On 17/02/2015 19:24, Marc Cousin wrote:
> On 17/02/2015 18:39, Francisco Cribari wrote:
>> Dear Marc:
>>
>> [1] May I ask you which base curve you used? I noticed you did not use
>> the Fuji X100S base curve that comes with Darktable.
> That's because your image is DR-200. I usually change the basecurve a
> bit and raise the exposition +1 to compensate, automatically (I have a
> lua script to do that). This basecurve boosts a bit the low lights. I'm
> not sure it is better, it's just the way I like it, and I tried to make
> it look close to what the camera produces with DR-200.
>
> Maybe I should calibrate the camera in DR-200 to get a correct
> basecurve, one of these days, instead of relying on my handmade
> basecurve :)
>
>>
>> [2] I noticed you used an agressive denoise profiled setting (wavelet +
>> color): strength = 3.819.
> Yes, I still had a bit of moiré without such an agressive setting on
> your image. But maybe I went a bit too far, I don't know. I did it very
> quickly (I think my result was a bit overexposed, I just removed the
> moiré and got rid of the green artefacts I got by applying defringe).
> The purpose was just to show you that the way to go was probably the
> color/wavelet denoising (the only one I'm applying, most of the time).
>
>>
>> [3] This may be off-topic, but what are the advantages of an X-Trans
>> sensor for those who shot RAW? All my other gear have Bayer sensors
>> (Nikon D800, Nikon D7100, Nikon D7000, Canon G1X etc.) and I have never
>> had that much problem with moiré (the Nikon D7100 camera does not have
>> an AA filter). I have a couple of friends who have Nikon D800E cameras
>> (no AA filter) and they have not encountered problems with moiré either.
>> On the other hand, I have been delaing with moiré in several X-Trans RAW
>> images in DT. The default demosaic method is now different for X-Trans
>> images in DT which signals that moiré is a concern when it comes to such
>> images. Are there clear X-Trans advantages to X-Trans sensors that make
>> they worth? Are the X-Trans demosaic algorithms mature by now or can we
>> expect improvements in the next few years?
>
> On this point, I cannot really comment. I chose my camera (XE2) mostly
> because of the way it works (dials) and because of the XF lenses (good
> quality, aperture ring), and I got very good results straight from the
> camera when I tested it.
>
> That is my first and oly digital camera. I used to do film before, so I
> cannot even compare with Bayer sensors.
>
> Are you or your friends also using darktable with their cameras ? Or are
> they using Lightroom or another tool that may already do the denoising
> by default ? Or maybe, if they use darktable, they already do denoising
> by default ? I guess darktable needs a bit more tweaking than most
> proprietary software (in fact, I don't know, I never used any other tool
> except rawtherapee).

I'm still wondering about a problem I've seen very clearly with this 
RAW: when denoising with wavelets, there are green artefacts on many edges.

Here is the original image. Only demosaic (markesteijn 3 pass, with five 
times color smoothing), basecurve

https://drive.google.com/file/d/0B_liIOwDeWUmWnVSMVdpcFp2bU0/view?usp=sharing

There is moiré, and small artefacts on the camera's edges, but it's not 
that bad.

Add a profiled denoising, wavelet, on color. Be a bit more agressive 
than the default values.

https://drive.google.com/file/d/0B_liIOwDeWUmeTZLUnk1eDBubHc/view?usp=sharing

Moiré is gone from the shirt. But you get green on lots of places… on 
the camera for example.


Adding a very aggressive defringe is a way to get rid of this green, but 
destroys a lot of colour...

https://drive.google.com/file/d/0B_liIOwDeWUmXzRBZG53bHdYaFE/view?usp=sharing

But I feel that the defringe shouldn't be needed here (or at least not 
for that), and there is something I don't get about the denoising…

Could someone shed some light on this ? :)

The original RAW file was here: 
https://dl.dropboxusercontent.com/u/2171814/_FFX7922.RAF

Regards

Marc

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