any of the freeware RAW developing software. I actually hate shooting in RAW because it means I’ll never actually go back and develop those photos - takes too long. But the results are crazy good if I take the time.

[PhLo]

I gave Photopea a quick look. After seeing it again, I realized I played with it quite some time ago. It’s pretty awesome that it can do much of what Photoshop once did (it looks like an older version of Photoshop), but in a browser. For color correction I don’t think it would help me in particular, as I need very specific, above-the-norm set of color grading tools to get quick, perfectionist results. For example, it can be quite finnicky to get a good color grade on Log footage using standard color tools like curves, contrast, saturation, white balance, etc. But for normal Photoshop uses, Photopea seems like it would be great. Since I have Affinity Photo, GIMP, Krita, and others, I probably won’t have a particular need only it can fill.

[PhLo]

After encountering truly nitty gritty color grading challenges that no simple tool can solve, I had to go back to DaVinci Resolve in the end. To be clear, for color grading, not for everything. I create a LUT in Resolve, then use it to grade all my footage in Shotcut. For 2 to 5 click quick color grades, Color.io has a lot of potential, but for the crap I have to deal with, I need full control. For example, in my footage there are weird green shadow color artifacts right next to red artifacts. None of these colors exist in nature, but the camera sensor isn’t great in low light and adds such junk. So it’s my challenge to get rid of them. Only with magic-wand style selection tools can I target these color artifacts to reduce them - referred to as “Qualifiers” in DaVinci Resolve. Otherwise, with curves, levels, color balance and other traditional tools, the entire image will be affected.

To give a small idea, here’s what I have to deal with. Granted, this is a consumer level 360 camera, and not a pro camera with a huge sensor, so this junk is expected in low light. But I find it so ugly as to be unacceptable and worth attempting to fix.

original flat log footage, before any correction:

after doing general correction that looks good for the well-lit areas of the footage:

You might think, “Oh, there’s tons of moss on those rocks, and that’s why they are green.” Nope, not in this case. It’s simply how the sensor badly captures color data in low light. It’s highly compressed and generally lossy. The only way to get rid of those unsightly color casts without affecting other unintended areas (like red things and green trees/plants) is to use very fine-tuned masking techniques. Again, this is done through the Qualifier tool in DaVinci Resolve - and MANY nodes in the filter tree.

Here’s my final graded result:

To the untrained eye, this final result might look very similar to the original flat log footage. But these shadows aren’t intended to be a rainbow. They are dark in reality. Normal color grading tools create the nasty red and green rainbow in the shadows, and only advanced tools can tame them back to normal hues without distorting color elsewhere in the image.

It takes hours of painstaking trial and error to come up with these LUTs in DaVinci Resolve, but only DaVinci Resolve can do it. There are no other tools that I’m aware of that can perform this kind of color grading surgery. Unless you break your entire movie into thousands of individual photos and edit them individually in Photoshop, GIMP, or the like! Ha, that would be ridiculous!

I realize this is not Shotcut related, but I think it’s important to discuss. Perhaps in the future, as Shotcut continues to advance, such things will be possible. Most of us freeware and open source enthusiasts know when to combine different tools to achieve particular results in the most efficient and least stressful manner. As things are right now, I have to use Shotcut for my overall editor, so this isn’t an advertisement for DaVinci Resolve. The capabilities and tools in Shotcut are great for what I need it to do.

And NO, color.io cannot do what I just showed in the demo images - at least not with ease. That’s why I had to go back to DaVinci Resolve to do the color grading.

[PhLo]

My guess is that there is some way to create color-specific masks that could target granular color ranges in Shotcut to color grade specific colors to achieve comparable results, like with an HSL mask or something… but it would not be quite as easy as in Resolve, since they have a built-in solution. But if someone wants to answer with “Here’s how to do something like Qualifiers in Shotcut,” feel free. No guarantee I’ll use that method, but others might have interest. I don’t recommend going to all that work though unless you are really bored!

For someone with a lot of time on their hands, making a bunch of videos comparing software would be interesting. For example, here’s how to achieve Goal X in DaVinci Resolve, and here’s how to achieve the same Goal X in Shotcut.

[shotcut]

@PhLo

My guess is that there is some way to create color-specific masks that could target granular color ranges in Shotcut to color grade specific colors to achieve comparable results

Mask: Chroma Key Video Filter

The video filters beginning with “Mask:” let you select a portion of the image or video in which to apply other video filters. There are a few different ones, and this one lets you choose the portion of the image by a color and a distance from the chosen color. [image] See the “Tip” above. To really make this work you add additional video filters that affect the selected color range followed by the Mask: Apply video filter, which combines every thing in between. So, the order of the filters is…

[PhLo]

That’s a cool and helpful tutorial with the filter stacks. One thing that would make masks more powerful in Shotcut would be to have multiple sliders for different attributes of color selection. A great example is selection by HSL (Hue Saturation Lightness - or Value). I find this to be the most useful and intuitive for getting super specific selections. I wish more programs had this option - like photo editors, video editors, OBS Studio, Raw Editors, and more. Anything with green screen or chromakey masking can benefit from HSL masks. With only a simple “distance,” “similarity” or “threshold” slider it is not possible to get as accurate of masks. But if there are sliders for each channel, then, for example, you can tell it to select ALL greens, whether dark greens or light greens using the L or V channel, and a wide range of saturation using the S channel, but only a very small range of hues (perhaps from just before cyan to the full area of greens, but not yellow) using the H channel. Sadly, surprisingly few magic wand / threshold / similar / distance sliders for color selections in any software implement this powerful feature.

As an example, here’s the qualifier panel in Resolve. You can select many different qualities of the color, rather than a single “distance” slider. HSL is just one of the modes. There are others as well, including RGB, luminance, and 3D. All these options make it much easier to select exactly the color ranges desired. Notice how I have selected settings that would work well for a green screen - certain hues, saturations and luminance. The triangles are how much it smooths or falls off from full white selected to black not selected (aka grayscale), which is awesome, and each side can be adjusted independently.

The closer a color gets to black or white, generally the less saturation it has. So a single slider has a harder time isolating selections in a particular hue, and other similar limitations when only one slider exists.

The only critique I have of the DaVinci Resolve equivalent is that it’s called “Qualifier” which is very techy sounding. But I guess it has some sense to it, just not the word I would think to use.

[PhLo]

Oh, now I see Shotcut essentially has what I was referring to, just not as graphical in its presentation. I just had to look around. I might play with this in the future.

That slope shape might allow even more fine-tuned control. Interesting.

The Key Spill filters look interesting too. Lots of options, which is always good imo.

[shotcut]

@PhLo

multiple sliders for different attributes of color selection

You can by adding a Chroma Key: Advanced after the Mask: Chroma Key. I chose to integrate the simple chroma key with the mask filter because I think it is the more popular choice. I could easily add a Mask: Advanced Chroma Key.

A mask filter does two things: take a snapshot of the incoming frame and change the alpha channel. You can add other filters that either replace or refine the alpha channel. See also the Operation parameter in Chroma Key: Advanced. That lets you add more than one Chroma Key: Advanced filter to combine keys. You can also add an Alpha Channel: Adjust and Key Spill filters. And temporarily add in Alpha Channel: View to help see what is going on. You can include as many non-alpha oriented filters before the Mask: Apply. And save your filter stack as a named Set. The big limitations are A) you can only use one Mask: Apply at a time, and B) performance when using many filters.

[PhLo]

Nice, seems quite powerful. I’ll probably crash it if I use it too heavily with my old GPU, but my projects are pretty simple, so it would probably be fine. I don’t do Hollywood productions with tons of tracks and filters. Mostly just color grading at this point in time.

If I ever go back and use Shotcut for color grading instead of exporting a LUT from DaVinci Resolve to use in Shotcut like I am currently, I’ll try to make a video to share for the benefit of others on how to do those advanced adjustments. I’ve come up with a pretty magical LUT though, so I might not ever go back and redo it. Except my eyes seem to keep getting more attuned, so I see more problems even with a grade I formerly thought was perfect.

It’s really fun to spend so much time on a LUT that it is absolutely better than the color science of the camera though. If I released my LUT, I’m fairly confident anyone using my camera would choose it over the manufacturer supplied LUT from Log footage. It looks WAY better with my LUT. Fun stuff.