RawTherapee Dev version bugs

I don’t know if this is the right place to mention bugs for Dev appimage versions of RawTherapee, but there are a couple I’ve noticed when working with digitized colour negatives.

  1. The spot white balance tool doesn’t work properly. After using the Film Negative module so the image is now positive, clicking with the spot white balance tool puts a strong orange mask over the image. It’s still a positive image, but with an orange mask. On the other hand the “pick white balance spot” in the film negative module works properly. It should be noted that in ART, the spot white balance works properly.
  2. Again, working with colour negatives, the white balance temperature slider works backwards in RT dev version, but normally in ART.

Ping @rom9

Hi @troodon :slight_smile:

Yes, i know, it’s a bit confusing, but this is actually the intended behaviour.

The new version is a major rework; the film negative tool now works after white balance, so the regular WB sliders work backwards.
This was a necessary change in order to support non-raw images (tiffs from scanners, for example), and also has the advantage to speed up processing, because we don’t have to repeat the demosaic step on each filmneg adjustment.

With this version, you should first apply the “Film Negative” bundled processing profile (available in the drop-down menu), then set the regular WB tool to the color temperature of the backlight that you’re using, and not touch it ever again.
All subsequent color balance adjustments should be done via the new color balance sliders and “Pick” button built into the film neg tool.

You can also choose whether to perform inversion before or after input color profile conversion, via the “Inversion color space” dropdown. Choosing “Input color space” should give results very similar to the old version, while selecting “Working color space” should be more color-accurate (although this depends on many variables…)

Let me know what you think about the results :wink:

This looks promising. Do you still need to use the “pick neutral spots” or is “pick white balance spot” sufficient for that? Sometimes with historical negatives it’s hard enough to find a single neutral spot let alone two. I’m still experimenting with negatives I’ve previously converted with the old way, or with ART and I think I should be able to match the results.

@rom9 I just tried the new process you described on some “difficult” negatives that I couldn’t get looking right before. Here’s an example. It was quite easy to get good colour, despite the image having no neutral grays. This is from a 6x7 Fuji negative. HS2_3720 lowres

1 Like

@rom9, I am LOVING the new film negative tool! This is from a 6x6 cm colour negative my father took back in the 1960s at The Banff Centre for Fine Arts.

2 Likes

Thanks, i’m glad you like it :slight_smile:

Your old pictures are always awesome. This negative was exposed nearly 60 years ago, and still retain an outstanding image quality!

You need to use both, although sometimes the default Red ratio / Blue ratio values might be ok.

Also note that in this version, there is an additional usability trick: when you use the “pick white balance spot” button, the selected spot will be balanced to neutral gray and it will act as an “anchor point” for the exponent/ratio settings. Meaning that, when you adjust the red and blue ratios manually, the selected white balance spot will stay gray.
This way, after you’ve picked the white balance spot:

  • if you see that darker areas have a red color cast, you know that you need to raise the “Red ratio” value
  • if you see that brighter areas have a blue color cast, you know that you need to lower the “Blue ratio” value
  • … and so on …

So, this can serve as a guideline when you don’t have the two neutral spots available, and you have to manually adjust the ratio sliders.

Thanks for the white balance tips. I’ll watch for that when I’m processing.

I’ve been trying to find negatives that do have two usable neutral spots and saving that profile to use on other negatives with the same or similar film type. By copying and pasting that profile the colour needs only minor adjustment for the other negatives.

One little irritant that I’d like to see changed is the default “lock ratio” setting for cropping an image. I never want the ratio locked and it just adds another step to the process to unlock it, then go back to the film negative tool.

As all settings in RT, you can override it be creating an own profile (pp3) and use it as your default profile.

2 Likes

Hmm, actually i could even include the FixedRatio=false setting in the bundled “Film Negative” processing profile :thinking:
This way, the Lock Ratio flag would be automatically disabled for everyone when dealing with negatives.
@heckflosse what do you think, should i add this to the profile and push it to dev? :wink:

1 Like

I’m not Ingo, but for negatives it makes sense to have the ratio unlocked I think.

2 Likes

Done (sorry for the delay) :

With the next dev build, applying the Film Negative bundled profile should automatically disable the “Lock ratio” flag :slight_smile:

Thanks, that’s much appreciated.