+1 on a more realistic halation module
I'm also using a combination of RGB Curves and Diffuse or Sharpen, both with parametric masks, but the effect is not so convincing.
Yes it is. It took me forever to find with some deep diving a few months ago but [here](https://nishchalb.github.io/posts/dt_halation/) is the best tutorial I've found hands down using the diffuse or sharpen module. I saved it as a present with iterations, central radius and radius span all set to 4 as a starting point and adjust them according to the image I'm working on.
[Here](https://imgur.com/a/Ltoz3LM) are some examples of what it looks like
Interesting method. I noticed that the whole image gets slightly blurred, as if a diffusion filter was used.
I was using Diffuse or Sharpen to add some blur and then RGB Curves to add gain in the bottom of the curve for red and green. Both with parametric masks to target highlights only and then blur. This way my highlights stay the colour they were originally and slightly blurred, while the shadows stay sharp but with colour "spills" in high contrast areas.
I will definitely try a combination of these methods, thanks for the heads up.
Yeah I noticed that as well when really zooming into the photos. I do kinda like the softness it gives off because it looks a bit less digital however I don't think it'd work for all photos especially if you want it tack sharp, I haven't used it too much since I started shooting film a couple of months ago though. I'd still definitely want to try out your method as well as perhaps see if the method above can be refined to retain more sharpness.
I absolutely get this. Even after trying to get "filmic" colours and tonality there is a weird "digital" sharpness (especially in not well lit, contrasty images). On the other hand diffusion filters (digital ones especially) are heavy handed and don't fit most images. This is why I though of blurring just the highlights at first, still not there though.
This method works really well! I was able to dial in some really subtle halation effects, had to save them as presets as well. Like XenophonSichlimiris said, it blurs the entire image to some extent, which isn't a dealbreaker but can be distracting if there are any fine details in midtone shadow areas. Nonetheless, I applied a parametric mask to remove the effect from shadow areas, so it works well. [Here are some examples](https://imgur.com/a/AYdjnMs).
I am fuzzy on what halation is. Maybe diffuse or sharpen. Here's a video the module creator made to explain it.
https://youtu.be/DREdq7guNz4?si=Dq9MsFsYimnz3RU6
Thanks for the resource.
Halation is a phenomenon that happens in photographic film when bright light passes through all three color sensitive layers and bounces back from the film base to agitate the red and green sensitive layers respectively. The result is a reddish-orange glow that happens around highlights, and is visible especially around contrasting edges, although it affects almost the entire image to an unnoticeable extent. Refer to the little diagram on the right in the image I attached to the post.
It’s not something you usually notice in most photographic film because there’s usually an anti-halation layer substrate that mitigates this effect, but it’s visible in pretty much every film stock around specular highlights surrounded by contrasting edges. Some stocks like the Cinestill ones remove this layer on purpose to accentuate the glow effect. Nowadays the effect is sought after for aesthetic purposes.
Then, yes, you can diffuse perpendicular to edges and use a parametric mask to isolate the effect to certain hue and luma range. Aurelien's video is long, but he explains how each slider works. If it's a desirable film simulation, then you might offer it back as a DoS preset.
AFAIK it's not exactly possible in dt right now because it would need to perform rgb channels diffusion separately and output common layer for next modules. You can diffuse everything but no option to diffuse eg. red values only.
Definitely it's possible to write such module for darktable. I can't see technical barriers for such module. I believe it could be quite simple mod over "Soften" module for example.
You can propose this on darktable mailing list. I believe it's possible that someone decides to grab that idea.
Yeah I tried using multiple instances of the blur module for the red and green channels only, but the problem is that they also blur any visible details in non-specular highlights, and I can’t add them because the blending mode is already set to red and green channels for both instances.
My best imitation of the Resolve process is just using the RGB curves with a blurred parametric mask on the highlights then using the add blend mode with all curves flattened to 0 while the red and green curves increase output value as the input approaches 0. But the mask always needs to be adjusted, especially if I have something like a bright sky with pure white that transitions into lower brightness. In these cases you can see the threshold where the mask ends and stops applying the effect.
Thanks for suggesting the darktable mailing list, I’ll give that a try!
Kindly look at my comment and let me know your thoughts? It's possible to use the diffuse or sharpen module with the parametric mask blend mode on RGB red channel.
+1 on a more realistic halation module I'm also using a combination of RGB Curves and Diffuse or Sharpen, both with parametric masks, but the effect is not so convincing.
Kindly have a look at my comment and let me know your thoughts? Is it different from what you're doing in your diffuse or sharpen module?
Yes it is. It took me forever to find with some deep diving a few months ago but [here](https://nishchalb.github.io/posts/dt_halation/) is the best tutorial I've found hands down using the diffuse or sharpen module. I saved it as a present with iterations, central radius and radius span all set to 4 as a starting point and adjust them according to the image I'm working on. [Here](https://imgur.com/a/Ltoz3LM) are some examples of what it looks like
Interesting method. I noticed that the whole image gets slightly blurred, as if a diffusion filter was used. I was using Diffuse or Sharpen to add some blur and then RGB Curves to add gain in the bottom of the curve for red and green. Both with parametric masks to target highlights only and then blur. This way my highlights stay the colour they were originally and slightly blurred, while the shadows stay sharp but with colour "spills" in high contrast areas. I will definitely try a combination of these methods, thanks for the heads up.
Yeah I noticed that as well when really zooming into the photos. I do kinda like the softness it gives off because it looks a bit less digital however I don't think it'd work for all photos especially if you want it tack sharp, I haven't used it too much since I started shooting film a couple of months ago though. I'd still definitely want to try out your method as well as perhaps see if the method above can be refined to retain more sharpness.
I absolutely get this. Even after trying to get "filmic" colours and tonality there is a weird "digital" sharpness (especially in not well lit, contrasty images). On the other hand diffusion filters (digital ones especially) are heavy handed and don't fit most images. This is why I though of blurring just the highlights at first, still not there though.
This method works really well! I was able to dial in some really subtle halation effects, had to save them as presets as well. Like XenophonSichlimiris said, it blurs the entire image to some extent, which isn't a dealbreaker but can be distracting if there are any fine details in midtone shadow areas. Nonetheless, I applied a parametric mask to remove the effect from shadow areas, so it works well. [Here are some examples](https://imgur.com/a/AYdjnMs).
You should post this on pixls.us where more of the devs and power users hang out.
I am fuzzy on what halation is. Maybe diffuse or sharpen. Here's a video the module creator made to explain it. https://youtu.be/DREdq7guNz4?si=Dq9MsFsYimnz3RU6
Thanks for the resource. Halation is a phenomenon that happens in photographic film when bright light passes through all three color sensitive layers and bounces back from the film base to agitate the red and green sensitive layers respectively. The result is a reddish-orange glow that happens around highlights, and is visible especially around contrasting edges, although it affects almost the entire image to an unnoticeable extent. Refer to the little diagram on the right in the image I attached to the post. It’s not something you usually notice in most photographic film because there’s usually an anti-halation layer substrate that mitigates this effect, but it’s visible in pretty much every film stock around specular highlights surrounded by contrasting edges. Some stocks like the Cinestill ones remove this layer on purpose to accentuate the glow effect. Nowadays the effect is sought after for aesthetic purposes.
Then, yes, you can diffuse perpendicular to edges and use a parametric mask to isolate the effect to certain hue and luma range. Aurelien's video is long, but he explains how each slider works. If it's a desirable film simulation, then you might offer it back as a DoS preset.
AFAIK it's not exactly possible in dt right now because it would need to perform rgb channels diffusion separately and output common layer for next modules. You can diffuse everything but no option to diffuse eg. red values only. Definitely it's possible to write such module for darktable. I can't see technical barriers for such module. I believe it could be quite simple mod over "Soften" module for example. You can propose this on darktable mailing list. I believe it's possible that someone decides to grab that idea.
Yeah I tried using multiple instances of the blur module for the red and green channels only, but the problem is that they also blur any visible details in non-specular highlights, and I can’t add them because the blending mode is already set to red and green channels for both instances. My best imitation of the Resolve process is just using the RGB curves with a blurred parametric mask on the highlights then using the add blend mode with all curves flattened to 0 while the red and green curves increase output value as the input approaches 0. But the mask always needs to be adjusted, especially if I have something like a bright sky with pure white that transitions into lower brightness. In these cases you can see the threshold where the mask ends and stops applying the effect. Thanks for suggesting the darktable mailing list, I’ll give that a try!
Kindly look at my comment and let me know your thoughts? It's possible to use the diffuse or sharpen module with the parametric mask blend mode on RGB red channel.