Rawtherapee seems by far sharper than darktable

Software darktable
#1

I developed the following raw image taken with my APS-C sony a6600 with both darktable and rawtherapee.
DSC00662.ARW (24.0 MB)
This is a detail of the image coming from DT

DT_DETAIL
DT_DETAIL1266×610 307 KB

DSC00662_03.ARW.xmp (9.7 KB)
And here the same detail from RT
RT_DETAIL
RT_DETAIL1265×614 287 KB

DSC00662.ARW.pp3 (11.5 KB)

What I find surprising is the difference in sharpness of the image between DT and RT; in a nutshell, RT seems by far sharper than DT.
Why is that and, in case, where am I wrong?
Is there any way to improve the sharpness of DT to make it comparable to that of RT?
Ciao
Vittorio

#2

In RT you have three kinds of sharpening activated: capture sharpening, unsharp mask, and edge sharpening. You also have wavelets enabled, which effects perceived sharpness.

In DT, you have the sharpen module and high pass.

So, this isn’t really good comparison as you’re not using the same modules.

1 Like
#3

@victor50 Welcome to the forum!

While what you say is true, I am guessing Victor wants to learn how to do sharpness well on dt.

(Could be a meeting topic @betazoid :wink:.)

4 Likes
next live meeting: March 28, 18:00 UTC
#4

…and the contrast equalizer.

Interesting topic!

2 Likes
#5

I’ve posted about the difference between darktable and RT many times.
It’s not just sharpening but amount of detail and the clean image.
I thought it might just have been because I use Fujis X-Trans sensor, and the RL deconvolution sharpening.
Over the years I have tried everything in dt from highpass, sharpen and contrast equaliser but nothing comes close.
Then along comes ART, in which I can achieve slightly better result then even RT using USM.
So, in summary, I always thought the difference was because dt did not have a deconvolution module but achieving the excellent results in ART using USM, I have to say I haven’t a clue why.
But the difference is there.

#6

@victor50

This is what I get by only using two instances of the contrast equalizer. Still seems far away from de result in RawTherapee, but I think it already somewhat closer than your darktable attempt. Maybe this is what you’re looking for?

image
image1212×583 316 KB

DSC00662.ARW.xmp (7.2 KB)

#7

DT with contrast equalizer and RL output sharpening through my lua script.
It seem plenty sharp to me, even too much

DSC00662
DSC006621129×620 412 KB

2 Likes
#8

In my experience you can easily achieve high perceived sharpness with dt but rt will reveal more fine detail.

2 Likes
#9

These are without any sharpening, Amaze demosaic only.

RT

DSC00662-1
DSC00662-1999×583 249 KB

DT

DSC00662_02
DSC00662_021129×620 340 KB

They look comparable to me, so it must be the capture sharpening in RT which is very good

#10

It might also have to do with parameter ranges and sensitivity. I find that I could easily exaggerate or destroy an image using max values in RT. As @Thanatomanic suggested, a way around the subdued nature of dt is to use more than one instance of a module; or use multiple modules to coordinate the enhancement, although iteration may sometimes introduce issues.

#11

The contrast equalizer module in DT has a preset ‘Sharpen’ but it the default setting is very heavy handed. I almost always have to turn it

DSC00662
DSC006621576×1177 622 KB
down.

#12

Yes, this could be a meeting topic indeed.

Concerning the topic: I use both programs and I think I have not noticed that one is sharper than the other, although the raws developed with RT seem to have more resolution. I think it has to do with the demosaicing. However, it is possible to sharpen photos very well in dt with two instances of the contrast equalizer.

1 Like
#13

Thanks a lot for the many answers.
Willing to stick to DT for many reasons, following your valuable suggestions I now develop my images according to these steps (as far as sharpness is concerned):

  1. demosaic with Amaze;
  2. exposure module;
  3. Color calibration;
  4. Filmic rgb;
  5. Sharpen module disabled;
  6. Local contrast;
  7. (More important!!) 2 instances of the Contrast equalizer module tweaking luma and edges fine details.

In so doing I get very similar results in terms of sharpness to Rawtherapee.
Of course, I’m not a “sharpness addicted” but landscape and generic architectural photos require this attitude.

#14

If you look closey to the discription of the “edge” tab you will see that it will only work if the luma or chrome curve has been set.
A separate instance of the contrast eq. with only the the edges curve activated won’t do anything. (unless I’m wrong)

#15

Actually I meant to say that I applied 2 instances of the contrast equalizer in which I tweaked both luma and edges in each of the 2 instances.

1 Like
#16

Oh that would explain why I had to crank up the curve to the maximum to get any appreciable effect. Weird.

#17

@MarcoNex, have you shared your lua script? it would be interesting to try.

#18

This level of sharpness is definitely hard to achieve in darktable (3.4.1). Here’s my attempt, mostly by being careful with the denoise and using a combination of contrast equalizer and sharpen. Still not sure it’s quite as good as RT manages but it’s not bad (still feels a bit overdone).

DSC00662
DSC006621237×615 503 KB
DSC00662.ARW.xmp (8.3 KB)

#19

Well my previous post shows that after demosaic only sharpness is comparable

#20

It’s in the repository, see contrib/RL_sharpen.lua.
It work on Windows and Linux, not tested on iOS.