dehaze artifacts

[Cupertino, Bangert]

Ok I'm not sure how I should term my problems with dehaze but artifacts seemed as good as any.  I'm trying to process my astro pictures and have found the dehaze effect to be very valuable as an almost one stop fixit.  My problem is where the sky meets the foreground.  I frequently get a light band above the foreground.  If instead of using the dehaze function use curves I don't see the same problem.  Of course curves doesn't work as well as dehaze baring the band over the foreground.  It seems like the foreground is bleeding into the sky.  As an experiment I took a raw astro photo into photoshop, masked the foreground and made a version with the foreground pure white, black, middle gray, and sample color from an area just above the foreground.  I saved these versions and then applied the dehaze effect to each version.  The band above the foreground was different in each version.  So it looks like LR is sampling over an area which will be a problem near the foreground.  My question is there anything I can do to fix this problem?  I did try to use the LR masked adjustment and it does restrict the effect to the masked areas but it's still sampling over into the masked areas.  If I could somehow exclude the foreground the dehaze would work as well as it does on the upper edges of the photo. 

[dj_paige]

I think if you post an example, it would be very helpful.

[Cupertino, Bangert]

I've added a straight raw to jpg and a jpg with dehaze set to 100.  The light band over the mountains is what I'm talking about.  The color of the band and the foreground changes in the four experiments I made changing the foreground to a solid color.  The 4 experiments all look the same above  1/3 of the way up the frame.

[Todd Shaner]

This looks like fairly normal behavior for a high Dehaze setting. I'd recommend using a lower Dehaze setting that doesn't produce the lightening and then use the Tone Curve, Clarity, and the other Tone controls to achieve the desired rendering. What will also help is to use a camera profile like Camera Faithful or Camera Neutral.

[Cupertino, Bangert]

This might be normal behavior but to my mind it is not necessary.  You don't see this behavior on the sides or top of the frame.  I think the dehaze effect would work perfectly in my case if it could only ignore the fact there is this boundary between the sky and foreground.  I'd bet that if the foreground was a straight horizon and I created an image that just had the sky the high dehaze setting would look just fine.  There's obviously some sampling across the border between sky and foreground so it would be nice if the adjustment brush with dehaze would act like the edge of the image when at the edge of the mask.

Unfortunately using a lower dehaze setting doesn't work very well.  Even at 50 it's obvious that a light border is there and as for the rest of the sky I might as well forget the dehaze effect for what little it's done.  There are other techniques for treating astro photos but it takes a LOT more work than using the dehaze effect.

[Todd Shaner]

https://forums.adobe.com/people/Cupertino%2C+Bangert  wrote

This might be normal behavior but to my mind it is not necessary.  You don't see this behavior on the sides or top of the frame.  I think the dehaze effect would work perfectly in my case if it could only ignore the fact there is this boundary between the sky and foreground. 

The Dehaze control accentuates WB differences, which is what you are seeing–It's the nature of the control. The WB temp in the sky area is very high and along the mountain edge it is much lower. Did you try using a lower contrast camera profile as I suggested (Camera Faithful or Camera Neutral)? That should reduce the WB changes significantly. Also makes sure to adjust the Luminace NR control at 1:1 view to eliminate visible noise in the image, which will cause the image to appear lighter at less than 1:1 view and in reduced size output files.

If you can post the raw file for download I'll take a look at it. Please Export the raw file to DNG with your settings and upload that file so I can what adjustments you're making.

[Cupertino, Bangert]

I tried to send a dng but it's evidently forbidden.  I did try the camera profile suggestions but they did very little.

[John Waller]

Most people upload their files to Dropbox or similar and post a link so we can download it.

[Cupertino, Bangert]

As per a suggestion here is a dropbox link to my raw file (I hope):

Dropbox - DSC01153.dng As

[Bob Somrak]

Why don't you use the BRUSH and change the temperature of the sky in that area.

[Todd Shaner · Accepted solution]

The DSC01153.dng file has a very warm 3550 WB temp As Shot indicating there was substantial sunrise light (i.e. lower in Temp) behind the mountain range. The picture is also very low in contrast indicating fog condition, lens flare, or perhaps an issue with a lens filter. So you have two issues with the original shot that are causing what you are seeing. IMHO LR Dehaze is doing a great job of removing the flare and bringing out detail in the star field. It's "accurately" showing the lower Temp sunlight over the mountain range.

As Bob Somrak suggested your best option is to paint in WB and Tone correction into that area to change it. The other option is to re-shoot the picture before sun rise. Here's an example using 100 Dehaze with Adjustment brush correction of the sun-rise light in the sky.

[Cupertino, Bangert]

I agree with much you have said.  The shot was made in an area with high light pollution.  However I still think the dehaze effect could do a better job if the adjustment brush had dehaze work only on the information in the mask.  I ran one last experient to demonstrate what I'm talking about.  I took my original raw image and cut out part of the sky one the left side almost touching the mountains.  I ran dehaze at 100 on the original and partial image.  I then took both images into photoshop and overlaid the partial over the full image.  I would be much happier if the adjustment brush with dehaze would only work with the information in the mask. 

Dropbox - DSC01153overlay.jpg

I would like to thank you for all your suggestions.  The dehaze effect is a great tool.

[Todd Shaner]

You can request this in the PS Family forum, which Adobe Engineering monitors:

Photoshop Family Customer Community

Place a link back to this post as a reference and here to the PS Family post.