New Flat-Field Correction DNG should not remove/replace the original RAW in the catalogue

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I was shocked by the new Flat-Field Correction feature removing my RAW image from the catalogue.

"You can then use Flat-Field Correction in Lightroom Classic to automatically detect and analyze the calibration frame and remove the light falloff and colour cast from the corresponding regular photo."

Great, thought I might try it out and see if the Flat-Field Correction can remove the orange colour cast from a film negative that I've photographed in RAW.

I selected a photo of the blank leader part of the film as the calibration image and then selected another film negative RAW image to be corrected, which also had a virtual copy (not selected).

Ran the Flat-Field Correction.

To my horror, my original NEF image became a DNG and so did the virtual copy!

This isn't in the User Guide section on Flat-Field Correction. I had to find out from Laura Shoe's description of the Flat-Field Correction that this is how it's been designed.

This is a very bad design decision Adobe and very poor documentation to not mention that it will remove images from the catalogue.

I think this needs to be fixed and quickly.

The Flat-Field Correction DNG should only be added as a new image to the catalogue, like other DNG's created by Lightroom. This is how it should be. Software developers shouldn't be making the decision to remove images from the catalogue. We the users make that decision.

Anyway, my experiment with using Flat-Field Correction to remove the colour negative orange cast didn't work. The Flat-Field Correction DNG hardly looked any different to the original.

Since I don't appear to have any real lens shading or optical colour cast problems with my current equipment, it looks like this is another new Lightroom feature that I won't be using.

Ending on a positive note, the new Texture Adjustment is very welcome and useful.


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Anthony Blackett

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Posted 2 months ago

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Andrew Rodney

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This isn't in the User Guide section on Flat-Field Correction. 

It's outlined here;
https://helpx.adobe.com/lightroom-classic/help/flat-field-correction.html
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Anthony Blackett

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That's where I looked and I can't find any mention of removing/replacing the original RAW in the catalogue, only the option to delete it from disc.
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Christian Fürst

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Hi, Antony, I may be wrong, but I was under the impression that Adobe will ask you at te start of the process, whether you wanted to keep the original. Okay, may it would be a better idea to automatically keep the file and let the photographer decide if he/she wants LR to delete it....
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Anthony Blackett

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Lr doesn't delete the original RAW file from disc, unless that is the option you choose from the Flat-Field Correction diaolog.

It does, however, remove the original RAW from the catalogue, replacing it with the DNG.

It actually 'looks' like it replaces the RAW root file in the catalogue with the DNG. That would expain why the virtual copy became a DNG too. Without Adobe telling us, and they won't, more digging in the catalogue would be needed to find out.
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Simon Chen, Principal Computer Scientist

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Unless you override the setting to "Delete originals after successful correction", the originals are still kept in on the disk next to the result corrected DNG. This works similarly as the Convert to DNG command. Under the hood, the flat-field correction does not change the raw pixel values, it is working similarly as in-camera lens corrections for some camera models -- working non-destructively.


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Anthony Blackett

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Hi Simon,

I do understand that the original RAW is not deleted from disk, unless specifically deleted using the provided option. Therefore, it can be reimported if required, but I shouldn't have to do this.

If I do a Flat-Field Correction on a RAW image and find it hasn't done what I wanted, I would delete it from the disk. I would then need to re-import my RAW image and redo metadata, key wording and any Develop adjustments That I've made, and possibly to virtual copies as well. To avoid this I would need to either backup my catalogue just in case or export my images as a catalogue before the correction is applied so that I could import my originals again as they were. Much simpler for users' workflow to have the Flat-Field Correction DNG added to the catalogue.

I don't see that the Flat-Field Correction DNG should work so similarly to the Convert to DNG.

As I see it, the specific purpose of Convert to DNG is to replace the proprietary RAW image with a DNG and essentially they are equivalent.

Flat-Field Correction is creating a new DNG, yes in a similar way, but I see it as a different image to the original and that is why I think it should be added to the catalogue, just like the Enhance Details DNG.

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Todd Shaner, Champion

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Given most users have very little experience with Flat Field corrections I would suspect they would want to see the original edited raw file next to the Flat Filed converted DNG file for a comparison. Is there some way to do this without having to reimport the file or Synchronize Folders and the Sync settings to gain that capability? Unless I'm overlooking something this seems like an oversight from a real-world user perspective.

Simply offering the option to NOT Remove the raw file allows comparing the original next to the converted file AND the ability to keep the raw file in the catalog for future use.


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Anthony Blackett

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Hi Todd,

I had also thought of that, but didn't want to suggest it because I do think we shouldn't have to do it that way. I don't think the "Delete originals..." option should be there either. It's easy to delete later. Just create the Flat-Field Correction DNG as new image in the catalogue. Save everyone a lot of hassles.

The Enhanced Details DNG doesn't replace the original, neither should the Flat-Field Correction DNG.

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Laura Shoe, Champion

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I have to agree with Anthony on this one. I think people are expecting this to work the same as Enhance Details and HDR and Panorama merges.  I understand that you're being consistent with Copy as DNG, but Copy as DNG doesn't change the appearance of the image, so there's no reason to keep the original in the catalog. With FFC, users want to be able to compare before and after and then make a decision on whether to keep the original without having to go find it in Finder/Explorer.  Todd's preference would be fine, as long as the default is to leave the image in the catalog.
(Edited)
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Todd Shaner, Champion

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I don't think the "Delete originals..." option should be there either.
Conceptually Flat Field correction can be looked at as application of a Lens Profile. If you normally convert to DNG on import with Lens Profiles enabled ( I do) then it makes sense to offer this option. Flat Field correction provides better Vignetting control since it applies both luminance and color temperature correction across the image and you have the Lens Profile controls available to make changes. It's a little unclear to me what the Lens Profile Vignetting control uses for correction. Setting it to 0 with a Flat Field corrected DNG looks like some correction is still being applied.


As Simon Chen said, "Under the hood, the flat-field correction does not change the raw pixel values, it is working similarly as in-camera lens corrections for some camera models -- working non-destructively." This begs the question of why not also offer a checkbox in the Lens Profile panel to enable/disable Flat Field correction. You then have the option at any time to recreate the original raw file state for a "comparison" or to reapply Flat Field correction using a different Calibration image. In fact creating the Calibration image file may be the biggest challenge to properly using the Flat Field feature. Scene referred lighting can cause uneven illumination and color temperature across the reference calibration image and make the corrected Flat Field DNG file worse than the original raw file. ERGO-The need to have "compare" capability!
I suspect there are more potential issues with using this feature, but this is enough for now. Consider yourself warned and do NOT delete your raw image files until you are 100% confident all is well with your Flat Field DNG files! Peace!
(Edited)
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Anthony Blackett

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Fair enough Todd, and as always, very well explained. It would be helpful if Adobe were more forthcoming in explaining this new feature in more detail and give some better examples.

I haven't quite worked out what this "automatically detects ..." means yet:

"Lightroom Classic automatically detects the interleaving calibration frames, applies the flat-field correction to the corresponding regular photos..."

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Todd Shaner, Champion

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I haven't quite worked out what this "automatically detects ..." means yet:
There may already be an issue with this "automatic detection" as the OP at the below link is experiencing.
https://forums.adobe.com/message/11081323#11081323
He's trying to correct astrophotgraphy image files, which are obviously filled with large areas of black sky. The Flat Field converter may be detecting the the sky shot as a 2nd Calibration image file and simply closing without creating a DNG file. I've asked him to try the same Calibration file with a normal image file and see if it works.
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Peter Horstink

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I have tried just that. It works great with a regular photo, where usually the lens profile correction works good enough. A night sky is a different story and this is where flat fields could really shine. However that doesn't work because the software does not recognize it as a regular photo and will not correct it unfortunately. Would be nice if you could manually select it as a regular photo.