[SOLVED]: Darktable HDR : help wanted

So, I shoot a stack of 5 images with DJI Inspire 1 drone with X3 camera. I used AEB 5 that automatically captures a stack of 5 images with different exposures.

Here are the raw files:
https://drive.google.com/drive/folders/1Oec8SjmgBRmHUPnAwKqfoAioHQ_rr_vq?usp=sharing

In Lightroom I get a perfect HDR merge with which I can work with. Lightroom also has some masking levels which it applies so that there are no underexposed or overexposed parts so that result looks very natural.
In Darktable there’s a completely different story.
What does Darktable do when it creates an HDR?

The merge is greatly underexposed, it’s completely black. When I added multiple exposure modules to bring the exposure up, I get to see a bad merge with many artifacts and areas where the detail is lost so it ends up looking very flat.

So my question is, am I doing something wrong?
What result can you get with the raw files I provided?
Is there anyone here who works with HDR in Darktable and is it possible to have a normal workflow for HDR?

So here is the image right after the HDR merge with it’s sidecar:


DJI_0096-hdr.dng.xmp (9.2 KB)

Here is after I applied many exposure modules and a few other ones:


DJI_0096-hdr_01.dng.xmp (9.2 KB)

And finally here is how it looks if I apply perspective correction, everything goes to hell:


DJI_0096-hdr_02.dng.xmp (9.6 KB)

In any case, it’s terrible.

You need to apply some tone mapping!

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It kind of gives me the same results but very desaturated, I still have to apply multiple exposure modules. The detail seems to be lost (like on the road, stone walls etc.) still but I can only gets sharpened or removed even more.

Also applying haze removal gives me these weird square artefacts that you can see on the cars.

I’m still scouring the web and documentation but I’ll do a comparison with Lightroom and give a few more questions if I still don’t understand how to get better results in Darktable.

I’m also thinking it might be the lack of auto alignment or deghosting although images don’t seem to need aligning anyway but idk.

As someone who tried to improve one of darktable’s tonemapping algorithms (their exposure fusion algorithm is great in theory and is based on one of the fundamental foundations of Google’s HDR+ algorithm used in their Pixel phones, but the implementation is severely broken), I’d suggest:

Try HDRMerge for merging the raw DNGs into a single DNG with reduced shadow noise.
Use RawTherapee to do the tonemapping of the result - I’ve been VERY pleasantly surprised by the performance of the Fattal '02 algorithm (RT’s Dynamic Range Compression tool).

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I don’t think you need to merge these files into an HDR. The dynamic range is covered completely by DJI_0099.DNG. That is probably why you’re having such issues giving the merged image a HDR-treatment.

Here is the single shot with some light processing:


DJI_0099.DNG.xmp (4.3 KB)

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I know I don’t need to merge this particular example but more often than not I need to merge it.

  • When working with drone images near the sea/ocean for example and you want to see the beach and the seabed.
    If you expose averagely then the beach will be overexposed whatever you try to do and the sea will be dark blue.
    If you overexpose you’ll get to see what’s on the bottom of the sea but then you’ve lost the entire land etc etc etc… hdr rules until I figure something else out :confused:

  • I also do a lot of HDR for real estate, like when I want the interior to be lit as if the sun was inside the room but still want the perfect exposure for the view outside the windows etc.

Since I work with Canon 77D i rely A LOT on HDR to cover the poor dynamic range of my camera and to get professional looking results and but still save time.

HDR saves me time b/c I just do a mask for the windows and everything is done inside the Lightroom and I don’t need to edit multiple images and go into Gimp etc. I’d do it in Gimp but I’d be shooting myself in the foot b/c Gimp is destructive and the more changes you make the worse the image quality gets etc.

Now, Lightroom has imo good HDR but masking is 1000% better in Darktable so I wanna move b/c it could potentially save me hours and hours of masking work.

@Entropy512 HDRMerge seems to do the job very nicely and RT seems to be importing it well without any tone mapping. Thank you for the advice!

Darktable fails me again tho, I may have discovered a bug for real now:

HDRMerged dng imported in RawTherapee without any adjustments, just amazing:

HDRMerged dng imported in Darktable without any adjustments, oh my, oh my (should I report this as a bug?):

Also here is the HDRMerged dng:
https://drive.google.com/open?id=1UMih8E4W8BMNM9IvoPpN69ffiCvKyRlA

@paperdigits
Just to show you what I’m talking about, this is the result that went to the client:

Basically I’m looking for a way to do this in Darktable or possibly RawTherapee so I can ditch LR b/c that’s the one and only app that I need Windows for, everything else is on Linux and everything else seems to work good enough or better in Darktable except hdr x|

Does this help you?

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If you want example xmp files, post a photo that needs an HDR treatment.

By default RawTherapee has the exposure module enabled, which makes auto adjustments. Darktable has no such thing. For a fair comparison, reset the exposure module in RawTherapee.

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Agreed.

hdrmerge and then darktable 2.7.

But I didn’t tweaked the exposure. Only used the tone equalizer relight preset and then a tone curve.

@paperdigits you’re right, once I’ve set tone curve to linear it was pretty much the same brightness. However I was not referring to that being an issue in that example but rather the countless artifacts in the image.

Take another look but expand the image:

You see these dots all over the image? Almost looks like dead and hot pixels.

Enable and tweak the hot pixels module

EDIT: it worked with me this way:
image

@gadolf

No way, those are really hot pixels??!

Worked like a charm tho!

Humm, kind of hard for now.

For a quick and dirty edit, I’d try to use exposure + filmic + tone curve. In filmic, start with a preset, then tweak the middle grey luminance. Also, if you get strange colors, disable preserve chroma, and readjust extreme luminance saturation to your taste.
This is from memory.

Oh boy!! It’s perfect <33
That’s almost exactly what you get with LR after merging I say almost b/c this also seems to be a bit better!

Just with hot pixels like you said and tone curve that’s what RT had by default like @paperdigits pointed out. Also the HDRMerge was the key here.

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No, they are not. The RawTherapee output does not show this artifacts and (I checked) no hot/dead pixels were fixed.

@heckflosse should I make a bug report?

Yes, seems to be a bug.

Alright, will do!