[Digikam-users] Re: Processing RAW images to get to the look of the jpg preview

[Martin (KDE)]

Am Donnerstag, 23. Juni 2011 schrieb Sven Burmeister:
> 
> > I don't think your problem is gamma only. The gamma curve only
> > depends on the colour model you use to view the picture (sRBG,
> > Adobe RBG, Apple RGB ...). It should almost never be necessary
> > to adjust this by hand. But I have no clue what the problem of
> > digikam is here.
> 
> You can try this. In digikam, open a RAW image that has visible
> highlights with the demosaicing tool and set highlights to
> "rebuild" or "blend". You will get a very dark image and thus need
> gamma. In darktable you get the same results regarding highlights
> (or better) but without a dark image or having to apply gamma and
> I would like to understand why because it would make RAW
> demosaicing in digikam easier if it worked as it does in
> darktable, regarding colours and highlights.

I try digikam for raw development every now and then. But for me it is 
to limited. That's the reason for using ufraw and darktable in the 
last three years.

> 
> > Darktable uses a good sets of defaults and by default the base
> > curve is not linear. this may be one main difference.
> 
> Yes, it's that base curve. Is this the equivalent of the curve in
> digikam's demosaicing tool? Did you ever use any curves in
> digikam? When I tried handling the points on the curve, i.e.
> placing them by dragging, seemed very hard to me and I often get
> lines curves that have sharp bends whereas the "sliders" in
> darktable's curve-tool seem to work better for me. If I'm not the
> only one, I would file a request to enhance the usage of digikam's
> curves.

Curves are a complicated matter. Using a curve in digikam with a 
similar shape as the base curve in darktable will most likely lead to 
different results. One curve works on linear data and others after 
colour space is applied.

> 
> And I noticed that darktable has presets for different kind of
> cameras for that curve. Having that in digikam would also be
> helpful I think.

But I don't think that this will ever happen. To get digikams raw part 
to a similar state as darktable already has is to much of work and 
will confuse to many users. And the Unix philosophy is against this. 
Use one tool for one problem but use the best. And to my point of view 
for raw development this is darktable.

What I hope for is a better "integration" of darktable and digikam. 
Both use (or will use) xmp sidecar files and it would be great if they 
can use the same file and share basic settings where the special 
settings of the other program will not be destroyed.

> 
> > Ah, there is a noise reduction plugin. There are at least three
> > ways to reduce the noise.
> > - Raw denoise
> > - Equalizer (a preset for denoise is available)
> > - denoise (very slow) (may be available in git only)
> > 
> > Equalizer is the most complex one thou. Here you can play with
> > luma and chroma noise independently.
> 
> I'll try that out. Equaliser did not sound like anything
> noise-related to me. 

I first ignored the equalizer as well but it is a great tool. try it 
out. There are presets for denoise alone and combined with sharpen.

> RAW denoise is marked as obsolete which is
> why I did not try it. The third option is not present in my 0.8
> package.

That's the reason I suggested the git version (or, if you use ubuntu, 
take Pascal's packages). The git version is way ahead. Darktable made 
amazing progress. I tried revision 0.5 about one year ago and to me it 
was not usable. With revision 0.7 (about November 2010) I completely 
switched to darktable for raw processing. and raw denoise may be 
available in git version only as well.

> 
> Sven

Martin