Halo Help Please

[billtils]

This is SOOC, shot in Skye at the beginning of January this year. The weather was pretty much what would be expected at that time, but not expected was the halo at the mountain - sky interface. I don't shoot a lot of landscapes and this is one of very few taken in these weather/lighting conditions.

Any advice on what caused the halo would be very much appreciated. Please note that the halo issue is the sole reason for posting - there has been no post work of any kind, and I do know that it can be cloned out, I'd just prefer not to have it there in the first place .

Thanks.

[Manfred M]

Looks like an artifact from sharpening at first glance. I've had the same thing happen in images of hills / mountains against the sky. There is such a difference in luminosity where the mountain and sky meet that this gets exaggerated.

You say that there is no PP, but that is not strictly correct as both the raw processor or the camera's jpeg conversion do some sharpening. If this is from a raw image, the default sharpening settings of the raw convertor could be the cause. The downsampling and jpeg conversion can do this as well.

[billtils]

... There is such a difference in luminosity where the mountain and sky meet that this gets exaggerated.
You say that there is no PP, but that is not strictly correct as both the raw processor

Thanks Manfred

Yes, I did wonder if it was related to the considerable luminosity difference. And yes, I understand what you say about there being in-camera and raw processing, but these are default settings that would apply to all my images, and this set is the only one where there has been this noticeable halo before any other processing.

Looks very much as if your luminosity suggestion could be the answer.

[DanK]

I agree. It looks like oversharpening to me, and edges with very large differences in luminosity are precisely where this would be most apparent. Looking elsewhere in the image, it seems quite highly sharpened.

I don't shoot Nikon, so I have no idea what the various JPEG picture styles are. However, there is no reason to believe a priori that "default" implies "little sharpening." The default is presumably what Nikon engineers thought users would most often want in the majority of their images. You may be able to find this out. In the case of Canon, some information about the processing settings of all the JPEG picture styles is available online.

[billtils]

Thanks Dan

The raw conversion recipe I use in Capture One does not include sharpening. I'm going to try and replicate the effect if I can find a suitable combination of weather and scene and develop the card in Capture One and in DxO to see if the halo is consistent.

Unfortunately I can't do that right now, nor can I check the in-camera sharpening setting as my D750 is in the serial number range for recall for shutter replacement. It hasn't shown any signs of the posted problem but on the basis of better too soon than too late I sent it in. It was two months before they sent me the mailing label and they've now had the body for 3 weeks ... Oh well, maybe they've lost it and will offer me a D850 in recompense .

[billtils]

Unfortunately I can't do that right now, nor can I check the in-camera sharpening setting as my D750 is in the serial number range for recall for shutter replacement. It hasn't shown any signs of the posted problem but on the basis of better too soon than too late I sent it in. It was two months before they sent me the mailing label and they've now had the body for 3 weeks ... Oh well, maybe they've lost it and will offer me a D850 in recompense .

Looks like I should post moans to CIC more often - I just checked and the repair status has been updated to "In progress". The downside is no D850 ...

[Manfred M]

Looks like I should post moans to CIC more often - I just checked and the repair status has been updated to "In progress". The downside is no D850 ...

Nikon's automated system reported my camera was "In progress" and they did not discover that they had lost it until I telephoned several times and they physically had to look for it. I don't know what turn around time they have on the warranty work, but for regular repairs, Nikon Canada is quoting 7 - 10 working days.

[billtils]

Nikon Canada is quoting 7 - 10 working days.

Manfred, the local (and very good) authorised Nikon repair shop tell me it's about 2 weeks. I'll check the status again tomorrow and if it's still "In progress" will try to give them a call.

[billtils]

Just heard it's on its way back home

[billtils]

It's back safe and sound. The inbuilt sharpening was at +3, which appears to be the default setting. I'll see what difference changing it makes to high contrast shots - if it stops raining and I can find a suitable subject

[xpatUSA]

It's back safe and sound. The inbuilt sharpening was at +3, which appears to be the default setting. I'll see what difference changing it makes to high contrast shots - if it stops raining and I can find a suitable subject

After the fact, but ImageJ thinks they were halos too . .



Horrible, (to a pedantic eye) . .

Just to make you feel better, my proprietary converter applies enough default sharpening to raw images that halos are also clearly visible in a sharp shot with high-contrast edges. I turn my slider down to between -0.5 and -1.0, depending on the shot and the particular camera model used. I prefer to do my "capture sharpening" later.

[billtils]

After the fact, but ImageJ thinks they were halos too . .

Horrible, (to a pedantic eye) . .

Just to make you feel better, my proprietary converter applies enough default sharpening to raw images that halos are also clearly visible in a sharp shot with high-contrast edges. I turn my slider down to between -0.5 and -1.0, depending on the shot and the particular camera model used. I prefer to do my "capture sharpening" later.

Seems that way to me too, and it's looking more and more like a good idea to leave "capture sharpening" until later - it's easier to add than to subtract.

[Manfred M]

Seems that way to me too, and it's looking more and more like a good idea to leave "capture sharpening" until later - it's easier to add than to subtract.

I turn off capture sharpening in my raw convertor for that very reason. The default settings work fine for an "average" image (whatever that might be), but fail miserably for other images. My other reason for doing so is equally pragmatic.

I apply noise reduction to my images when I do the raw conversion, and this step needs to be done first, something that I can't guarantee is happening in the raw convertor. Sharpening noise is not a smart thing to do, which is why sharpening should occur after noise reduction.

The other trick to sharpening is that it should done when the image is at 100% size (not the scaled down version I see in the raw convertor).

[DanK]

The other trick to sharpening is that it should done when the image is at 100% size (not the scaled down version I see in the raw convertor).

I haven't checked ACR for this, but it is trivial to enlarge the image to 100% for sharpening in Lightroom. It provides a small preview automatically, but I just use the pull-down menu at the top left to blow up the entire image, and then I choose the area(s) I want to examine while sharpening.

[Manfred M]

I haven't checked ACR for this, but it is trivial to enlarge the image to 100% for sharpening in Lightroom. It provides a small preview automatically, but I just use the pull-down menu at the top left to blow up the entire image, and then I choose the area(s) I want to examine while sharpening.

In my view, neither ACR nor Lightroom should be used for sharpening, just because you cannot control the order of how the software applies the changes. I do all my sharpening in Photoshop. I find ACR is a bit better than Lightroom because the default viewing window is larger.

[george013]

In my view, neither ACR nor Lightroom should be used for sharpening, just because you cannot control the order of how the software applies the changes. I do all my sharpening in Photoshop. I find ACR is a bit better than Lightroom because the default viewing window is larger.

Sequence is important?

George

[xpatUSA]

The other trick to sharpening is that it should done when the image is at 100% size (not the scaled down version I see in the raw converter).

+1 to that.

I often find 200% or even more zoom (unsmoothed of course) helpful in that regard. Easier to view halos and other artifacts . .

[Manfred M]

Sequence is important?

George

Yes - sharpening should be done after noise reduction, otherwise one enhances the areas where digital noise is visible, making the issue worse. The process should be reduce noise, then sharpen.

[george013]

Yes - sharpening should be done after noise reduction, otherwise one enhances the areas where digital noise is visible, making the issue worse. The process should be reduce noise, then sharpen.

It just reminds me to that other thread where was posted that sequence isn't important in a parametric editor. So now I'm a bit surprised.
NEF Processing

George

[Manfred M]

It just reminds me to that other thread where was posted that sequence isn't important in a parametric editor. So now I'm a bit surprised.

George

We can't control the sequence of how things are applied in a parametric editor; that is something that the programmers have decided for us users. That is effectively why sequence is not important (and this is not ideal, in my opinion).

From a mathematical standpoint (which is what both parametric and pixel based editors use), so long as the operations are commutative (i.e. order of operations does not matter; for instance addition and multiplication); sequence is not important. The moment this is not the case, order is indeed important, hence my general uneasiness with all parametric editors.

That being said, most computer programmers have a strong math background, so hopefully they have designed their code in such a way where this is taken care of properly.