Single Pixel slider is a GREAT tool, but it's broken and they don't seem to get it.
I've been lucky enough never to have had hot pixel problems, until last week. During a long sustained shoot at high iso (1600-6400) I started getting red, white and blue stuck pixels. How patriotic ;)
I discovered the Single Pixel slider under Noise Reduction and started sliding, however nothing seemed to be happening. Disappointed, I began using the Healing tool to patch the pixels and copy/paste settings to all affected photos. What a pita. I thought I must be doing something wrong with the Single Pixel slider so I did a search. I found an old post in the v7.x/8.x forums from five years ago that claimed a bug prevented the tool's adjustments from appearing in the Viewer unless the image was zoomed beyond "Fit", so I zoomed in to 50% and lo and behold the hot pixels disappeared.
Looks like the bug still exists, so I filed a request yesterday, and got a response today:
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"Jack (Capture One) Aug 31, 2020, 11:36 AM GMT+2 Hi Rob,
This is how the previews work. You see a lower resolution image as your preview that cannot render the hot pixels, due to the higher resolution required. You could try increasing your image preview size by going to Preferences > Image > Preview display size (cache) and adjusting accordingly. Then, regenerate the previews for the image by right-clicking in the preview or browser and selecting 'regenerate previews'. Kind regards, Jack Technical Support Lead, Capture One"
Hmmm, I don't think they get the problem. It's actually the exact opposite of what he explains should be happening. I see the pixels fine in the full screen preview. That's the problem. They should be gone. I wrote back trying to explain more and am waiting for a response. Does anyone else see this issue?
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Rob,
I think at 50% there is a chance, depending on the resolution of your sensor, etc,that the hot pixels may simply be binned as part of the pixel reduction requirement for reducing the size of the image.
I may be fortunate in so far as single pixel NR is not something I find myself using often but when I have used it it seemed to work as suggested.
That said there may be potential for specific occurrences of apparently stuck pixels to be misinterpreted as something else and therefore ignored by the algorithm. I could imagine that certain subject matter might be adversely affected by over zealous pixel binning for example. I have no idea whether that might be possible in the case of your images.
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New reply from support. Apparently this is a known years old bug and already reported. I'm not sure how it's supposed to work without being able to see that the hot pixels have been zapped. All other adjustments show on the preview. Strange:
Hi Rob,
Sorry if I wasn't clear enough. The preview will still show the hot pixels, but when you zoom in they will disappear, as you are viewing a higher resolution image which is capable of showing the fine adjustments to the pixels.
I'm aware that this is not optimal behaviour and have logged this as a bug previously. But it requires a lot of work to the preview and image rendering system in order for it to be fixed, hence why it's maybe been apparent for a few versions now.
I hope that we can address this in a future release/update.Kind regards,
Jack
Technical Support Lead, Capture One
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Very interesting. I have tried single noise reduction a few times before, didn’t see any changes and thought it just doesn’t work I thought maybe it has to do with the Fuji X-Trans sensor. It definitely would be good if there was a way to get rid of hot pixels during long exposures in a reliable manner.
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I know, I'm surprised they haven't changed this just to stop the complaints because I'm sure most people just assume it isn't working.
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Just took a closer look at some long exposures that had a lot of hot pixels. It seems that hot pixels are not limited to one pixel but often several next to each other. No matter how much I zoomed in or out I couldn't see Single Pixel Noise Reduction make a difference. It's also problematic that it can be used only on the background layer.
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I wonder what the slider does exactly
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First time dealing with hot pixels and had to dig up this thread to figure out what was going on. The slider itself works very well and removes the offending pixel, but preview does not display the fix unless you zoom in. But if you switch to proofing, poof, the pixel disappears. You’ll just have to ignore the offending pixel while you edit.
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Ben,
I think, as per an earlier post in the thread, the size of the initial Preview file may be a factor.
The preview file is generated early in the process - at the first point of C1 seeing the file and using whatever Preview size is set as the preference.
Typically this will mean the the preview is relatively low resolution compared to the source (RAW) file and so to retain the appearance of some detail the pixel binning and compression used are likely to retain bright spots as possible detail that is not to be lost when throwing away data. That situation may well persist so long as one is working at the original preview size.
Make the view bigger and the process reverts to the original file to source data with more information than the Preview has. At that point the process can display the correction. Starting with a bigger Preview will also offer more data to which to apply the very specific correction.
At least that is the theory.
Creating a bigger Preview file for future use would likely eliminate the initial problem - which has probably become more of an issue as Camera Sensor sizes have grown far more rapidly than screen resolution (for most people!)
The problem here is that once one knows this happens it's not really that much of a problem but until one sees how it works it does appear to be a very annoying problem.
Proofing is, in effect, another way to present on screen how the result are expected to look but with out actually changing the Preview file at all.
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It still doesn't work like it should.
And the last time I tried it, the 'fixed' pixels showed up in a reduced size JPG export. SO, useless.
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