@heckflosse in my case, using version g8bb06c2_20210121 I tested all the demosaic methods and they all gave the issue 
Disabling highlight reconstruction fixes it here.
Can confirm disabling highlights reconstruction does fix it. Yet version 5.8-2735-g8bb06c2_20210121 had no issue even with highlights reconstruction.
That would actually explain it, since you don’t even need to turn reconstruction off, you just have to switch it to Blend for the black blotches to go away.
I can confirm all @heckflosse’s comments and more:
Using the latest development version:
- It only shows when using amaze+bilinear,
- Turning off highlight reconstruction fixes it (only colour propagation shows this),
- Turning off chromatic aberration-> auto-correction fixes it,
- Turning off capture sharpening fixes it.
Also tried all the other modules that are turned on in @stefan.chirila’s pp3. None of those show any effect.
I can reproduce this even more generally:
- Start from Neutral
- Choose any demosaicer you like
- Push the White Point up to 5 or something high (this aggravates the effect)
- Set Highlight reconstruction to Color propagation
Boom, artifacts.
I have traced it to this commit by @jdc backporting something from ART, so @agriggio might also want to have a look for himself Improve HLreconstruction color propagation - best transitions - code … · Beep6581/RawTherapee@b554f52 · GitHub
What I don’t understand is why a core method was casually changed without mention anywhere.
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That I also don’t understand. Even more, by that change it got a serious slowdown…
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Sorry, its my fault.
Probably the best solution is to disabled this improvment
Promised, i won’t do it again
Sorry again
Jacques
Well, let’s Alberto have a look first. If things are not problematic in ART, then we might as well revert. But if things can be fixed, there may be a very nice improvement to the reconstruction.
This change followed a discussion on Darktable in january, and Alberto @agriggio made proposals to improve HR. They have been tested by ART users, and by myself. The improvement is significant.
But, it leads to a slowdown and in some cases to bad behaviour.
Considering the positive opinions, I didn’t go through the “issue” stage of RT, it’s a mistake? but who doesn’t make mistakes?
Sorry again
Jacques
I tried reproducing in ART but I couldn’t, fwiw
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I’ve also seen this. I use RCD/vng demosaic. It appears in the highlights with colour propagation.
@agriggio I can reproduce it in (edit: current dev build of) ART, can you try with this arp? S7_09850.ARW.arp (10.8 KB)
Confirmed, thanks! Here’s a fix (the patch is for ART, might need to be adapted for RT):
diff --git a/rtengine/hilite_recon.cc b/rtengine/hilite_recon.cc
--- a/rtengine/hilite_recon.cc
+++ b/rtengine/hilite_recon.cc
@@ -951,7 +951,7 @@
#endif
for (int y = 0; y < H2; ++y) {
for (int x = 0; x < W2; ++x) {
- guide[y][x] = Color::igamma_srgb(Color::rgbLuminance(rbuf[y][x], gbuf[y][x], bbuf[y][x], imatrices.xyz_cam));
+ guide[y][x] = CLIP(Color::igamma_srgb(Color::rgbLuminance(rbuf[y][x], gbuf[y][x], bbuf[y][x], imatrices.xyz_cam)));
}
}
}
I tried with the patch Alberto @agriggio. there are always artifacts
But, If I replace CLIP by clipL
with
constexpr float clipL(float x)
{
return rtengine::LIM(x, 100.f, 65535.f);
}
Only is changed the low limit… 100.f, instead of 0.f
No artefacts (at least on this image)
But it not fixed IMG_3346.DNG
Jacques
Then, If now we change Guidedfilter parameter…artefacts are gone on IMG_3346.DNG
// guidedFilter(guide, mask, mask, 2, 0.001f, true, 1);
guidedFilter(guide, mask, mask, 3, 0.1f, true, 1);
jacques