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Noise reduction bug with Fuji GFX files.

Permanently deleted user
I just tried the noise reduction on files shot with the Fuji GFX 50s at ISO 1250 - and the results are very weird. There are artifacts visible (looks like tiny patches of moirée).

These artifacts are not present when I'm using noise reduction on files shot with a Canon 5D II at the same ISO or a PhaseOne P65+ at ISO 400.

https://i.imgur.com/00wh8o2.jpg

Is this a bug or does PhaseOne not want Fuji users to have the same improved noise reduction with their files? 🤓
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11 comments

Date Votes
  • SFA
    Just ISO1250?
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  • Permanently deleted user
    No, it happens at every ISO setting. I compared it to the previous version and the previous version (though noisier) does not produce these artifacts.
    If you look closely with the P65+ files you can actually see it happening too, although not as much.

    It seems that this "improved" noise reduction is not a prefect algorithm after all and it can only be used properly with lower frequency noise and not very detailed high frequency noise.

    I'd rather have the old legacy noise reduction mode. 😡
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  • SFA
    C-M-B wrote:
    No, it happens at every ISO setting. I compared it to the previous version and the previous version (though noisier) does not produce these artifacts.
    If you look closely with the P65+ files you can actually see it happening too, although not as much.

    It seems that this "improved" noise reduction is not a prefect algorithm after all and it can only be used properly with lower frequency noise and not very detailed high frequency noise.

    I'd rather have the old legacy noise reduction mode. 😡


    Are you viewing at 100%?
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  • Permanently deleted user
    Yeah 100%.

    So after tinkering for a bit I think I found the "problem":

    If you set the detail slider above 50-60% and the noise reduction above 65%, it'll cause these artifacts to show up with the GFX 50s files - and also with the P65+ files!
    The canon files are fine unless you set the sharpness to something ridiculous like 1000 Amount and 2.5 Radius. Then the artifacts also show up.

    Not sure why though. With the files from the Canon 5D MkII I can set the detail slider to 100 and it works perfectly fine even though the noise should be quite a bit higher on this one.


    I suspect the new engine only works well with a certain "type" of noise, if it's a very high frequency noise it gets confused.

    For now the best settings I've found are:

    Luminance: 40
    Detail:75
    Color: 5
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  • SFA
    I'm sure I have seen this reported before but can't recall when.

    However in beta testing I noticed a rather off effect with very fine details that involved vertical lines - which became rather jagged somewhat randomly. The effect was most obvious at 100 or 200%.

    I reported the problem and had a request to send a screen shot BUT, between reporting it and getting the request I had realised that something related to building the GPU kernel had not resulted in a good result so I forced a rebuild and the fine detail problem disappeared.

    Given that you are only seeing the problem with high resolution files or quite extreme settings it may be worth seeing what happens if you turn off Hardware Acceleration or force a rebuild of the GPU kernel build. (Assuming you have not already done so with a fully successful kernel build as the result.)


    Grant
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  • Permanently deleted user
    Well today I updated the GPU driver and I tested it with and without hardware acceleration - no difference, it's still there.
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  • Paul Steunebrink
    C-M-B wrote:
    Well today I updated the GPU driver and I tested it with and without hardware acceleration - no difference, it's still there.

    You are obviously using CO20. Can you confirm that you used Engine 20 on all examples as well? Or have you compared Engine 12 and 20 regarding the artifacts?
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  • Permanently deleted user
    Paul_Steunebrink wrote:
    C-M-B wrote:
    Well today I updated the GPU driver and I tested it with and without hardware acceleration - no difference, it's still there.

    You are obviously using CO20. Can you confirm that you used Engine 20 on all examples as well? Or have you compared Engine 12 and 20 regarding the artifacts?


    Engine 20 on all compared images. I made sure to double check!

    I also compared them to Engine 12 and while more details are lost at higher NR settings, those weird artifacts don't show.

    (DELETED - I did some more experiments and it does not seem like it only happens with newer cameras. The same artifacts also appear on older cameras at very high ISO settings. For example on a Canon 20D at ISO 3200 it happened too.
    It's just strange that this appears at a GFX 50s at ISO 1250 - which is not that high of an ISO for that camera.)


    I noticed that a higher noise reduction also results in a slight change in contrast, similar to a small increase in Clarity. I believe this is how C1 wants to counteract further degradation of details and that might make matters worse in some case.
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  • SFA
    C-M-B wrote:
    Paul_Steunebrink wrote:
    C-M-B wrote:
    Well today I updated the GPU driver and I tested it with and without hardware acceleration - no difference, it's still there.

    You are obviously using CO20. Can you confirm that you used Engine 20 on all examples as well? Or have you compared Engine 12 and 20 regarding the artifacts?


    Engine 20 on all compared images. I made sure to double check!

    I also compared them to Engine 12 and while more details are lost at higher NR settings, those weird artifacts don't show.

    (DELETED - I did some more experiments and it does not seem like it only happens with newer cameras. The same artifacts also appear on older cameras at very high ISO settings. For example on a Canon 20D at ISO 3200 it happened too.
    It's just strange that this appears at a GFX 50s at ISO 1250 - which is not that high of an ISO for that camera.)


    I noticed that a higher noise reduction also results in a slight change in contrast, similar to a small increase in Clarity. I believe this is how C1 wants to counteract further degradation of details and that might make matters worse in some case.


    FWIW I can see something similar in some Sony files so I think you are correct that is it not necessarily camera dependent.

    However if I apply only NR adjustments to the images, which according to the histograms are perhaps a touch under exposed, I don't really see any problems.

    On the other hand if I apply NR after some fairly extensive Exposure, HDR, Levels, Clarity and Curve adjustments, the marginal "details" that seem to be available for retention (but probably should not be considered as details) can become a problem.

    Having revisited the editing experiments for the files I have and started with NR and a minor additional adjustment compared to the default values - just to take things a little further - followed by somewhat reduced (or even removed) adjustments for the other tools the problem has, effectively, disappeared.

    In these particular files I think there is an element of some "details" in the captured image not being "real" details but a factor of the lighting available and that probably does not help when pushing some of the adjustments across what would be perceived by the viewer as likely to be relatively large, consistent areas of a quite dark colour. To the eye the problem only appears at 100% on screen and at an abnormal viewing distance for the scale of the image.

    So it appear with these images it can be avoided most easily by approaching the edits in a different order in V20. Basically make the desired NR reductions early in the process and add the rest afterwards. Or simply live with something very close to the default NR which, for printed output, may be enough. (I have not checked that but think it likely viewed at a sensible distance for the print size.)

    Grant
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  • Permanently deleted user
    I think you're right though it's a bit annoying that we have to find these things out ourselves and there's no "manual" to explain this behavior.

    I would also add that noise reduction is only really important when looking at a file at a large magnification. At a low(er) magnification (eg. printe at 8x10" or so) noise reduction is not necessary at all.

    Also it's probably best to only really use it to slightly reduce noise (at the name of the tool implies) and not to eliminate noise altogether.

    It's just a bit weird and kind of sad that it works better with an old and (rather) low res camera like the Canon 5D II and not as good with a newer Sony sensor (which my GFX also has).
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  • SFA
    C-M-B wrote:

    It's just a bit weird and kind of sad that it works better with an old and (rather) low res camera like the Canon 5D II and not as good with a newer Sony sensor (which my GFX also has).



    Works differently I think, based on much less data from the older camera?

    The newest tech for high resolution sensors and some great lenses to go with them has introduced some big challenges as well as technically remarkable results.

    Back in time creating a relatively soft focus portrait was "normal" and could be gently enhanced in camera by an experienced practitioner as required.

    These days the expectations for sharpness are such that the sharpest parts of an image are incredibly sharp, what would once have been considered adequately sharp is not thought of as out of focus and anything not in the immediate plane of focus or just outside it looks very soft indeed.

    Fixing things in software is not always simple - although perhaps easier than any type of post processing in a fume room.


    Grant
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