Open Beep6581 opened 9 years ago
DrSlony, try to adjust the white level
Reported by michaelezra000
on 2014-02-28 21:58:57
To work around it, just change Highlight Reconstruction Method, but I didn't open the
issue to work around it. That is not desired behavior, and its especially no good when
you find out about it after saving the image because the thumb looks fine (panorama,
adjust one shot, paste profile to the rest, send to Queue).
Reported by entertheyoni
on 2014-02-28 22:25:09
Flat field is not applied to thumbnails - that is a separate issue:)
Reported by michaelezra000
on 2014-02-28 22:34:33
There is no need for it to, as long as it doesn't have bugs like this ;]
Reported by entertheyoni
on 2014-02-28 22:40:58
I'll try to figure out, which dcp-profile is applied to the FF-shot. Actually don't
know whether it's the same which is used for the RAW the FF gets applied to or a different
one.
But looking at the code, I detected another problem: Reference gray for FF is picked
by the four center pixels of the FF-shot. Picking from center with high blur radius
(as for vignetting correction) is a good choice, but it can be a problem, when a dust
spot is in center of the image and you want to use the FF for dust removal (small blur
radius)
Will investigate,
Ingo
Reported by heckflosse@i-weyrich.de
on 2014-02-28 23:02:04
But dust normally has no color:)
Reported by michaelezra000
on 2014-02-28 23:18:13
Hi Michael,
referring to point 1 of #5: If the calculation of the values for each channel of the
FF-File are different from the calculations of the raw file it gets applied to, that
could lead to colour shifts, I guess (only a guess)
referring to point 2 of #5: If there's a dust spot in center of the picture (where
the reference values are picked from) that could lead to correction in wrong direction,
I guess (also only a guess)
Ingo
Reported by heckflosse@i-weyrich.de
on 2014-02-28 23:29:35
Michael, to be more specific: After reading the code, I think it was made for vignetting
correction with flat field. For this case, it's a good choice to pick in the center
of the FF for reference brightness. But when it's used for dust removal and there's
a dust spot in center of the FF (dust spots can be big with large apertures, though
less pronounced) that might lead to wrong corrections.
Ingo
Reported by heckflosse@i-weyrich.de
on 2014-02-28 23:37:13
Hi Ingo, I suppose that FF performance would be best if FF is applied prior DCP. In
such case DCP needs to be applied once. However, there is a nuance. The DCP is normally
made from DNG file that is NOT FF-corrected.
For #2, I think dust would make a spot darker, and very unlikely would alter the color.
I recall the sampling from the optical center of the FF was made for vignetting correction.
If that is based on 4 pixels average, then this could be sampled from a larger area
to bypass the dust issue.
Reported by michaelezra000
on 2014-02-28 23:41:04
I was typing while you posted comment 8:)
Reported by michaelezra000
on 2014-02-28 23:42:06
How about this - if blur radius is <100, use average of 100x100?
Reported by michaelezra000
on 2014-02-28 23:43:27
Michael:
I don't think that dust in the center of the FF would alter the colour of the picture,
but it would make the picture darker, because it's the reference point for FF (have
a look at line 1278 to 1286 of rawimagesource.cc). And, what's important, I didn't
get this effect right now (only in my thoughts after having a look at the code), but
the effect should be there when there's a dust spot in these four pixels.
Concerning DCP: I think, your suggestion is a good base, but there's some need to discuss
this :-)
Ingo
Reported by heckflosse@i-weyrich.de
on 2014-03-01 00:03:21
See issue 2003
Flatfield requires variable white level to work with highlight reconstruction
Reported by torger@ludd.ltu.se
on 2014-03-02 11:52:09
I have seen this issue forever, but I just used other means for highlight recovery.
I always use FF by default, so I never found a cause.
D5100
Reported by raceviper13
on 2014-03-03 13:09:27
how do we get this addressed? do I send a flatfield, the settings and an image to go
with it?
Reported by raceviper13
on 2014-06-18 12:14:22
Yeah won't hurt to have more issues to test this on if someone picks it up.
Upload them to filebin.net and link us to them here.
Reported by entertheyoni
on 2014-06-24 12:12:51
I stumbled into this as I made the flat field correction for xtrans yesterday. I'll
have a look at it when I've test files for other sensors too.
Reported by heckflosse@i-weyrich.de
on 2014-06-24 13:01:35
http://filebin.net/ni3spoo14x
sorry for the delay.
Reported by raceviper13
on 2014-06-27 19:37:48
Currently, the clipped image photo's highlights turn purple only when "auto clip control" is enabled.
With @heckflosse giving an update to the clip control here #4891, it would be great if this issue could be tackled too. Because what's the point of automatic clip control if it gives you purple highlights? :wink:
Edited, here's an image and flat-field file for which you can clearly see the effect: https://filebin.net/q1za6mx6swhygx7v
@Thanatomanic As described in the clip control tooltip, the clip control prevents unclipped raw files from getting clipped by applying a flat field. In this case you should also not get purple highlights. If the raw file already has clipped highlights, clip control can't do much about that and can give purple highlights (which is also mentioned in the tooltip). In this case clip control should not be used.
Ah sorry, didn't read that. Would it be possible that clip control detects if there are highlights and then just automagically sets itself to 0? Or is this wishful thinking?
btw: left is without ff, right is with ff and auto clip control:
@Thanatomanic
Would it be possible that clip control detects if there are highlights and then just automagically sets itself to 0?
That should be possible.
Interesting, this is my observation:
Are you using the pp3 provided? I see that auto-ca correction is on, which shouldn't be the case. Otherwise, please apply Neutral and then only switch on the flat-field.
I confirm the issue when using neutral profile + ff auto clip control
I will try to find a solution for this issue when 5.5 is released. Though I can't promise anything...
Originally reported on Google Code with ID 2272
Reported by
entertheyoni
on 2014-02-28 19:35:07