Exporting a RW2 photo to JPG

Software darktable
1

I just noticed that exporting a RW2 to JPG in DT causes the output photo to be lighter than the original (1EV or maybe 2EV). I don’t know if I have to tackle parameters in export.

Using my Lumix in RAW+JPG mode produces exactly (at least for me) the same image in the two formats.

So, how can I get DT to export RW2 to JPG as identical as possible to the original? I see many options, export profile is set to “image settings” (the intuitive option)

Thanks

Darktable 4.6.1
Lumix FZ-10002

2

I also use a Lumix and RW2, there’s no problem.

Such issues are usually due to broken colour management on the computer.

Please provide details: operating system, what viewer is used, what display profile is set.

A test: import the exported JPG back into darktable. If it looks OK, it’s pretty certain that colour management (interpretation of the values in the exported file, and their conversion o the display) is the issue.

3

do you edit the image in darkroom before exporting? The default processing will differ since darktable isn’t aware of the in camera processing routines …

The camera embedds a jpg preview within the raw file - you never see the raw data :wink: so preview and separate jpg are base on the same operations in the camera.

4

Could you share a picture file for others to test. But as already said the RAW includes an embedded jpg which is not a true representation of what the raw looks like. Probably not important but OS might help and why use 4.6 when 4.8 stable release is available?

5

Are you processing the raw…When you first open your raw image it will be exactly like the jpg as it uses the jpg preview. When you move to darkroom view then the edit begins and the preview shifts to a version of the raw applying the default modules which can be highly customized but normally these will not give you an image that is ready without further work from the user and often trying to match the jpg will take a bit of work. If you like the jpg use the jpg and if you embark on a raw edit then start with a plan for composition, tone, color grading etc and then experiment and learn the tools to apply those adjustments…

6

I thought ‘the original’ meant what you saw in the darkroom. Is that the case, or are you comparing to the camera’s output? Does the exported file match what you see in the darkroom (for the raw file)?

7

thanks, … as far as I know, I never receive any warning from DT when a new version is available.
I have just installed 4.8.1 now

I am testing uploading images. jpg loads well, rw2 loads as a link…

8

You don’t really upload images in DT DT is non destructive so the import function simply notes the file location and creates a thumbnail. You can add copying your files from a camera or card or external drive with import and copy. Personally I do my own organization of my images before using the import feature which is basically equivalent to a file open feature…

9

If you mean uploading photos to this forum, then that’s how it should be: jpg will show as image, raw files as links for downloading.

10

Oh that makes more sense…I misunderstood with my reply…

11

thanks
OS : Windows 11 Home 23H2 build 22631.4037 installed 12-mar-2023

In DT lighttable I see the RW2 lighter and the exported-and-reimported-jpg darker
profile (in DT export options) is “image settings” (is this the display profile you are asking for?)

The attached two pictures have been downloaded from my camera (LUMIX FZ10002).

In Windows File Explorer, both (thumbnails) look the same. Double click on the jpg (Photos.exe, DT lighttable, Firefox, Gimp, Paint, …) display the same all the way
Double click on the rw2 (Photos.exe, DT lighttable, LUMINANCE-HDR) displays well only in DT, Photos.exe shows the photo ok during one second, then it gets darker (maybe -2EV or -3EV). LUMINANCE-HDR shows the photo with a kind of fog on top. Quite strage

Importing the jpg back into DT has no negative effect. The photo displays well in lighttable or darkroom. As well as exporting from DT

Double click on them (Photos.exe is launched) : jpg and rw2 pictures are shown as in File Explorer for a second, whereas the rw2, suddenly becomes darker (1EV or so)
Imported into DT, lighttable shows them equal.

SIURANA-cam
SIURANA-cam5472×3648 8.42 MB

SIURANA-cam.RW2 (22.5 MB)

12

Sorry, I don’t get it. First, you say the reimported JPG looks darker in the lighttable:

Then, you say it looks OK:

The export profile is not the display profile; the export profile defines how the colours are to be encoded in the output file (e.g. sRGB, Adobe RGB, and so on).
A display profile describes your monitor, it tells software how to ‘format’ (encode) the colours so they are displayed properly.
If different software use different display profiles, they send data to the display differently, resulting in visible differences.

13

thanks, I am not processing any file, I am just learning first steps, when I came accross the fact that RW2 images were darker outside than inside DT

My camera is set up to record RAW only (following the advice of a third person). Occasionally I record both in RAW and JPG, because digital zoom is only available for jpg

14

An unprocessed image will not look like your camera’s processed version. Raw images are not viewable at all without processing, so the camera embeds a processed JPG, which is also what it uses for previews. Darktable, by default, also uses that embedded JPG on the lighttable, until you open the raw in the darkroom. Many other programs also just show that JPG when ‘displaying a raw’.

15

yes, sorry, I am quite confused with all the topics involved in the workflow. The second answer (reimporting has no negative effect) has been tested step by step.

After all, I suppose I am encountering the “broken colour management” that causes this mess.

Maybe I musn’t look at photos in Windows, and only inside DT (or other editor) and the camera itself.

16

Be sure to export as sRGB (that is the default, and should work with all programs).

Then the remaining question is the display profile, that is, whether darktable uses the same as all the others.

Can you upload the xmp ‘sidecar’ that darktable placed next to your raw, and maybe also the exported JPG?

17

No problem. THere is a jpg preview embedded in your raw that can be extracted. The quailty of the preveiw does vary depending on the raw… I think Sony previews for some of their camera’s were small and some Nikon ones are quite good…but that is an aside but just to let you know if you only have the raw you can still get a jpg out of it and that is also what DT (and some other software) shows you in the initial preview until you begin an edit…then it shifts to the raw which will look often very different as it needs all that processing that is built into your camera when it spits out a jpg. Sometimes in software you will see the preview for a second and then it goes to the raw. In DT there are some default modules so if you go to the stack and click on original you will see roughly the raw with only the modules applied needed to make it an image…coming from your camera it looks like a grid of colored pixels to begin with.

Since of course they don’t share the recipe except for maybe with Adobe :smile: you need to now process that file to make the image that you imagine or would like to see…

Getting your system color management right is also important as @kofa mentioned… Stay away from the windows OS applications … for example on my Win11 system photos autoenhances my pictures and lightens them and it can’t be turned off…

I use xnview. It allows you to specify the icc profile for your display. If you do that and also for DT you can be sure that they both use the same display profile and you can take that out of the equation…

You can also confirm what it is set at in the OS but I like to be overly cautious and set it explicitly for each software that I use.

18

I think you are suffering from the expectation that darktable will process raw to look just like the jpg the camera is doing. That is not the design intent of darktable. See this section of the manual: darktable 4.9 user manual - process

You need to process the image, before you export it, otherwise you will end up with an image that is dull.

1 Like
19

Further to the link shared by @g-man

There is another raw editor called Rawtherapee. The explanation from that documentation perhaps has a bit more detail than the concise passage in the DT manual but the information holds the same… With DT your going to get a fairly neutral starting point not a jpg reproduction but this can be fully customized once you get the hang of it and then you will add some modules tweaked to your liking that will define your style and starting point… for sure use the jpg as a reference image but I would suggest that you don’t treat the raw with the notion of it being a “super” jpg and spend needless time trying to reproduce it because then you might just as well use the jpg…

See below taken from the Rawpedia documentation for the Editor portion of the software

https://rawpedia.rawtherapee.com/Editor#Eek.21_My_Raw_Photo_Looks_Different_than_the_Camera_JPEG

Eek! My Raw Photo Looks Different than the Camera JPEG

When opening a raw photo you may notice that it looks different from your camera’s JPEG, or from what other software show when viewing the same raw photo. In some cases this difference is minute, but in other cases it could be significant - the image could be darker, lack contrast, be less sharp and more noisy. What gives?

There are three things you must know first to understand what is happening here:

  1. Your camera does not show you the real raw data when you shoot raw photos. It processes the raw image in many ways before presenting you with the histogram and the preview on your camera’s display. Even if you set all the processing features which your camera’s firmware allows you to tweak to their neutral, “0” positions, what you see is still not an unprocessed image. Exactly what gets applied depends on the choices made by your camera’s engineers and company management, but usually this includes a custom tone curve, saturation boost, sharpening and noise reduction. Some cameras, particularly low-end ones and Micro Four-Thirds system, may also apply lens distortion correction to not only fix barrel and pincushion distortion but also to hide dark corners caused by severe vignetting or by the lens hood. Most cameras also underexpose every photo you take by anywhere from -0.3EV to -1.3EV or more, in order to gain headroom in the highlights. When your camera (or other raw editing software) processes the raw file it compensates for this by increasing exposure compensation by the same amount.
  2. When shooting a raw photo, most cameras embed within the raw file a full-resolution JPEG image with tone curves and other adjustments applied. Some raw files contain as many as three JPEG images differing only in resolution. Most cameras offer storing photos in one of three modes: “RAW”, “JPEG”, or “RAW+JPEG”. The embedded JPEG image discussed here is stored within the raw file even in just “RAW” mode! When you open raw files in other software, what you are usually seeing is not the raw data, but the embedded, processed JPEG image! Examples of software which are either incapable of or which in their default settings do not show you the real raw data: IrfanView, XnView, Gwenview, Geeqie, Eye of GNOME, F-Spot, Shotwell, gThumb, etc. It is worth mentioning at this point that if you shoot in “RAW+JPEG” mode then you could in fact be wasting space on your memory card and gaining nothing for it, as your raw files most likely already contain an embedded JPEG identical to the external one saved in “RAW+JPEG” mode.
  3. Most raw development programs (programs which do read the real raw data instead of just reading the embedded JPEG) apply some processing to it, such as a base tone curve, even at their most neutral settings, thereby making it impossible for users to see the real, untouched contents of their raw photos. Adobe Lightroom is an example. Comparing RawTherapee’s real neutral image to a pseudo-neutral one from these other programs will expose the differences.

RawTherapee, on the other hand, is capable of showing you the real raw image in the main preview, leaving the way you want this data processed up to you. When you use the “Neutral” processing profile you will see the demosaiced image with camera white balance in your working color space with no other modifications. You can even see the non-demosaiced image by setting the demosaicing method to “None”.

To provide you with a more aesthetically pleasing starting point, RawTherapee by default uses the Auto-Matched Curve processing profile, which automatically generates a tone curve to make the tones of the raw image match those of the embedded JPEG, if one exists. If one does not exist, you can use the Standard Film Curve processing profile, which applies a curve which looks good in most cases. Choose the sub-type (ISO Low/Medium/High) depending on how noisy your image is.

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Perhaps it is best to at least provide the link to the documentation than copy/pasting it all here without any credits or attribution…