GXR raw and jpeg in digikam

[nicolabotta]

I have a GXR since about three weeks and I'm still experimenting with the camera settings and with a new 50mm module.

One aspect I'd like to ask some advice about ist the relationship between raw (DNG) and JPG files. I'm new to raw shooting so I might have misunderstood something elementary.

I have been shooting in RAW [F], AUTO white balance, STANDARD colors mainly in M oder A mode and spot EM. The intention was to use DNG for storage and postprocessing and JPG for preview.

Now I'm not sure this approach actually works for me: I see significant differences in brightness between DNG and JPG files in digikam 1.2.0. In most cases DNG files appear to be significantly brighter than the correspondent JPG preview, in particular for long exposures.

I'm reporting three examples. In each example the first picture has been obtained by importing the GXR DNG file in digikam with standard settings and rescaling to 800 pixels. The second one has been obtained by rescaling the GXR JPG file to 800 pixels. Here is a first example:









I do not know how the files would look like with different camera and digikam import settings or in Aperture or Lightroom. With my settings it seems I cannot really rely on the JPG preview for judging the exposure of the raw file.

Initially i thought the DNG files would consistently appear more exposed than the corresponding JPG files. Here is another example, this time from the A12 module:









However, I have meanwhile realized that this is not always the case. Here's a final example in which the DNG file come out slightly less exposed than the corresponding JPG:









Any idea how to setup the camera and/or the digikam program to get consistent exposure in DNG and JPG files ? Thanks, Nicola

 

[Johannes Leitner]

Hello Nicola,

this is most likely caused by the "Auto Brightness" setting in the RAW-Import-Dialog.
Uncheck this setting in the RAW-Decoding-Configuration menu.

Kind regards.
gio

 

[nicolabotta]

Hello Nicola,

this is most likely caused by the "Auto Brightness" setting in the RAW-Import-Dialog.
Uncheck this setting in the RAW-Decoding-Configuration menu.

Kind regards.
gio

Thanks Gio, you are right the problem is caused by digikam settings: on a Mac with a default viewer the DNG files look as bright as the JPG files. "Auto Brightness", however, is unchecked. All values of the RAW-Decoding-Configuration menu are set to default, libraw is 0.8.5. Best, Nicola

 

[A Subset]

Hi Nicola,

Without meaning to sound condescending, it appears that you don't quite understand what RAW is all about. Basically what a RAW file is is the complete and uninterpreted data from the camera chip. I understand that this may not be technically always true, but for the sake of discussion we may consider it to be true. The JPG, on the other hand, has taken this RAW data and run it through a processor to attempt to create the most pleasing image from the data available. It then compresses this image data into a JPG file and discards all the rest of the data that it didn't "think" was needed.

So the simple answer is that if you just want clean and simple pretty pictures without a lot of work, stick with the JPGs. However, if you would like to perhaps have more control over the interpretation of the image, and are willing to spend the time and (maybe) money to do so, go with RAW. But if you choose the latter path you will also have to invest the energy into learning how to use your image processing software to get the kind of image you want from among the almost limitless choices that are available with the great amount of data that a RAW file holds.

Of course one option is that you can shoot with the camera set to capture BOTH the JPG and the RAW, and then you can just stick the RAW files away on your disk for sometime in the future when you might have more interest in "tweaking" them to get a different interpretation of the image.

Hope maybe this is of some help. Mostly you should just use the camera and enjoy it and if you have the desire your will learn more over time. There is no right or wrong, it's only what you want to get from it.

• A.

 

[nicolabotta]

Johannes, a short update:

• checking / unchecking auto-brightness does not seem to have any effect on a picture's preview (embedded jpeg preview) but it has a significant effect on DNG imports (Edit -> Import).

• there are still huge differences between in-camera JPGs and the jpegs obtained from the raw files via digikam.

best,
Nicola

 

[Pangloss]

Hi Nicola,

Like you, I frequently use Digikam and perhaps I can give you a few hints about how it works with DNG (raw) files.

Actually the significant differences in brightness you see in your DNG vs JPG files is attributable to a Digikam setting for auto exposure correction, i.e. Digikam will automatically "fix" the exposure for underexposed or overexposed pictures when developing raw files. You can obviously turn off this setting.

Personally however I have found that RawTherapee (and in particular the latest 4.0 version) does a much better job developing DNG files, compared to Digikam.

RT has superior noise reduction algorithms and more flexible controls over a wider selection of parameters, so specially for high ISO or noisy images, RT does a consistently better job than Digikam. The downside is that the learning curve for RawTherapee is much steeper and I found it rather intimidating at first. I wouldn't hesitate to recommend it for "difficult" postprocessing jobs, though.

Also I often combine RT's raw processing with Digikam for filters, framing etc and sometimes also with Gimp for editing.
This trio of free apps (RT, DigiKam and Gimp) is very convenient and flexible.
--
Andrew
Novice photographer

 

[Pangloss]

Nicola,

Johannes, a short update:

• checking / unchecking auto-brightness does not seem to have any effect on a picture's preview (embedded jpeg preview) but it has a significant effect on DNG imports (Edit -> Import).

This is because the preview is based on the exposure-corrected low resolution JPEG which is embedded in the DNG file.

• there are still huge differences between in-camera JPGs and the jpegs obtained from the raw files via digikam.

Oh yes. In many cases I prefer the JPEGs from the GXR rather than anything I manage to come up with in postprocessing using RT/Digikam/Gimp. Ricoh has really fine-tuned the JPEG engine in the GXR, in fact each GXR module has its own fine-tuned JPEG engine.

This is one of the reasons I always shoot in raw + JPEG fine mode. For 95% of my photos I don't even have to deal with raw developing, I use the out-of-camera JPEGs from the GXR.

Cheers,
--
Andrew
Novice photographer

 

[nicolabotta]

Hi Nicola,

Like you, I frequently use Digikam and perhaps I can give you a few hints about how it works with DNG (raw) files.

Actually the significant differences in brightness you see in your DNG vs JPG files is attributable to a Digikam setting for auto exposure correction, i.e. Digikam will automatically "fix" the exposure for underexposed or overexposed pictures when developing raw files. You can obviously turn off this setting.

How can I turn off auto exposure correction in digikam 1.2.0 ?

Personally however I have found that RawTherapee (and in particular the latest 4.0 version) does a much better job developing DNG files, compared to Digikam.

RT has superior noise reduction algorithms and more flexible controls over a wider selection of parameters, so specially for high ISO or noisy images, RT does a consistently better job than Digikam. The downside is that the learning curve for RawTherapee is much steeper and I found it rather intimidating at first. I wouldn't hesitate to recommend it for "difficult" postprocessing jobs, though.

Also I often combine RT's raw processing with Digikam for filters, framing etc and sometimes also with Gimp for editing.
This trio of free apps (RT, DigiKam and Gimp) is very convenient and flexible.

Thanks a lot, I'll check RT !

--
Andrew
Novice photographer

 

[nicolabotta]

Johannes, a short update:

• checking / unchecking auto-brightness does not seem to have any effect on a picture's preview (embedded jpeg preview) but it has a significant effect on DNG imports (Edit -> Import).

This is because the preview is based on the exposure-corrected low resolution JPEG which is embedded in the DNG file.

I understand. But what is the rationale for the embedded JPEG to be exposure-wise so different from the in-camera JPEG ?

• there are still huge differences between in-camera JPGs and the jpegs obtained from the raw files via digikam.

Oh yes. In many cases I prefer the JPEGs from the GXR rather than anything I manage to come up with in postprocessing using RT/Digikam/Gimp. Ricoh has really fine-tuned the JPEG engine in the GXR, in fact each GXR module has its own fine-tuned JPEG engine.

This is one of the reasons I always shoot in raw + JPEG fine mode. For 95% of my photos I don't even have to deal with raw developing, I use the out-of-camera JPEGs from the GXR.

Thanks! I'm actually fine with the out-of-camera JPEGs and I'm happy to learn that one can rely on the GXR JPEG engine. The only thing I did find disturbing was that DNGs and JPEGs look very similar in a standard preview under Mac OS X and quite different in a digikam preview. But as far as this is a digikam problem and not a problem of my GXR settings I do not really care.

Cheers,
--
Andrew
Novice photographer

 

[Pangloss]

Hi Nicola,

Hi Nicola,

Like you, I frequently use Digikam and perhaps I can give you a few hints about how it works with DNG (raw) files.

Actually the significant differences in brightness you see in your DNG vs JPG files is attributable to a Digikam setting for auto exposure correction, i.e. Digikam will automatically "fix" the exposure for underexposed or overexposed pictures when developing raw files. You can obviously turn off this setting.

How can I turn off auto exposure correction in digikam 1.2.0 ?
...

You probably configured it when you first used Digikam, here:





and here:





Obviously you can change these settings at any time to suit your workflow/habits. Regarding the automatic exposure correction, it is the "Auto Brightness" box which you have already found and unchecked!
--
Andrew
Novice photographer

 

[Collie Camp]

Hi,

with my A12 28mm and 50mm Modules the DNGs taken with an ISO Speed of 100 aka low Iso are 1 Stop brighter than the ones taken at the original ISO speeds of the GXR. The sensor base speed seems to be ISO 200 and ISO 100 was intro ducted later via firmware update i think.

Anyway using Apple Aperture, the ISO100 DNGs are all 1 stop brighter than the JPGs and all other DNGs taken at other ISO speeds.

regards

 

[nicolabotta]

Pangloss,

your last mail has solved the problem, thanks a lot !

It is meanwhile clear that this is a digikam (1.2.0 ?) problem, not a GXR one. Thus, sorry for being off-topic, I wanted to be sure it was not an issue related with my GXR settings.

Unfortunately digikam's interpretation of configuration settings is quite bizarre: the options set in

Settings -> Configure digiKam -> RAW Decoder Settings (1)

have no bearing on the default values used for opening RAW files in the editor when

"Use the Raw import tool to adjust corrections manually" (2)

is checked. They set the RAW import default values only for the case in which RAW files are opened automatically that is, when (2) is unchecked.

When (2) is checked, no matter what the Auto Brightness settings are in (1), Auto Brightness is per default on and has to be unchecked manually in the import menu.

This is annoying (one extra click) but that's it. I might try to upgrade to 1.9.0 to see if the problem has been corrected, I came across an old bug report from 2010 on this issue.

Best,
Nicola

 

[nicolabotta]

Thanks Collie,

I haven't tried low ISO on my A12 yet. As explained in my previous post, the problem I have reported is due to a digikam settings bug or feature. Not a GXR settings issue, as far as I understand.

Best,
Nicola

Hi,

with my A12 28mm and 50mm Modules the DNGs taken with an ISO Speed of 100 aka low Iso are 1 Stop brighter than the ones taken at the original ISO speeds of the GXR. The sensor base speed seems to be ISO 200 and ISO 100 was intro ducted later via firmware update i think.

Anyway using Apple Aperture, the ISO100 DNGs are all 1 stop brighter than the JPGs and all other DNGs taken at other ISO speeds.

regards

 

[Collie Camp]

OH - OK. An Auto exposure thing.

Was just looking at picture 1 and three. Picture one, with the big difference is an ISO 100, right?

I think it is a firmware bug, that ISO 100 is now possible, but only the jpg shows the right exposure, the dng doesn´t, at least in Apple Aperture 3. Maybe Ricoh didn´t set the right marker in the DNG...or it is an apple aperture bug.

 

[nicolabotta]

OH - OK. An Auto exposure thing.

Was just looking at picture 1 and three. Picture one, with the big difference is an ISO 100, right?

Yes, picture 1 is from the S10 module at ISO 100. Pictures 2 and 3 are both from the A12 50mm module at ISO 200.

I think it is a firmware bug, that ISO 100 is now possible, but only the jpg shows the right exposure, the dng doesn´t, at least in Apple Aperture 3. Maybe Ricoh didn´t set the right marker in the DNG...or it is an apple aperture bug.

That should not be difficult to find out: just take a picture with ISO low and one with ISO 200 and compare the difference between the DNG and the JPG in both cases.

 

[nicolabotta]

Hi Nicola,

Like you, I frequently use Digikam and perhaps I can give you a few hints about how it works with DNG (raw) files.

Actually the significant differences in brightness you see in your DNG vs JPG files is attributable to a Digikam setting for auto exposure correction, i.e. Digikam will automatically "fix" the exposure for underexposed or overexposed pictures when developing raw files. You can obviously turn off this setting.

Personally however I have found that RawTherapee (and in particular the latest 4.0 version) does a much better job developing DNG files, compared to Digikam.

RT has superior noise reduction algorithms and more flexible controls over a wider selection of parameters, so specially for high ISO or noisy images, RT does a consistently better job than Digikam. The downside is that the learning curve for RawTherapee is much steeper and I found it rather intimidating at first. I wouldn't hesitate to recommend it for "difficult" postprocessing jobs, though.

I gave RT a short try. DNG previews and JPG are very consistent in RT, at least with standard settings. In this regard it seems to do a much better job than digikam. Thanks !

Also I often combine RT's raw processing with Digikam for filters, framing etc and sometimes also with Gimp for editing.
This trio of free apps (RT, DigiKam and Gimp) is very convenient and flexible.
--
Andrew
Novice photographer

 

[nicolabotta]

Hi Nicola,

Without meaning to sound condescending, it appears that you don't quite understand what RAW is all about. Basically what a RAW file is is the complete and uninterpreted data from the camera chip. I understand that this may not be technically always true, but for the sake of discussion we may consider it to be true. The JPG, on the other hand, has taken this RAW data and run it through a processor to attempt to create the most pleasing image from the data available. It then compresses this image data into a JPG file and discards all the rest of the data that it didn't "think" was needed.

So the simple answer is that if you just want clean and simple pretty pictures without a lot of work, stick with the JPGs. However, if you would like to perhaps have more control over the interpretation of the image, and are willing to spend the time and (maybe) money to do so, go with RAW. But if you choose the latter path you will also have to invest the energy into learning how to use your image processing software to get the kind of image you want from among the almost limitless choices that are available with the great amount of data that a RAW file holds.

Of course one option is that you can shoot with the camera set to capture BOTH the JPG and the RAW, and then you can just stick the RAW files away on your disk for sometime in the future when you might have more interest in "tweaking" them to get a different interpretation of the image.

A., thanks for your reply and explanations !

In fact I have started shooting RAW and JPG. I'm aware of the data overload and of the workflow related with storing and post-processing raw files.

At the moment I'm also not interested in learning more about post-processing. I just was disturbed by the fact that the GXR JPGs and DNGs looked so different in digikam previews.

Meanwhile I have realized that this is a digikam settings problem and that I can indeed rely on the GXR's JPGs to judge exposures. This was my main concern. Now I can follow your advice and just use and enjoy the new camera !

Best,
Nicola

Hope maybe this is of some help. Mostly you should just use the camera and enjoy it and if you have the desire your will learn more over time. There is no right or wrong, it's only what you want to get from it.

• A.