■This is the testing ground for the color conversion I’ve been wanting.
■The description for each LoRA is provided within its respective tab.
■If you're new to Kontext, try installing it using the instructions at the URL below.
It's well-documented and easy to set up.
https://docs.comfy.org/tutorials/flux/flux-1-kontext-dev
■I used AI Toolkit to train this LoRA.
If you're interested in training, the developer has provided a tutorial at the URL below — give it a try!
Description
Training Data (3.9 MB):natron_log_to_HDR_sample
■This LoRA converts normal images into low-contrast images similar to ARRI_LogC4.
This has made it possible to turn regular images into HDR images.
■This is a bit more specialized, so color conversion is required.
If you simply wish to reduce overexposure or color saturation, please use the ACEScg_look LoRA instead.
■Please use the prompt suggested in the trigger tag—this is the same prompt I used when training the LoRA.
■When converting from ARRI_LogC4 to linear sRGB or ACEScg, the following OCIO configuration supports it:
studio-config-v1.0.0_aces-v1.3_ocio-v2.1.ocio
It can be downloaded here:
https://github.com/AcademySoftwareFoundation/OpenColorIO-Config-ACES/releases/tag/v1.0.0
■Any software that supports OCIO should be able to handle the conversion.
The following software are good candidates:
After Effects, DaVinci Resolve, Natron, Nuke
In some cases, it may also be possible in ComfyUI if OCIO support is enabled via an extension.
I have uploaded an example of the conversion done in Natron in the sample images, so please use it as a reference.
■However, this is not a perfect ARRI_LogC4 conversion, and negative values often appear in the shadows.
If the artifacts are unacceptable, setting the mix to around 0.6 during linear conversion will retain some of the low contrast from the log, resulting in better balance. This will also preserve richer gradation when performing tone mapping.
As a side note, in Natron the OCIO colorspace mix doesn’t seem to work, so I used merge-copy mix 0.4 to partially blend the log image and get the same result.
For the OCIO display node, I set gain to 1.5 to match sRGB brightness, but you can also do this by adding a Grade node above it—adjust as you prefer.
If you have any questions about the conversion, feel free to ask; I’ll share any info I can, though it may take some time.
FAQ
Comments (3)
yeah but how do i get the sRGB_viewtone_map Result? :D
Thanks for your interest!
It’s a bit technical, so apologies if it feels complex, but using the OCIO settings from this link in any OCIO-compatible software should produce the same result:
https://civitai.com/images/93781205
Free options include DaVinci Resolve and Natron (I can share a Natron workflow scene if helpful). I’ll add it later—though ComfyUI might also work, I haven’t tested it.
I’ve also posted a more detailed explanation here:
https://www.reddit.com/r/StableDiffusion/comments/1mobup9/created_an_arri_logc4_conversion_lora_and_a/
If you try an OCIO-compatible program and run into issues, feel free to ask—I’ll do my best to share where the settings are, even if it takes some time.
Kind of a lot of work for very little benefit if the starting image is just clamped rec709. Would need to use one of the custom nodes that lets you save to an hdr format like exr as the starting image, and hope it's not doing something dumb like just saving an 8bit or 16bit integer internal render to float, doing nothing but bloat it out. but even then, if you're going to be using this in Resolve or Natron or Nuke (or even jumping through Adobe's hoops in AE) and you have an exr you can just use the native workflow to go to Log if you want to work log, and apply a tonemap.
Details
Files
Available On (1 platform)
Same model published on other platforms. May have additional downloads or version variants.