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T
Txm
Participant
May 4, 2022
Question

Unknown noise in dark areas of image after rendering?

  • May 4, 2022
  • 3 replies
  • 886 views

So I've been having this issue for awhile now. I shoot A LOT of low light photos with a Sony a7R IV. After editing in lightroom and exporting I see this weird and annoying effect going on in the top left area and in the dark areas of my images. It almost looks like stars in space or a sparkle. Does anybody know what this is and HOW to correct it? I know the luminance slider works but i dont want to make my image look all plastic and weird with that. Thanks!

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3 replies

TheDigitalDog
TheDigitalDog
Inspiring
May 4, 2022

We really need a DNG which would bake all your edits and allow analysis of the raw exposure outside of Lightroom Classic. Can you upload such a DNG to something like Dropbox or similar? 

Author “Color Management for Photographers" & "Photoshop CC Color Management/pluralsight"
Conrad_C
Community Expert
Conrad_CCommunity Expert
Community Expert
May 4, 2022

Were the photos shot at a high ISO speed, or were they shot darker than the recommended exposure?

 

It looks like noise caused by boosting an underexposed image, and the same effect can be produced by shooting at a high ISO speed. The EXIF data for the photo shows that it was shot at ISO 2000, which is pretty high. On most good cameras, ISO speeds below 800 do not reveal that type of noise unless you over-boosted the shadows.

 

So the way to fix it is to keep your ISO speed as low as you can, while also exposing so that you don’t have to brighten it too much in software.

 

If you want to try and fix it in Lightroom Classic, it’s about more than just moving the Luminance slider. If you like a certain Luminance value, you can try to reduce the sparkles by also adjusting the Detail slider.

 

Also, noise and sharpening are related, so seeing white or colored noise sparkles can also mean Sharpening is too high, or Sharpening was used without Masking off the broad areas. It can also mean Texture is too high.

    TheDigitalDog
    TheDigitalDog
    Inspiring
    May 4, 2022

    It is possible that higher ISO produces less noise, so let's not go there until we can actually view the raw data in something like RawDigger.

     

    Author “Color Management for Photographers" & "Photoshop CC Color Management/pluralsight"
    T
    TxmAuthor
    Participant
    May 4, 2022

    Also another note, the effect is A LOT more noticeable on phones than on a monitor. But then lets say you were to download the photo, it would lessen itself. I'm really confused as to what this is.

    Conrad_C
    Community Expert
    Conrad_CCommunity Expert
    Community Expert
    May 4, 2022
    @Txm wrote:

    Also another note, the effect is A LOT more noticeable on phones than on a monitor. But then lets say you were to download the photo, it would lessen itself. I'm really confused as to what this is.

     

    This may be due to the different luminance or gamma settings between phones and computer displays. For example, if a display is calibrated for print, the luminance has to be relatively low (for example 90-120 nits). But many TV,  computer, and phone displays adjusted for casual/office use may be 150-250 nits, and much higher if set to full brightness. If someone likes a nice bright screen and hikes up the brightness, and they look at an image edited for a less bright medium, any problems in the shadows are going to become a lot easier to see.

     

    It’s just another reason to make sure you expose to minimize potential problems in the shadows. Of course, that is a challenge when shooting a low-light scene.

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