Infer LUT confusion

[Claire_Marie]

Hiya, 

I'm really struggling to wrap my head around the 'infer LUT' adjustment. I trialed a plugin that I eventually decided wasn't worth the money. There was 1 filter on it that I love though, so I am trying to emulate it. 

I would've thought this is where the Infer LUT option would help me out here, but I am really struggling to make it work. 

Here is one of my photos untouched:

Here is the filter I love using: 

Here is another untouched photo:

Here is the infer LUT adjustment using the two first photos:

 

So what is going on here? Can anyone suggestion another way of doing this? I have been going round in circles trying to emulate this filter. If this isn't what infer LUT is for, then what is it for?

Thanks in advance!  

 

 

[Lee D]

Using Inter Lut will compare the source file and an adjusted one, the process will mimic the adjusted one as close as it can but results will vary. You may want to try mimicking the colour grading from one image to another as it may give better results. We don't have a tutorial on this but there are some available on YouTube like this one.

[kirkt]

@Claire_Marie - As @Lee D notes, the Infer LUT operation compares the before and after color of an image and tries to reverse engineer the color in the after image based on the before image.  Some images that are used in the Infer LUT operation may not have a very wide variety of tone or color represented in them, so when inferring a LUT from them, the inferred LUT only captures part of the toning (the toning restricted to the colors present in the image).  One way that LUTs are stored in a graphical format is to use a before and after version of a special color image called an Identity (ungraded, neutral) HALD CLUT (color lookup table) image like this one:

As you can see, this special image is essentially a grid of colors with a wide range of tonal and hue variation.  Copy this HALD image and run it through your filter and then use the before and after versions of it as your Infer LUT base images.  The Identity HALD image contains a lot of colors and will capture your filter's color transform fully.  As with all LUTs, the HALD images need to be in the color space of the image you are editing for the color transform of the LUT to work as expected.

Here is  link to a page of technical LUTs which includes the original HALD image I posted here:

https://3dlutcreator.com/3d-lut-creator---materials-and-luts.html

For example, here is a webpage that contains a link to several HALD CLUTs that capture color transforms for several film simulations.  You can use these in AP to apply a film look to your image with a LUT adjustment layer and the Infer LUT feature.

https://patdavid.net/2015/03/film-emulation-in-rawtherapee.html

Kirk

[R C-R]

16 hours ago, kirkt said:

For example, here is a webpage that contains a link to several HALD CLUTs that capture color transforms for several film simulations.  You can use these in AP to apply a film look to your image with a LUT adjustment layer and the Infer LUT feature.

https://patdavid.net/2015/03/film-emulation-in-rawtherapee.html

Wow!!! Thank you so much for your detailed explanation & the links. This works great in AP!

To make it super simple to use these inferred LUTs, I realized that they can be applied in macros. At first, I could not figure out how to give the LUT adjustment layer a descriptive name as part of the macro when nested as a child layer, but setting the Assistant manager option "Adding adjustment layer to selection" to "Add adjustment as new layer" solved that.

Since the inferred LUT is 'baked' into the macro, it isn't even necessary to have the contents of the HaldCLUT folder available after the macro is saved to the Library. Since that folder is around 420 MB, to save space on the startup drive, it could be offloaded to thumb drive or whatever.

👍👍👍

[Claire_Marie]

Thank you so much for your replies, the HALD image has now worked almost perfectly on many of my photos, I just have to tweak a few little things but that's all fine in my book. Again, thank you for your time. I am really enjoying getting to know both Affinity Photo and Affinity Designer. 

[R C-R]

On 7/16/2020 at 9:31 AM, kirkt said:

One way that LUTs are stored in a graphical format is to use a before and after version of a special color image called an Identity (ungraded, neutral) HALD CLUT (color lookup table) image like this one

FWIW, http://www.quelsolaar.com/technology/clut.html includes a lot of detailed info about HALD CLUT's, the identity versions, & so on that I found very helpful in understanding what they are & how they can be used.

Also, mostly for my own amusement I created nine macros based on the resources from the Pat David.net web page HaldCLUT download, using AP's "Infer LUT..." with the Hald_CLUT_Identity_12.tif as the source file & one of the CreativePack-1pngs as the adjusted one. Each of them includes 5 steps like this one for the FallColors.png:

Each of the macros executes very quickly even on my old iMac. Because they start with a Deselect Layers step, were recorded with the Assistant Manager set to add adjustments as new layers, & end with a "Move Inside" step (automatically applied during the rename step), they should work well with any AP file as long as the topmost layer is a pixel one like the Background layer you get by default when opening a photo file. 

Together, these 10 files from the download alone require about 10 MB of file space. The nine macros exported to a single .afmacros Affinity library file uses only about 400 KB of file space. Because everything is 'baked' into the .afmacros file, this would be a great way to share macros like these with other AP users, who would not have to download the large HaldCLUT file to use them.

I would like to upload my Creative 1 LUTs.afmacros file here or in the Resources forum, but I won't do that without first checking with Pat David to make sure it is within the scope of the license for his work. Accordingly, I am going to contact him through his 'about' link & refer to this post to explain what I want to do.

[Alfred]

Slightly off topic, does anyone here know what ‘Hald’ refers to?