Highlight handling: simplified DNG vs. Full DNG behaviour is not the same

DxO PhotoLab
1

Hi everyone,

I had some difficulties with the highlight handling of some DNG exports (when full DNG option selected), so I tried to experiment to understand why.

The comparison is based on 2 DNG files from PhotoLab:

  • 0 correction selected (nothing)
  • Export A as simplified DNG (noise & optical correction only)
  • Export B as full DNG (all corrections)

I would have expected to have 2 exactly identical exports, but it’s not always the case.
To see the difference, you need a RAW file with clipped highlights.

→ Export A (simplified DNG) behaves exactly as the initial RAW.
If applying a -2 IL correction, for instance, you would get the same output with the RAW and the DNG (A).

→ In export B (full DNG) however, highlights seems to have been stepped down just a little bit.
You can see it in the histogram, comparing A and B.
You can also see with the same -2 IL correction that the behaviour is completely different:

exemple|683x500
(left: simplified DNG - right: full DNG)

This is quite surprising, as no correction was selected.
I’m not sure which choice is the best (in can depend on the situation) but I think the difference should be made explicit: when processing the DNGs, export A and B require completely different highlight settings.

If you copy/paste the settings from the RAW to the Full DNG, the first impression would be that highlight details is very low.
When understanding which choice has been made, it’s easier to apply the correct settings.

In a real case, this means that for a RAW where you want only optical & noise corrections, you have the choice, selecting full or simplied DNG.
If you want to add, let’s say, a little bit of Lighting, however, your only choice is Full DNG, so you’ll get the highlights modification.

2

Are you sure no corrections were selected? Did you disable the effects of whatever startup preset you have set in preferences by using the No Corrections preset? I tried to recreate this issue on a couple of images but was unable to see any difference and the histogram looked identical for both DNGs. I’m using the Windows 10 version of PhotoLab 4…

Mark

3

“Export B = all corrections” obviously includes DxO’s standard preset – and Smart Lighting.

4

“All corrections” is just the choice of output.
All tools were unselected in both outputs, of course.
(And I never use dxo standard preset anyway).

The difference can be seen in lightroom, I didn’t try to reopen the dng with photolab. I’ll try it tomorrow.
I’ll try with some other raw software (like rawtherapee).

You need an image with burned highlights, otherwise no difference between A and B.
I’ll add a raw sample to the discussion.

5

Here is a sample image (I cannot add A & B exports are the filesize is too high).
Test.ORF (18,1 Mo)

Once again, “no correction” for both exports, just A=simplified DNG, B=DNG.

In Lightroom, the histograms are different and the files behave very differently when trying to recover highlights (A is the same as RAW, B is different)

In DxO, the difference is lower, but still there.
For instance, if we set exposure to -2, we can easily see the difference in the histogram. Export B doesn’t have anything near the right limit.
We still have A=RAW, B=different (burned highlights are toned down).