Rawtherapee: Lensfun vignetting correction and clipped highlight

[falket]

Version: 5.3-9-g1fdc2d7
Branch: dev
Commit: 1fdc2d7
Commit date: 2017-10-09
Compiler: cc 5.4.0
Processor: x86_64
System: Linux
Bit depth: 64 bits
Gtkmm: V3.18.0
Lensfun: V0.3.2.0
Build type: release
Build flags:  -std=c++11 -march=native -Werror=unused-label -fopenmp -Werror=unknown-pragmas -Wall -Wno-unused-result -Wno-deprecated-declarations -O3 -DNDEBUG
Link flags:  -march=native
OpenMP support: ON
MMAP support: ON

I have tried to develop a raw image shot with my phone, for which i've just profiled vignetting (huge).

Without vignetting correction i'm able to recover almost all the details in the sky, but when i turn vignetting correction on, the sky becomes really clipped and unrecoverable.

I attach screenshot.

And here the dng, the pp3s (prova is without vignetting correction, the other one with vignetting correction on) and the lensfun additional xml for the phone (should be ok, but i'm not 100% sure) and the screenshot

https://we.tl/Fwic4YkbLu

Thank you in advance.

:

[heckflosse]

@agriggio Alberto, do we need an equivalent of the flat field clip control also for lensfun vignetting correction?

[agriggio]

@heckflosse might be a good idea :+1:

[heckflosse]

@agriggio @falket I will take the issue

I just tested using neutral profile and the lensfun entry provided by @falket

With current source the lensfun vignetting correction clearly clips. Left is without lensfun vignetting correction, right is with lensfun vignetting correction (black areas are clipped):

[TooWaBoo]

This happens for lcp profiles too.

[heckflosse]

@TooWaBoo If you can provide a raw and lcp to reproduce I will try to solve the issue also for lcp.

Ingo

[TooWaBoo]

@heckflosse It's an overexposed picture of my pocket cam.
https://filebin.net/u7hb0mjfrbpq9p3t

[heckflosse]

@TooWaBoo The current clip control (as implemented for flat fields) only works correctly for raw files which before vignetting correction are not clipped in highlights but are clipped in highlights after vignetting correction. Do you have such an example for lcp vignetting correction?

[TooWaBoo]

I've noticed this only for clipped highlights. Checked some other pictures but couldn't find one.

[Beep6581]

Status: we need a raw file with highlights near the clipping point so that when LCP vignetting correction is enabled, those highlights clip. We also need the LCP file.

[falket]

I think it could be "easier" with a full frame camera with a really fast lens. By they way, just a probably wrong idea, could be feasible to darken the center, instead of lighting up the corners?

[falket]

If someone suggest me an easy way to take a picture also for the lcp problem, i could ask some friend if he can or try myself to take one. Thank you.

[falket]

Finally i've been able to take a shoot with a lens with a lcp, that leads to clipped highlight when using the lcp from camera raw. @TooWaBoo @heckflosse @Beep6581

To summarize, you can find it here:

https://we.tl/7nxNcFOEyR

1) a PEF file together with the lcp file. Applying neutral profile and lcp leads to clipped highlight.

2) the "old" dng file for the honor 6a, together with the lensfun xml.

Thank you everyone.

[falket]

Reading a thread in the forum, i remembered this issue, tried with latest 5.7 dev and i have seen the bug is still here. I attach here the relevant files this time on google drive so they will not expire.

https://drive.google.com/open?id=1KccM6Pf_8duULWUOtLfXzTyYpc5JoFLy

Thank you.

@Beep6581

[heckflosse]

@falket Didn't try the dng, but for the pef you can simply disable clip-out-of-gamut colours and apply negative exposure correction until we get this automated. See attached screenshot (left neutral profile + .lcp, right neutral profile + .lcp + exposure correction of -0.25 and disabled clip...

Should work for the dng as well