Red & Green pinpoint spots

[Rick Dott]

Lightroom Version Number

Lightroom Classic Ver 9.2

Operating System

1. Windows 10

In the low light & especially night shots I'm editing I see random red and green pinpoint spots scattered around the picture. They seem to stay in the same position relative to the sensor when I move the camera. I know I have read about this somewhere but have been reading so much I that can't remember where or how to deal with in and if the pin points will transfer to a print? Any ideas? Rick

 

[Replytoken]

I would guess stuck/hot pixels. Most cameras allow you to map them out through the camera's menu system. If not, you can clone them out before exporting to print.

Good luck,

--Ken

 

[clee01l]

These are artifacts of low light photography. Some pixels fire “louder” than others trying to compensate . The result is a red or green burst at that pixel. Noise reduction will be able to handle it

 

[Rick Dott]

OK Thanks I'll look into a map and clone.
Would spot removal tool work too. I assume the map has to be applied before the photo is removed from the camera or can you make a preset for it?

 

[Conrad Chavez]

I assume the map has to be applied before the photo is removed from the camera or can you make a preset for it?

It depends on how you are doing it, because there are multiple approaches.

• If your camera has a setting with a name like Long Exposure Noise Reduction, try turning it on. It takes a noise sampling frame and applies it in camera. This can greatly reduce hot pixels in long exposures. But be aware that Long Exposure Noise Reduction might double the total shot time; if you take a 20-second exposure it might be at least 40 seconds until the camera is ready for the next shot.
• If your camera doesn’t have a setting like that, you can do it manually using a method called dark frame subtraction. You take your own noise sampling frame (for example, same exposure but with the lens cap on),then you manually subtract it from your images using layers in Photoshop. This is widely used in night photography so the steps are covered in many places online; I'm not experienced with it. I don’t think this can be done in Lightroom.

Also, if you’re having trouble getting rid of the spots with noise reduction in Lightroom Classic, try reducing the Detail value for Noise Reduction or Color Noise Reduction.

 

[Replytoken]

Cletus and Conrad's suggestions should also be applicable, but I initially suggested a hot pixel as you mentioned that it was in the same location in multiple shots. I think that you should probably do a combination of things that were recommended above. First, see if your camera will remap pixels. If it is a hot pixel, this should help. Then, see about using the long exposure noise reduction that Conrad referred to above. Yes, it will lengthen you exposure time, but the results can be reasonably good depending on camera, sensor, and exposure. If these don't work, or work well enough, then the spot removal tool should work if you do not have too many to address.

--Ken

 

[Paul_DS256]

Never heard of 'hot pixel'. Found this interesting article on DLSR sensor pixel issues Dead vs Stuck vs Hot Pixels

 

[clee01l]

If it is a hot pixel, this should help. Then, see about using the long exposure noise reduction that Conrad referred to above. Yes, it will lengthen you exposure time, but the results can be reasonably good depending on camera, sensor, and exposure. If these don't work, or work well enough, then the spot removal tool should work if you do not have too many to address.

--Ken

Hot pixels are “always on”. You should also see them in normal daylight.


Sent from my iPad using Tapatalk

 

[Replytoken]

Hot pixels are “always on”. You should also see them in normal daylight.


Sent from my iPad using Tapatalk

True. But given the wide subject matter that I shoot, it sometimes takes me a while to discover a hot pixel unless it happens to be in a very prominent location. I did not know if this was a similar case for the OP, so I initially recommended a round of pixel mapping to see if it would address any possible hot pixels as it is relatively easy to do and then test afterwards.

--Ken

 

[Conrad Chavez]

The article linked above mentioned something I have heard of before: Lightroom Classic does its own hot pixel remapping. That was also mentioned in the following thread on this forum:
https://www.lightroomqueen.com/community/threads/does-lr-do-something-to-hot-pixels.9658/
So in Lightroom Classic, if you still see hot pixels, those are the ones that Lightroom Classic hasn’t already mapped out. But it turns out a hot pixel is not just a pixel but a pattern that software recognizes, and the discussion below at the Lightroom Feedback site talks about why some hot pixel patterns are not detected, for example Lightroom Classic wants to avoid accidentally deleting actual image detail:
https://feedback.photoshop.com/photoshop_family/topics/lightroom-not-removing-all-hot-pixels
Those are the ones we need to take care of outside Lightroom, like in camera or in Photoshop.