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C1 noise reduction "creating" hot pixels ?



  • BeO
    Top Commenter

    C1 does not have a per image or per variant history which can be undone as in other software. The global Undo function undoes every action, including switching images, and this is a good thing as you can undo changes on previous images too, and you usually want to see this effect, hence swichting it necessary. Has always been like this.

    You're welcome, at least two of the guys here in the thread volunteer...

  • philip brosens

    I expressed myself badly - sorry for the confusion.

    Those crosses sometimes - but not all the time - appear both in the thumbnails and the preview.  But in the preview they last only for a very short time and most of them disappear quickly.

    I meant the button to undo your last adjustment in an image - sometimes it makes me jump to another photo.  I'll have to study that one ... 

  • philip brosens

    The odd thing with the artefacts is that C1  seems to behave differently every time I open the program and so it's difficult to pinpoint what's wrong.

  • BeO
    Top Commenter

    Ctrlz+Z  / Undo button beloe is what I meant,


  • philip brosens

    Yes that one. The Undo/Redo button.

    As far as I can remember when there were no adjustments you could undo it was just greyed out.  Now, it doesn't grey out and makes me go back and forth between photos.

    I never noticed that before ;-)

    By the way, today C1 is behaving itself really well.  NO red or blue crosses, dots or blocks anywhere.



  • SFA


    I don't know whether this will provide any useful guidance but the variability you are seeing in the visible presentation seems to suggest that whatever is happening is happening in the processing being applied for on-screen display but does not appear in the final output.

    What C1 does for display purposes when EDITING is to use a base Preview file as a surrogate for the RAW (to save memory and speed up performance) and then apply the edit instructions on top of that base. The preview size suggested as optimal is screen size dependent so that the Preview file, with some zoom-in capability, is likely to be usable most of the time.

    However, if one zooms in a significant amount C1 may elect to  recalculate for the whole image from the source file in order to make full use of the detail available at that zoom level.

    (The same would be true in the opposite direction if one started with a large Preview file and applied an output recipe and Proofing that would deliver a much smaller, compressed end result.)

    So what you are seeing, or so it would appear, is that result of display processing applied to the preview but, presumably, based on the discovery of possible hot pixels found on the sensor for that particular shot according to data in the source file.

    I wonder if there might be some confusion in the processing between the cameras internally identified and mapped information about hot pixels and, perhaps, some internal C1 assessment based on the settings in use for NR (for example).

    That said, given your last sentence above, has anything changed on your system since yesterday? GPU driver update overnight or anything like that?

    One other thought is that possibly some glitch in a process somewhere was leaving some temporary data lying around in the depths of the processing memory that might be discovered and used erroneously by a later process.

    A shutdown and reboot offers the OS a chance to tidy up any orphaned files  - mainly to recover disk space but in some circumstances I have observed the process solving previously persistent issues like crashes and niggling glitches of other types.

    The randomness you have observed would fit into that sort of "irrational pattern" of results. Since we have not seen the Forum filled with a rush of similar reports of problems with that camera model we might consider that there is something possibly unique about the results you are seeing. 

    It's not impossible that no one else using C1 also shoots a lot of dark subjects at high ISO but I rather doubt that. So, especially given the randomness observed, the possibility of some sort of unusual local condition within your setup might be contributing to the problem. 

    If C1 continues to behave itself a local glitch of some sort might well have been proven to be the case. If the problems return I think you would need to involve the C1 Support Team in the analysis work.

    It would be interesting if you could work with your problem images on another computer to see if the problems appear there as well. Alternatively, if you are willing and able to share one or two of them for others to test, we could discover whether the same results are observed when using other systems.

  • philip brosens

    I have C1 on all three my computers.  My Macbook is old, but still working well.  I have a Surface Pro with WIN11 installed and I have a desktop still running on WIN10.

    All 3 had this problem, but on all 3 three the artefacts would behave differently.  The Surface Pro with WIN11 seemed to be worst off.

    The screenshot of the photos are very dark, but I brought exposure down on purpose so the artefacts would be clearly visible.    Bringing down the exposure completely has no influence on the brightness of the artefacts.  I guess that if they were hot or stuck pixels the image would be darkened, including those pixels.

    I've now openend C1 on my desktop with WIN10 (it's a recent desktop and more than powerful enough for C1) - and just like earlier today on my Macbook all is working well - with no artefacts in the previews or thumbnails.

    I also sent a screenshot to Fuji to hear what they think, but it'll take some time for them to reply.  I was thinking that maybe some bug in the firmware of the camera could be the cause of the problem.

    I'm no expert on stuck or hot pixels, but I've had them before with my Nikon D850. They appeared  from a certain ISO all the time and always in the same place - they wouldn't jump around or disappear and reappear when regenerating previews and they would also appear in the exported jpegs.  Here, fortunately, the exported image is clean.

    I've just tried again on Mac.  All seemed clean, but regenerating the previews of some of the images and they reappeared ... again in other positions than the ones before.

    So, immediately I undertook the same action on the WIN desktop and there all is ok.

  • philip brosens

    I realised I hadn't deleted C1 21 so I imported the images in version 21.  I didn't know if my camera was supported by 21, but it is and no problems there.

    I'm a bit embarrassed - I should have thought of it before.

  • BeO
    Top Commenter

    If the problems don't come back for a while this might be a helpful hint to add your bug ticket. Now you can start have fun with the new camera :-)

  • philip brosens

    Thank you all for your suggestions, help and patience !

  • Claudia Haarfee

    Just forget it.

    There are some pixels shown, when the image is zoomed to fit in the window. They magically disappear while increasing the zoom level. These errors are also exported (!!)

    There is a 4k video of that: 

    I have the problem since more than two years ago (first occoured in version, reported in September 13, 2020, now in, reported in December 25, 2021, it is still here).

    Best solution from the so called support:
    "Unfortunately, we cannot comment when this issue will be fixed, but rest assured that it has been reported and will be looked into.

    We also cannot guarantee that this will be in the next service release, but we will do our best to roll out a fix as soon as possible."

    I suggest, they give a shit on this error.
    My requests were marked as solved without any useful comment at all.

    From a technical community I got the tip, that zooming the image in the export dialog to 200% will help. Well, it reduces the false pixels unfortunately not every time. The result is better, but the workaround wont prevent it at all.

    "Buy an Upgrade" was also a genius idea. My last version will be C1 V23, if there are still pixel errors, I will change back to lightroom and demand my money back.


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