combing areas from two DNG’s pre-Lightroom processing

[Rip321]

Am I missing a way to splice together sections of two DNG files and then run Lightroom Noise Reduction and Lightroom Presets on the combined DNG?

I tried masking in open eyes from one DNG over blinking eyes in another DNG in Photoshop in 32 bit mode and saving to a TIFF file, but the TIFF file has already lost a lot of detail when opened again in Lightroom.

Thanks!

[dj_paige]

"Splice together sections of two DNG files" is not a feature of Lightroom Classic. This has to be done in Photoshop.

[Rip321]

Thanks.  I'd prefer to make my edits to the DNG before running Lightroom Denoise and Lightroom Masks.

If Photoshop can't edit a DNG for processing in Lightroom, what software can?

[dj_paige]

Thanks.  I'd prefer to make my edits to the DNG before running Lightroom Denoise and Lightroom Masks.

If Photoshop can't edit a DNG for processing in Lightroom, what software can?

By @Rip321

I never said Photoshop can't edit a DNG for processing in Lightroom. I'm not sure what you are trying to say.

[Rip321]

Great.  Thanks.  How can I save a document as a DNG in Photoshop?

The #1 search result in this forum says it's impossible.

"Why can't photoshop save an image to a DNG? Since Adobe is promoting DNG, this should be a no-brainer for a person to be able to save an image from the program to a DNG."

"Why should Photoshop be able to save images it does not support."

https://community.adobe.com/t5/photoshop-ecosystem-discussions/export-or-save-as-dng/m-p/13099644

So, back to my original question.  I'd like to edit a DNG from two source DNG files, and then run Lightroom Denoise, Lightroom Masking, and Lightroom Presets on the edited DNG file.

What's the correct workflow? 

Can I open both files in Photoshop in 32bit mode, make my edits, merge the layers, and save the document as a DNG for processing in Lightroom?

Thanks again.

[dj_paige]

I was responding to your statement: "If Photoshop can't edit a DNG for processing in Lightroom, what software can?" and of course Photoshop can EDIT a DNG and save it as a TIF or PSD or JPG for processing in Lightroom".

Now you switch to "save an image as DNG" which is different, and you have already found the answer.

Perhaps you need to describe your problem from the beginning and provide more detail, rather than assume DNGs are the solution.

[Rip321]

As stated in my original post:

I tried masking in open eyes from one DNG over blinking eyes in another DNG in Photoshop in 32 bit mode and saving to a TIFF file, but the TIFF file has already lost a lot of detail when opened again in Lightroom.

The TIFF file opened in Lightrooom doesn't look anything like the orginial DNG files, and Lightroom says Denoise is not available for this file format.

What's the correct workflow for editing a DNG and processing it with Lightroom Denoise, Lightroom Masks, and Lightroom Presets?

Thanks again.

[Rob_Cullen]

If I may 'nose in' with some comments-

I tried masking in open eyes from one DNG over blinking eyes in another DNG in Photoshop in 32 bit mode and saving to a TIFF file, but the TIFF file has already lost a lot of detail when opened again in Lightroom.

If the DNG file is a RAW file, then when you edit-in Photoshop it must be rendered to an RGB demozaiced image. It is no longer RAW. Photoshop cannot 'Save' an image as RAW data, it must be an RGB file-type (TIF, PSD, JPG, etc).

So Photoshop cannot save a RAW DNG file, meaning you cannot then use Lightroom Denoise.

Photoshop is the only way you can transfer rendererd pixels from one image to another. Again it must be an RGB file-type (TIF, PSD, JPG, etc).

The TIFF file opened in Lightrooom doesn't look anything like the orginial DNG files, and Lightroom says Denoise is not available for this file format.

In what way "doesn't look"? If you save as an uncompressed TIF it will contain all the pixel data of a rendered RAW file. If colors, saturation, visual look, change, then there must be something in the workflow making these changes.

Lightroom Denoise does not 'make' a RAW DNG file. It makes a rendered RGB file in a DNG 'Wrapper'.

"DNG" does not necessarily mean RAW.!

What's the correct workflow for editing a DNG and processing it with Lightroom Denoise, Lightroom Masks, and Lightroom Presets?

Lightroom Denoise will only work with a RAW file (be that a RAW Camera file converted to DNG, or a RAW Camera file as NEF, CR3, etc). 

So I see your workflow options as-

1) Apply Lr Denoise to both original RAW files > DNGs, Combine the DNG images in Photoshop (to TIF), Do final edits to the TIF in LrC.

2) FIrst Combine the images in Photoshop (to TIF), and accept that Lightroom Denoise is not available. Use other noise reduction methods.

[Rip321]

Thanks for your help.

How can I tell if a DNG file contains RAW data or RGB data?

This article from the Adobe blog says Lightroom Denoise produces a raw file:

"After multiplying and adding up a gazillion numbers, your computer will produce a new raw file in the Digital Negative (DNG) format"

https://blog.adobe.com/en/publish/2023/04/18/denoise-demystified

The only difference in the DNG metadata of the original and the Denoise DNG is the compatibility field, and both have Mosaic Data: Yes.

Also, there must be something I don’t understand about working with 32bit TIFF files in Lightroom.  If I open the original DNG in Photoshop, save it to a 32bit TIFF without any adjustments, and then open it in Lightroom without any adjustments, the histogram goes from this:

To this:

Thanks again.

[Rob_Cullen]

"..both have Mosaic Data: Yes."- No.

As I understand the explanations of Denoise from various sources- I believe the Blog article you linked to be misleading by using "raw" in the statement "....produce a new raw file".

Another quote from the same Blog article-

"..our models are designed and trained to perform both demosaicing and denoising in a single step..."  ie. the DNG is not mosaic data (as from the camera).

"How can I tell if a DNG file contains RAW data or RGB data?"

I don't have an answer. I believe it was Rikk Flohr (Adobe Staff) that suggested that the Lr Denoise function embedded the original raw data within a resulting DNG file, but there is no way (currently) of extracting the raw data from the denoised DNG.

I will let someone else answer the TIF histogram changes.

[Rip321]

Thanks.

If the metadata of the DNG file created by Lightroom Denoise is inaccurate, and the file has, in fact, been converted to RGB, where can I find the RGB bit-depth in Lightroom?

Also, does running Lightroom Denoise eliminate the benefits of working with RAW files in Lightroom to adjust Exposure, Whites, Highlights, Blacks, Shadows, Texture, Clarity, Dehaze, Sharpness, HSL, etc?

Is the correct workflow to export the DNG's generated by Lightroom Denoise to Photoshop directly without any Lightroom adjustments?

Also, I'd still like to understand how to open a 32bit TIFF file in Lightroom without the image becoming washed out and overexposed.

Thanks again.

[D Fosse]

The denoised dng is still linear with the extended 12-14 stop dynamic range that allows, as opposed to a gamma-encoded "finished" image. So you still have the editing headroom of the original raw file. You do not want to send directly to Photoshop unadjusted. You'll lose the possibility for highlight recovery, and you will likely get some unrecoverable channel clipping.

Don't know about the 32 bit TIFF, beyond the fact that any 32 bit file needs tone mapping because it can contain data below black and above white (as you see it on screen). What you see on screen is a limited window into the full data. But I don't know how Lightroom handles that. Presumably you would just use the normal tonal controls.

[Rip321]

Thanks.

Now I'm totally confused.  Has Lightroom Denoise converted the DNG to RGB or not?

How can I open a 32bit TIFF in Lightroom without the image becomming overexposed and washed out?

[D Fosse]

It is demosaiced, but still linear. So it's linear RGB.

Think of it as a partly processed raw file. The crucial point for editing headroom is that it's still linear and not yet encoded into an output color space like sRGB, Adobe RGB or ProPhoto. It still contains more data than can be represented in a standard color space.

This is the standard output from all of  Lightroom/ACRs special functions that produce a new standalone file separate from the original raw file (Denoise, Super Resolution, Panorama).

It also conforms to the basic raw paradigm that it is read only and cannot be overwritten. So for all practical purposes, it's still a raw file.

[Rip321]

Thanks for the detailed explanation.

Is there any software that can combine areas of either the original Lightroom conversion DNG or the linear RGB DNG generated by Lightroom Denoise and preserve the headroom in the image for Lightroom Presets?

I thought opening a DNG in Photoshop and saving it to a 32 bit TIF might preserve the headroom for Lightroom Presets, but this file is overexposed, washed out, and the histogram is altered in inscrutable ways when opened in Lightroom.

I'd like to understand where is the earliest point in this workflow I can combine areas from two images:

RAW conversion to DNG on Lightroom import, Lightroom Denoise, Lightroom Presets, Photoshop

Perhaps some other software can provide an earlier editing step than Lightroom or Photoshop.

Thanks again.

[D Fosse]

You need to denoise the individual files first. Then you can merge to panorama.

Denoise only works on mosaic raw files directly from the camera sensor. Panorama, however, will accept demosaiced files.

So the order is given. Except that you need to denoise first, this is as early as it gets. The resulting merged file is, as I said above, for all practical purposes a raw file and can be treated as such.

Personally, I prefer to merge in Photoshop, but not for any technical quality reasons. It's because you have vastly more control over the process in Photoshop. You can decide which frame is the "anchor" that the other frames align to, and you can control which parts to include and exclude in each frame. You can also compensate for perspective stretching of the corners, and the inevitable quality loss that comes with that stretching, by scaling down the anchor frame so that you don't get significant upsampling in the corners.

None of this is possible in Lightroom, there you basically push the button and take whatever you get. But this obviously requires very careful processing in Lightroom first, because you can't recover highlights, and you can't easily get back clipped channels.

[Per Berntsen]

It is demosaiced, but still linear. So it's linear RGB.

By @D Fosse

LrC reports denoised DNGs as having mosaic data.

Using Edit in Photoshop opens them directly in PS with no dialog, and LrC settings are applied.

They also open in Raw Digger.

So they seem to be true raw files as far as I can tell.

[D Fosse]

@Per Berntsen 

OK - reporting "mosaic data yes" actually appears to be a new bug. It does that for all files now. But it's not correct. I checked with Super Resolution too, and that too says "mosaic data yes". I know for a fact that super resolution is demosaiced linear RGB dngs.

But the other part, opening without a dialog in Photoshop, that's expected. A linear RGB dng is for all practical purposes still a raw file. It behaves like a raw file and it still contains 14 stops of dynamic range. RGB doesn't mean it's fully processed and encoded into a color space; it just means demosaiced.

Can others check this too?

This is super resolution:

It's easy to check this. We know that Denoise doesn't work on demosaiced files. And Denoise does not work on this Super Resolution file above.

EDIT to add: Here's Eric Chan in "Denoise demystified":

"Denoise uses machine learning (...) designed and trained to perform both demosaicing and denoising in a single step" (my emphasis).

[ZappaJul]

As others have explained, you can't splice RAW files in LR, but a correctly set up RAW file will look identical in .tif or .psd format once opened in PS. I'd suggest this workflow:

1. Set LR external editing prefs to Adobe 98 col space / 64bit / save to .tif or .psd / high res (most people choose 300ppi, but 360ppi better in many printed scenarios).
2. Process both DNG RAWs in LR > use Reference View to ensure colour consistency > DeNoise on both > R-click > Open as Layers in PS > ensure open eyes layer on top > auto (or manually) align layers so eyes match > add inverted Mask to open eyes layer > brush in open eyes > sharpen if required (use seperate merged layer) > save > automatically reappears in LR (useful for project management / exporting multiple files in uniform format).
3. You might want to consider a coding system to easily differentiate between PS edited files saved back to LR, and LR RAWs. (I do this by tagging blue in LR and auto-renaming external edits to denote app used, eg: name_original_file_number-PS.tif for files externally edited in Photoshop, or name_original_file_number-TPZ.tif for files edited in Topaz.