Focus Merge of Four Tiff Files - Fuzzy Band

[AlanRab]

Hi all. Frequently, when I focus merge, I see a strip at the bottom edge or band that looks not only out-of-focus, but as if it has digital artifacts (as in vertical banding). The source photos do not contain this band. I typically crop out that portion of the photo while mourning a loss of pixels. 🥺

Is there something I can do to avoid this issue? (Photo attached of a lower portion of a focus merge of four tiff files.)

[Old Bruce]

H @AlanRab,

Welcome to the forums. 

When the application does its focus merge some of the images are rescaled larger or smaller (I truly do not know which) then masked and this is most likely caused by that.

Compare the size of the four TIFF's dimensions in Pixels with the finished document's size in Pixels.

[AlanRab]

@Old Bruce Hello, and thanks for your response. I checked the four source tiffs and found they are all of the same pixel dimensions, as well as the same as the focus-merged tiff. To add to the puzzle, but somewhat of a relief, I compared the bottom-edge strip/artifact in the focus-merged tiff to the RAW source photos. The bottom-edge strip is actually OUTSIDE the image shown in the RAW source photos, as if the edge pixels were stretched out. My relief stems from the fact that the focus-merged tiff doesn't actually cut off any parts of the original image.

However, since the bottom-edge strip in the focus-merged tiff is within the same pixel dimensions as the source photos, I might conclude that the strip is an artifact that is filling in pixels (in a distorted way) on some of the images that have been focus-shifted (not sure I'm using the correct term).

Am I on the correct track?

Edited September 4, 2022 by AlanRab

[Old Bruce]

31 minutes ago, AlanRab said:

However, since the bottom-edge strip in the focus-merged tiff is within the same pixel dimensions as the source photos, I might conclude that the strip is an artifact that is filling in pixels (in a distorted way) on some of the images that have been focus-shifted (not sure I'm using the correct term).

Am I on the correct track?

I would say yes.

The few times I have used the focus merge it was just to check it out. While setting up to to take the pictures I expected to be cropping the final image so I have  never actually looked at the edges of my experiments.

[NotMyFault]

1 hour ago, AlanRab said:

Am I on the correct track?

Absolutely. This behavior has been reported & confirmed before.

After focus merge, you may need to crop off areas where no sharp pixels where available. This happens if the source images do not cover sharp images for the complete area. This can happen.