Affinity Photo for Windows: Focus Stacking

[JohnRostron]

I have been trying out the Beta version of Affinity Photo for Windows. So far for general-purpose editing it looks good. One thing that it does not do is to acquire an image from a scanner. In the Help files it tells you how to do this, but the menu item to acquire is missing. I would guess that this was there in the Apple version, but not yet implemented in the Windows version.

I noted that this offers Focus Stacking (or Focus Merge as it calls it). I created a number of stacks of 4-7 images of spindle tree fruits and of a fossil whelk to try this out. It works - and works well - but it takes ages! The resulting image is good, comparable with the PMax output from Zerene Stacker. In Affinity the stacking and Merging took 10 minutes for six images! Zerene took 2-3 minutes to produce both the PMax and Dmap images. Here is the output from Affinity:


This is the un-retouched output, just resized for the web. It is virtually indistinguishable from the Zerene Pmax. Affinity does offer output retouching if necessary, but this image did not need any. If you wanted to stack without Zerene or Helicon (or Photoshop), then this works well if you can wait.

Comments welcome.

Edit

I have just downloaded the updated version, and the stacking time is now much better. The six-image stack above took 90 seconds!
John

[Sonic4Spuds]

I haven't played with focus stacking software, so I'm not sure if all of them produce this, but I notice a halo effect, likely due to the blurred parts of exposures next to in focus ones not being entirely removed. Thanks for the heads up.

[DanK]

I haven't played with focus stacking software, so I'm not sure if all of them produce this, but I notice a halo effect, likely due to the blurred parts of exposures next to in focus ones not being entirely removed. Thanks for the heads up.

Those halos, which seem fairly pronounced in this image (it's hard to tell at this low resolution) are a common problem in stacking, regardless of the software, although the severity varies depending on the software. It's caused by parallax. You will therefore see it primarily when surface is quite far, front to back, from the surface behind it. It's usually at least partially fixable by retouching from one image on the stack, but often it isn't completely fixable even with that. I stack exclusively with Zerene, which as John noted has two different stacking algorithms. DMap does better at preserving color, but it is prone to more severe haloing. PMax produces smaller halos and preserves more detail. I often retouch DMap composites from Pmax composites, and that is usually enough to reduce haloing either entirely or enough that the results are acceptable. However, how well you can get around this depends on the characteristics of the material you are photographing.

[Sonic4Spuds]

Thanks for the more detailed info Dan, I figured it had to be a problem for most stacking software, but it's good to know a little more about it.

[JohnRostron]

Please see my edit to my original post.

I did say that this was the un-retouched output from Affinity. It does offer a repair facility. You can use any of the original images as a clone source to correct such errors. I have now used this to remove the fringing from the right-hand edge of the leaf at the bottom. This was easy enough once I had identified which of the original images was sharp. The response in showing the selected image was a bit sluggish.


As Dan says, Zerene (and Helicon) offer alternative algorithms which Affinity does not. The output does look more like the Pyramid (Pmax) algorithm of Zerene. Zerene is my go-to package for focus stacking, but I am posting this for those looking for an alternative within a photo-editor.

John

[DanK]

John,

I hadn't even noticed the halo at the bottom. I hadn't expected to see it there. Was there haloing there with PMax as well? What I was looking at--which is much harder to see at this resolution--is the haloing around some of the berries and flowers.

Dan

[JohnRostron]

This is the output from Zerene Stacker PMax algorithm. There is less evidence of haloing in this.



I should add that the original images were taken by hand-cranking the focus ring. No automation! I tried to ensure that all the
actual fruits were in focus without worrying too much about the leaves. The red parts are the inner fruits and the cream parts the outer fruit husk.

The main thrust of this thread is to show that you can do focus stacking using Affinity Photo, which is currently in a free beta for Windows and is likely to cost £30-£40 in its final form. Zerene is $89 (around £50-£60). For those stacking on a shoestring (now, there's a thought), I think it is a good option.

John