Panasonic G9 underexposure and Darktable

va3pinner

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Greetings -
I may need to post this in the Panny thread, but I'll start here.
I use Darktable 3.4 as my primary RAW processor because I am a Linux user. I also toy around with RawTherapee. I am not real conversant with post processing, but I eventually do get results I like.

I use DT in the Scene Referred mode, and when I load my images, the histogram always shows them as underexposed. Every subject, even though the Filmic module boosts exposure by 0.75 to mimic what we see with the in camera JPG images, if I go by the DT histogram, I need to boost my exposures bu up to 1.5 stops to fill up the histogram from end to end, or more depending on subject.

Today I was playing around with some flower photos, testing the zebra settings (set at 95%) to see how far I could go before blowing highlights . Shooting manual, I was able to increased my exposures up to 1.5 stops just to see what I would get. Histogram in the camera looked fine. For 'normal exposure' - it was evenly spaced. For ETTR exposures, it was further to the right as expected. But when I loaded it into Darktable - Histogram showed underexposed.

So I loaded some of these RAW files into RawTherapee, and its histogram showed images much closer to 'properly' exposed. By that I mean the histogram reflected what I saw in camera - running nearly from edge to edge as I would expect.
Question is Why does DT histogram show my images as being "underexposed"?? even if I deliberately ETTR??
I don't know if its Darktable, the camera, or me (the most likely culprit!!)
Any ideas? and Thanks!
Bruce
 
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Darmok N Jalad

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I believe it's just how each camera records the exposures, and each model does it a bit differently. You just need to create a base curve for the G9 and auto-apply it when importing your RAWs. I'd attach an importable sample of mine, but I don't believe the forum accepts it as an attachment. Here's what the curve looks like. From there, you can start doing the rest of your edits.
 

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va3pinner

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I believe it's just how each camera records the exposures, and each model does it a bit differently. You just need to create a base curve for the G9 and auto-apply it when importing your RAWs. I'd attach an importable sample of mine, but I don't believe the forum accepts it as an attachment. Here's what the curve looks like. From there, you can start doing the rest of your edits.
thank you, I thought about that. The base curve for the G9 is available in DT, but it is disabled for use by the new Filmic RGB. I may need to contact them and find out what's going on.
thanks for supplying your setup!
 

BDR-529

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Darktable release notes mention that in scene-referred mode exposure must be cranked up by 1 stops or more.

It's also a "feature" not a bug and you can set a default value in the exposure module (I believe it's set to +0,5 stops by default but it's not enough)
 

Dinobe

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Make sure that the histogram profile is set to linear Rec2020 RGB

2021-06-14 12_21_32-Window.png
Subscribe to see EXIF info for this image (if available)
 

speedy

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Also, make sure that the iDynamic feature is turned off in camera. This causes the camera to underexpose the raw to preserve the highlights, & boosts shadows during the in camera conversion. It results in what looks like under exposed raw files when you go to develop them in another converter, as what you see through the EVF is a jpeg representation of the in camera converted raw. If that makes sense.
And set the picture style to standard, or natural, even when shooting raw, to prevent the camera applying exposure compensations to satisfy the jpeg output.
 

Dinobe

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You just need to create a base curve for the G9 and auto-apply it when importing your RAWs
The scene referred workflow does not use the base curve, but uses the Filmic module and adds +0,5ev to the exposure by default.
This might not be enough for your G9. I don't know how much would need to be added to the exposure module to 'emulate' the G9.
 
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va3pinner

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Darktable release notes mention that in scene-referred mode exposure must be cranked up by 1 stops or more.

It's also a "feature" not a bug and you can set a default value in the exposure module (I believe it's set to +0,5 stops by default but it's not enough)
Yes I did see that while doing research, but I wonder what that will do when I expose ETTR. My understanding is, when exposing ETTR, we bring the exposure down in PP to deal preserve the shadows, avoid unnecessary noise etc.
 

va3pinner

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Definitely have to watch i.Dynamic, it tries to preserve shadow detail, but you get underexposed-looking images. I think it's on AUTO by default, and I think it works on RAW files and not just the JPGs.
that is something I did not realize, and will make sure it stays off
 

va3pinner

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Note to all of you - thanks for the assistance! and I apologize for the very late replies. I did not mean to be rude, but a lot of life got in the way in the last few weeks!
This was well covered in here by your truly and a guy who used to frequent here that was a DT guru named @junkyardsparkle

https://www.mu-43.com/threads/tone-...-on-setup-and-adjustment.101719/#post-1277602

I've stopped using base curve, as recommended, and now use the Tone Equalizer and Filmic RGB
Dont know how to ask this question properly - but
I usually don't mess with the default settings in Filmic RGB. I just make sure it is turned on and leave it alone. And I have not fooled much at all with Tone Equalizer. What settings/presets/processes in either one of these that you find useful, or could be a good starting point for me to learn?
Thanks
 

Brownie

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Note to all of you - thanks for the assistance! and I apologize for the very late replies. I did not mean to be rude, but a lot of life got in the way in the last few weeks!

Dont know how to ask this question properly - but
I usually don't mess with the default settings in Filmic RGB. I just make sure it is turned on and leave it alone. And I have not fooled much at all with Tone Equalizer. What settings/presets/processes in either one of these that you find useful, or could be a good starting point for me to learn?
Thanks
Filmic is to me an enigma. Sometimes it's fantastic, sometimes a bust. I try it after adjusting tone equalizer, but am just as likely to turn it back off.

For the Tone Equalizer, I suggest 2 things:

1st, watch the Bruce Williams You-Tube videos on this module. They will help a lot.

2nd, open the module, and click the menu options. Then try the different soft, medium, and hard presets. I used to adjust them all manually, but have only recently learned to try those first. Usually it's just a tweak here or there after that.

But do watch the videos first. He has an excellent series for DT.
 

va3pinner

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Filmic is to me an enigma. Sometimes it's fantastic, sometimes a bust. I try it after adjusting tone equalizer, but am just as likely to turn it back off.

For the Tone Equalizer, I suggest 2 things:

1st, watch the Bruce Williams You-Tube videos on this module. They will help a lot.

2nd, open the module, and click the menu options. Then try the different soft, medium, and hard presets. I used to adjust them all manually, but have only recently learned to try those first. Usually it's just a tweak here or there after that.

But do watch the videos first. He has an excellent series for DT.
Thanks I am familiar with Bruce Williams vids, and definitely need to watch this one again. And for several of the modules, I do use many of the presets, I find them very helpful as starting points, and often just leave it alone after applying them. i should say I kind of gravitate toward presets anyway. My first digital PP experience was with LightZone, and that was all presets. Now I'm beginning to ferret out the options in presets. I'll have to post some samples of my tweaks in another thread, just to get some more experienced eyes on my work. I really don't have as much time to spend on PP that I would like, so I keep my work flow simple. this business of having underexposed looking RAW images was puzzling. Thanks for the help.
 

Brownie

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Thanks I am familiar with Bruce Williams vids, and definitely need to watch this one again. And for several of the modules, I do use many of the presets, I find them very helpful as starting points, and often just leave it alone after applying them. i should say I kind of gravitate toward presets anyway. My first digital PP experience was with LightZone, and that was all presets. Now I'm beginning to ferret out the options in presets. I'll have to post some samples of my tweaks in another thread, just to get some more experienced eyes on my work. I really don't have as much time to spend on PP that I would like, so I keep my work flow simple. this business of having underexposed looking RAW images was puzzling. Thanks for the help.
Some presets are really good and some not so much. The Sharpen preset in Contrast Equalizer over-sharpens quite a bit. I reduced it to 60% and saved it as a new preset. It's a much better starting point.

On a recent outing processing was (from memory) Lens Correction > Tone Equalizer > Local Contrast > Contrast Equalizer.

Other modules applied as needed included Basic, Crop (if needed, mostly for leveling if I goofed), Filmic, Exposure. These were fairly rare and the vast majority of 100 or so shots were the four I mentioned.
 

Dinobe

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My 2 cents: DT comes with more than 70 modules, you only need about 10 and mostly you only need to tinker with 4-5 of these 10

My order of processing
1. Apply lens correction - off by default, just switch on
2. Crop and Rotate - off by default, crop and straighten your image
3. Exposure - on by default, use the lightbulb to assess exposure
4. Filmic - on by default, raise and/or lower black and white point, a rough approximation is good enough, fine tuning is done in other modules, worth checking is the color science in the option tab. By default this is RGB power norm, I sometimes prefer to set this to 'none' and set the saturation in the colour balance
5. Local Contrast - off by default, I have a made a preset 'clarity' (detail 130%, highlights 0%, shadows 0%, midtone range 0,5)
6. Color Balance - off by default, set contrast, saturation, midtones, shadows highlights here. - loop back to filmic
If you have set your white point too high in filmic, you might get burnt out areas in the color balance module, go back to filmic and adjust.

And that's it, this should work in 80% of the cases.

Important to understand is that DT can have multiple instances of the same module. So by having multiple Exposure modules I can set the overall exposure, a second instance to darken the sky, a third to brighten the midground..
Almost all modules can by combined with drawn, parametric and drawn & parametric masks making really fine tuned effects possible.

Extra's worth checking/doing
7. Chromatic aberrations - off by default, if you see purple edges in high contrast areas
8. Defringing - off by default - off by default, helps to remove those halos at high contrast edges
9. Contrast equaliser - off default, I use the "sharpen" preset, by turn it really down as the preset is far too strong
10. Highlight reconstruction - on by default, change to 'reconstruct in LcH' and lower the treshhold to reconstruct clipped skies, use with care, doesn't always work
11. Color zones, off by default, - can help to 'color grade'
12. Tone Equaliser, off by default, - I use this to dodge and burn, but with care, it's easy overcooked. I've seen people use this as a tone curve replacement. Interesting idea.
 
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Brownie

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12. Tone Equaliser, off by default, - I use this to dodge and burn, but with care, it's easy overcooked. I've seen people use this as a tone curve replacement. Interesting idea.
That's the whole idea. I never use the curve anymore. If you click on advanced it after applying the mask it's a horizontal curve, nothing more. The difference is the ability to place your cursor over the area you want to change instead of playing with a curve, and even changing how the curve interacts with itself. Much more effective.

Masking on DT is amazing. It's perfect to pull back an overexposed sky. Using a drawn/parametric mask and feathering you can get right down to detail fast, without spending a lot of time trying to outline everything perfectly. And the ability to copy that same mask to any other module is fantastic.
 

va3pinner

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Thank you both!
Dinobe - that is very similar to the modules i use. I have pretty much stuck with the modules only available in workflow scene referred just to learn the new system, and keep it simple. In addition to the modules you suggest,I also use Haze removal I find that really useful. In the Contrast Equalizer, I tend to use the Denoise and Sharpen pre set. In But you will make me take a closer look at my stuff. May be oversharpened but we can fix that eh?
Actually I'd like your opinion, I have things posted on Filckr under the username Va3Pinner. if any really make you gag, let me know!

Brownie - Masking is something I just started playing with, and even with my so-far crude results, I can really see the potential.
 

va3pinner

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For a moment I thought DT 3.6 fixed this, but I was editing photos from my older G2 and Olympus E-510. DT reflected the histogram that I saw in camera, so it must be using their base curve??
When I load the G9 images, DT shows underexposed by at least 1.5 stops. I just dont get it. I may go into settings and load the base curve anyway and tweak Filmic as I go.
 
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