Little info about focus stacking algorithm used in Photoshop

[nik5CFE]

Hi,

i'm currently a student interested in focus stacking software.

Of course, the details of focus stacking algo's implemented in Photoshop

are not public avaible due to commercial reason;

anyway i cannot find even some basic "generic type info" about it;

(i'm quite sure i've not searched in right place, so maybe anyone could give me some suggest about)

I mean,some of other major stacking software write something about

procedure used, at least from a general point of view.

For example is well documented that Helicon software uses three different algorithms,formally reported as "Method A, B, C"; and similar, Zerene Stacker software give some info about their two ways to stack images (reported as "PMax" and "DMap"  methods).

- Is photoshop using some procedure which we can "assume more or less like any of A/B/C or PMax/DMap" methods?

- Is photoshop using some procedure with different and specific logic  respect zerene/helicon procedure?
-Is there some article/technical docs from official adobe teams about the topic ?
Every info about focus stacking algorithm implemented is welcome, obvioulsy in general terms.

[Ed Merrin]

Hi nikSCFE,

Looks like you never got an answer to your question. Well, I don't know either. It would be nice to know what generic type of algorithim Photoshop uses but it seems closely guarded. It wouldn't change what you do becsue you don't have options anyway, but it might be instructive if you are comparing software packages. Of course, the same might be said for ON1 and Affinity, as they are also full editing packages that do focus stacking. I don't think they state what type of algorithim they use either.

Carry on!

Ed Merrin

[D Fosse]

To be honest, Photoshop's focus stacking isn't particularly brilliant and the general consensus is that Helicon Focus and Zerene Stacker both do a better job. So I'd recommend using those if you can.

[Ed Merrin]

Thanks for the input!

Actually I've moved over to Helicon Focus for the most part. I did a lot of comparisons. Most of the time they are more or less the same, but Helicon is faster and you can experiment with dropping frames, changing settings, etc and re doing in a flash. I haven't tried Zerene but I've seen some video demonstrations. Also, artifact problems are less with Helicon, depending on the settings. But when I get them I use Photoshop most of the time to fix them.

Ed Merrin

[D Fosse]

Focus stacking isn't necessarily as straightforward as it seems. If you focus "traditionally" by moving the lens elements, you'll get a variant of parallax error with shifting viewpoint, and so you get fuzzy areas that aren't precisely overlapped by sharp areas. The question is what to do with those areas. Photoshop will just leave them as-is, with no attempt at "reconstruction".

The problem more or less goes away if you use a focusing rail that focuses by moving the camera body instead of the lens, but that isn't as easy to do with modern digital equipment. In the old days you'd use a reversed 50mm on a bellows system.