Camera Raw/Lightroom: Merge to HDR - 'Mean Averaging'

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HDR.dngs are very powerful with their accurate colour and tonal response, but very often present artifacts like these when Deghosting is not applied:

When Deghosting is used, there are often abrupt transitions between areas with and without Deghosting. The areas where Deghosting is applied also present the noise of a single exposure or more!

A solution to get the noise reduction and smooth gradations of non Deghosted HDRs without their associated artifacts would be to have an option for 'Mean' like averaging when Merging to HDR. This would result in a image which would turn out like if you followed these steps: Load bracketed set as layers into Photoshop> Auto-Align (optional) selected layers> convert to Smart-Object> set stack-mode 'Mean' but with the power and flexibility of .dng
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Frenchfries

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Posted 2 years ago

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Steve Sprengel, Champion

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What does the Mean stack mode show for the above images in the problem areas you illustrate, above?


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Frenchfries

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Well, for example, in this first image, you can see the jagged edges of the HDR with a moving wave (No Deghosting applied)


With this second image (Stack mode Mean), while not perfect, it looks much less digital and more smooth.

I would never be able to print the jagged edges in the first image but definitely would print the Mean (or even Median) averaged version. This is also an obvious case with moving leaves which are often so jagged like in the OP.
To have this option in the versatile form of HDR.dng would be so very useful.
(Edited)
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Steve Sprengel, Champion

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Just because you can shoot HDR images of a scene doesn't mean that you should and expect good results.

To me the first image appears to have deghosting applied but I don't have any moving-wave images to try things with, myself.  If not the oddness might be a special case where if a channel is clipped then another image is used even if no deghosting is specified. 

Moving subjects like water and breeze-buffeted tree branches are not suited to stacking multiple images for HDR so deghosting is necessary to remove the multi-image effect; however, oftentimes the automated process guesses wrong leading to discontinuities and overbrightened noise.

An improvement would be a user-guided deghosting mask and a choice of which image to use to avoid the over-brightened noise areas. 

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It would be difficult for the user to see and manually mask the areas they want Deghosting applied to because the Preview Image is very limited in resolution. 2/3rds of the time, the artifacts mentioned occur at the pixel level in the fine detail, and thus would need magnification to manually mask out.
Also, if one intends to merge multiple HDRs for HDR-Pano.dng later, local manual Deghosting I imagine would be time consuming, but probably a necessity.
(Edited)
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I was working with a sunset-through-trees panorama a couple days ago, and the deghosting picked all but a few areas of branches to deghost and the photo that was picked was the darkest one, so what I ended up with was a noise tree branches except one little area that wasn't red with deghost-overlay. 

I envision being able to specify that the tree branches were all part of the deghosted area by painting more deghost-overlay as red and that a different photo be used for the branches to avoid the noise.  Obviously you might need to have more than two photos in the HDR to be able to pick one where the sky wasn't washed out but the not have it be the darkest one.

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I'd want to be able to use more or less of the tree branches as part of the deghosting area, and have some way to preview what I'm getting:

These were taken by my Galaxy S6 phone in Pro mode where there is control over ISO and shutter-speed but it was all hand-held so there was some camera movement. 

(Edited)
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Shooting raw DNGs with my phone was just for fun to see what would happen, but they do illustrate the point for more control over deghosting: