Flat field correction in Lightroom

[rdeloe]

I use an LCC frame with images created with the S-K APO Digitar 35/5.6 L-88. From time to time, flat field correction in Lightroom simply doesn't work. There's no obvious reason.

When this happens, I either fix the image with gradients, or run it through Raw Therapee, which works flawlessly. The problem with Raw Therapee is it makes a TIFF and I can no longer use my preferred camera matching profiles. I tried applying the profile and then exporting as DNG and as TIFF. Raw Therapee can read the DNG fine, but the adjustments are ignored, so that doesn't get me anywhere. Raw Therapee reads the TIFF with the adjustments applied without issue, but because it's no longer a RAW file, flat field correction is not available.

My guess is the flat field correction in Lightroom is just not a particularly good tool, and making it better isn't high on Adobe's list of things to do. But I thought I'd check just in case someone has a brilliant solution.

P.S. "Use Capture One" is not an answer I'm looking for.

 

[Bill_Evans]

What isn’t working? I’ve been do a bit more work / testing with my 907x 50C and I haven’t noticed it not working. But maybe I’m missing something. My typical approach is to take test shots to find the exposure that I like, maybe a bit over exposed. Then take an LCC shot. Then I take a 7 shot bracket with 1 stop increments. Then I WB the 8 images to be the same and Flat Field Correct all the images at once.

I’m pretty new to this idea, so I could, probably am, total screwing it up. But it does seem to work within the limits of the lenses I’m using.

 

[rdeloe]

Bill, it works most of the time. It's a very simple tool. Identify your image, and identify your LCC frame.

But then sometimes it simply doesn't work. By that I mean, I select the files, apply flat field correction from the menu, and .... nothing. There's no error message. It simply decides to not do it. The progress bar flashes by, and the original RAF is unchanged.

If you feel like trying, here are two files: https://drive.google.com/drive/folders/1ikowHrVQRvqpvfOdedLOdCvqHM_NsNEN?usp=sharing

I call this stunning composition "Messing around with swing while I'm waiting for the dryer to finish drying my load of laundry".

I'm using Lightroom 13.3 (the most recent update).

 

[Bill_Evans]

LOL, I like the "laundry study" effort. I agree it's quite weird. I get the same thing. I tried converting both files to dng first and then performed the Flat Field Correction. It did do something, and wrote out a new dng-2 file. But it's definitely not "corrected" the way I'm used to seeing with my CFV files. Odd. I've never had a file not correct without gettin an error. Usually because of extreme exposure differences.

 

[Bill_Evans]

Things are getting a bit better. I worked through the process again.

1) First converted everything to DNG.

LCC Image


Original converted to DNG.


And Flat-Field Converted DNG.


It's like Lightroom isn't seeing the RAF file as a format it can Flat-Field convert but can convert it do DNG. Odd. Not a great work around but not terrible.

Bill

 

[TimoK]

I use an LCC frame with images created with the S-K APO Digitar 35/5.6 L-88. From time to time, flat field correction in Lightroom simply doesn't work. There's no obvious reason.

When this happens, I either fix the image with gradients, or run it through Raw Therapee, which works flawlessly. The problem with Raw Therapee is it makes a TIFF and I can no longer use my preferred camera matching profiles. I tried applying the profile and then exporting as DNG and as TIFF. Raw Therapee can read the DNG fine, but the adjustments are ignored, so that doesn't get me anywhere. Raw Therapee reads the TIFF with the adjustments applied without issue, but because it's no longer a RAW file, flat field correction is not available.

My guess is the flat field correction in Lightroom is just not a particularly good tool, and making it better isn't high on Adobe's list of things to do. But I thought I'd check just in case someone has a brilliant solution.

P.S. "Use Capture One" is not an answer I'm looking for.

Why don't you apply your camera profile in RT? You can select a custom input profile ( .dcp or .icc ) at the color tab.



Therapee worked fine with your photo and the lcc file, but I did not see big difference between Adobe profile and RT's own one. Maybe your custom camera profiles in the "real world" photos makes more difference.



Edit. Bill's solution might work better when keeping you in LR.

 

[John Leathwick]

Rob, I've encountered this once where I had used an extreme shift and the correction frame went very close to straight black. Is it worth checking the brightness range of your uncorrectable light frames to see whether that gives you some clue. I wonder if LR doesn't know what to do when it encounters say a complete hard vignette.

-John

 

[rdeloe]

Rob, I've encountered this once where I had used an extreme shift and the correction frame went very close to straight black. Is it worth checking the brightness range of your uncorrectable light frames to see whether that gives you some clue. I wonder if LR doesn't know what to do when it encounters say a complete hard vignette.

-John

John, this is a different problem I've encountered when making large shifts that produce complete "hard" mechanical vignetting. It makes sense to me that this doesn't work because both the LCC and the original will be all black. In the samples I provided here, it's dark, but not black. I can correct the image with gradients that get it quite close to the LCC-corrected version.

 

[rdeloe]

Why don't you apply your camera profile in RT? You can select a custom input profile ( .dcp or .icc ) at the color tab.

I did not know that was possible! My experience with Raw Therapee was limited to flat field correction in emergencies... This worked well.

I use Color Fidelity's profiles for GFX because they give me a very neutral starting point that I like. I was able to apply the CF profile to the flat field corrected image in Raw Therapee.

See, this is why I come here! Thanks so much.

P.S. If anyone else wants to try this, the camera profiles are here in Windows: C:\Users\[User]\AppData\Roaming\Adobe\CameraRaw\CameraProfiles

 

[rdeloe]

Things are getting a bit better. I worked through the process again.

1) First converted everything to DNG.

It's like Lightroom isn't seeing the RAF file as a format it can Flat-Field convert but can convert it do DNG. Odd. Not a great work around but not terrible.

Bill

Bill, that worked perfectly! Thanks so much. This is the solution I was looking for because I don't have to leave Lightroom.

I've been using LR for many years, and I teach using the darned thing, but I've never previously had to convert a RAW file to DNG after import, so my eyes passed over that "Convert to DNG" option in the Library menu every time I opened it.

Interestingly, Adobe still has some work to do because in the catalogue, the flat field corrected image is displayed as uncorrected in the Library, including in Loupe view and Compare view, so it looks like it failed again. However, when I open the file in the Develop module, it has been corrected. Generating previews for the corrected file does not fix this, and neither does optimizing the catalogue and restarting. As soon as you apply a change in Develop, it shows properly in Library -- so this is a very minor glitch.

 

[rdeloe]

Update: Bill's technique (convert to DNG inside LR) has another advantage: exposure is better. When I flat field correct from RAFs, if it works, LR boosts exposure. It's easy enough to bring it back, but flat field from DNG doesn't seem to do this.

Also, the minor glitch I described is resolved if you do not embed a JPEG preview when converting to DNG and when flat field correcting. Uncheck that option, and everything works properly.

 

[Bill_Evans]

Rob,

Glad things are working better. I’ve also been a Lightroom user for quite some time and I like to keep my workflow inside the Adobe ecosystem If possible. And the convert to DNG isn’t really that big a deal and can be automated during import if one wants to go that route. I think Adobe would prefer we all use DNG, but I’ve alway preferred to keep my original RAW formats intact. You never know when there might be a better demosaicing option for the originals.

My biggest gripe with the Flat-Field Correction is Lightroom’s need to remove the originals from the Lightroom catalog. The are still in the hard drive folder which makes no sense. You either have to synchronize the folder to import them back or go into finder to delete them. Seems very cluttered. I tend to go the syncronizing route since I like to keep my original RAW, LCC shot and correct image together.

Bill

 

[Bill_Evans]

Interestingly, Adobe still has some work to do because in the catalogue, the flat field corrected image is displayed as uncorrected in the Library, including in Loupe view and Compare view, so it looks like it failed again

I’ve also noticed this apparently “glitch” and I’ve wondered if it has to do with Lightroom generating background previews. Eventually the loupe views do kick in when I do large batch edits. I’m not quite sure exactly what’s going on here but I’ve learned to always check edits in the develop module for the most updated image.

 

[rdeloe]

Rob,

Glad things are working better. I’ve also been a Lightroom user for quite some time and I like to keep my workflow inside the Adobe ecosystem If possible. And the convert to DNG isn’t really that big a deal and can be automated during import if one wants to go that route. I think Adobe would prefer we all use DNG, but I’ve alway preferred to keep my original RAW formats intact. You never know when there might be a better demosaicing option for the originals.

My biggest gripe with the Flat-Field Correction is Lightroom’s need to remove the originals from the Lightroom catalog. The are still in the hard drive folder which makes no sense. You either have to synchronize the folder to import them back or go into finder to delete them. Seems very cluttered. I tend to go the syncronizing route since I like to keep my original RAW, LCC shot and correct image together.

Bill

The whole flat field correction subsystem is kludgy. There's no reason to delete the RAW from the catalog. Like you, I sometimes want them both. I do what you do: synchronize the folder to bring back the RAW files I want. I'm just thrilled that I can stay inside LR, so thanks again!

 

[glaiben]

When I started using LCC's, LR flat field correction failed a couple of times. At the time, I experimented with various exposure settings for the LCC image. LR correction failed when the LCC overall exposure was too dark. Using a longer exposure, and hence a lighter image, solved my problem. I did not test whether it would work just by lightening the LCC image in post.

...gregg

 

[rdeloe]

When I started using LCC's, LR flat field correction failed a couple of times. At the time, I experimented with various exposure settings for the LCC image. LR correction failed when the LCC overall exposure was too dark. Using a longer exposure, and hence a lighter image, solved my problem. I did not test whether it would work just by lightening the LCC image in post.

...gregg

That does make sense, and when I started using LCC frames I had some underexposed ones that didn't work. But the LCC frames from this recent issue are not underexposed.

 

[SrMphoto]

I am having a lot of problems with LCC in LrC. In Adobe's tutorial (https://www.getdpi.com/forum/index.php?threads/adobe-dng-flatfield-lcc-for-lightroom.40584/), Adobe writes that it can apply batch corrections when properly ordered. Instead, it starts from the end, uses the previous image as LCC, and converts both LCC and non-LCC images. Has anyone solved that issue?
Also, when selecting an image and its LCC individually, it works most of the time, except that sometimes it converts the LCC frame using the non-LCC frame.
This is with Hasselblad 3FR files.
I know that one solution is to use Phocus instead of LrC.

 

[rdeloe]

I am having a lot of problems with LCC in LrC. In Adobe's tutorial (https://www.getdpi.com/forum/index.php?threads/adobe-dng-flatfield-lcc-for-lightroom.40584/), Adobe writes that it can apply batch corrections when properly ordered. Instead, it starts from the end, uses the previous image as LCC, and converts both LCC and non-LCC images. Has anyone solved that issue?
Also, when selecting an image and its LCC individually, it works most of the time, except that sometimes it converts the LCC frame using the non-LCC frame.
This is with Hasselblad 3FR files.
I know that one solution is to use Phocus instead of LrC.

Sigh. This is all very familiar. It was working fine throughout 2024, and then in recent updates what you're describing happened. Is it still doing it with the latest 14.2 update? I haven't checked. I've had the most success putting the image first and the LCC frame second.

 

[SrMphoto]

Sigh. This is all very familiar. It was working fine throughout 2024, and then in recent updates what you're describing happened. Is it still doing it with the latest 14.2 update? I haven't checked. I've had the most success putting the image first and the LCC frame second.

Yes, still broken with 14.2. Sadly, Adobe's LCC correction seems to be the most convenient. Unlike Phocus and C1, you do not need to create an LCC first. I tend to shoot one LCC after each shot (correcting vignetting), and I do not know which focal length, focus distance or aperture I used in order to be able to reuse the LCC frame.

 

[rdeloe]

Gah. I tried it again today. It's getting worse with every update! C'mon Adobe!