Noise

[Manfred M]

What does the histogram look like when you first open the file in Lightroom?

Peter - I'm not sure what looking at the histogram does?

The histogram is nothing more than a distribution of values in the image. There are significant dark areas, especially around the quarter tones, some mid-tones and some highlights. There would be little to no data on the noise component as it would be buried in the values in the histogram.

There is noise visible in the sky, which is exactly where I would expect to see it.

[DanK]

I was curious about the histogram too—to see whether there was room to expose more, to lessen noise. There isn’t. I think the best option might have been to bracket.


Sent from my iPhone using Tapatalk

[TonyW]

I have often noticed something like noise in a clear blue sky but when I look closely there seems to be some regularity to it. This suggests to me that it might be something else. For example, could it be incomplete de-mosaicing? I haven't looked closely but I think it is not necessarily at high ISO. Perhaps over sharpening, especially deconvolution sharpening, could cause it.

[Rufus]

Bill - Thank you for the additional information in #20.

[Manfred M]

I have often noticed something like noise in a clear blue sky but when I look closely there seems to be some regularity to it. This suggests to me that it might be something else.

It is likely the effect of outdoor lighting reflecting off of water particles in the surrounding air. I see this effect in a lot of my night shots, especially those taken in the warmer months or shots taken near bodies of water in sub-zero temperatures. They add a mottled look to the sky. Rather than working with noise reduction tools, I find doing a selection of the sky and applying a Gaussian blur to it and then locally darkening the sky is usually an easy cure for this issue. The only time this method becomes problematic is if the sky is clear enough to have a few stars visible in the night sky.

[Rufus]

As coincidence would have it, a picture almost identical to mine appeared in the local newpaper today. I think mine was better despite the noise

[Rufus]

It is likely the effect of outdoor lighting reflecting off of water particles in the surrounding air. I see this effect in a lot of my night shots, especially those taken in the warmer months or shots taken near bodies of water in sub-zero temperatures. They add a mottled look to the sky.

The Guildhall is not very far from the sea and it had been raining not long before the shot was taken. Southampton and its neighbouring areas seldom see snow or experience sub-zero temperatures due the the Gulf Stream and protection offered by the Isle of Wight which sits at the bottom of the Solent. But yes, there could well have been water particles in the air.

Rather than working with noise reduction tools, I find doing a selection of the sky and applying a Gaussian blur to it and then locally darkening the sky is usually an easy cure for this issue. The only time this method becomes problematic is if the sky is clear enough to have a few stars visible in the night sky.

Thank you, Mandred, for another great tip for me to remember. and one that is well within my skill set