Hot Pixel Removal Issues

Stephen Zwerling

• August 11, 2023 15:05

Using a Lumix S5, I have taken photos of the night sky with long exposures  (15 sec) and high ISO (3200). I expected some hot pixels; I got many, mostly red in colour. I attempted to remove these with the noise reduction single pixel slider, however regardless of the value of the slider i set, the hot pixels remained.

However, when I used the viewing area slider to zoom in on the image, the hot pixels disappeared, even if the single pixel slider was set to a zero value. I needed to zoom in to at lease 70% for the hot pixels to disappear. Can anyone explain this phenomenon? (This is on a MacBook Pro 16 inch screen.)

The support text about noise reduction states that the single pixel slider is designed to remove white hot pixels. Is there any way to remove red hot pixels in Capture One other than but cloning or healing individual pixels?

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  Stephen Zwerling

  • August 11, 2023 15:25

  Well, Martin, it might not just be you, but you and me, at least among those that admit to it. 

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  BeO

  • August 11, 2023 16:00
  • Edited

  

  Can anyone explain this phenomenon?

  There is an observation by others and me some time ago that the noise reduction tool only works in high zoom levels and is disengaged on lower zoom levels. Assumption is that this is for performance reasons.This can lead to what you've observed, as well as to magenta color cast for high-noise images.

  Distracting for viewing and image editing but in the end the export should not show any issues.

  DXO for example only engages sharpening the image preview in 70% or higher zoom levels or so (at least what I've observed), that is even worse.

  I believe I made a feature request years ago, not sure though, to set the zoom level optionally in the preferences, but I think there is little chance...

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  Stephen Zwerling

  • August 11, 2023 16:19

  Thanks, BeO. I'll try exporting.

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  Stephen Zwerling

  • August 11, 2023 16:32

  Exported 2 variants: one with zero single pixel value and one with a single pixel value of 10.

  The variant at zero showed the hot pixels still present upon zooming in on the jpeg, but the variant exported with a single pixel noise reduction setting of 10 did not show any hot pixels.

  The value of 10 was an automatic selected value by Capture One.

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  BeO

  • August 11, 2023 16:52

  

  So, no Lumix mystery :-)

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  Per Borjesson

  • August 11, 2023 19:14

  I found this helpful:

  https://support.captureone.com/hc/en-us/community/posts/12229095707549-Dead-pixels-are-visible-from-zoom-out-

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