elf wrote:I'm impressed that you even were able to stack that many images in PS. My system fails around 35
I don't know what's up with that. My system doesn't seem to have a hard limit; it just starts doing lots of I/O. I think Task Manager showed around 40 GB read/write on this one.
Chris S. wrote:Photoshop seems to have messed up not only the hard stuff I'd have expected it to struggle with, also some things that would would be easy, such as bristles on a plain background.
Yes, that is interesting. I didn't expect it either, but having seen it, I think I know what's happening. Photoshop seems to be using a feature-points method of alignment, which is typical for panorama registration. That works pretty well also for low magnification stacks where every frame shows basically the same recognizable stuff, albeit focused differently. But in these high mag stacks, most of the frame is full of featureless blur. Often the only thing that's in focus are the shafts of bristles. Those doesn't have recognizable features on two axes, only one. As a result, the feature-finder passes by those areas and instead locks onto strong features that are located elsewhere in the image. If the feature points that are found happen to be badly located, for example clustered in an area far away from the bristle, then slight errors in registering the feature points can cause large errors in registering the bristles. In other words, I suspect that Photoshop didn't even consider the bristles because they didn't meet its criteria for being important.
johan wrote:By coincidence, came across
this comparison. Author is a poster here
Ah yes, that comparison. I'm familiar with that work. Actually I know a fair amount about it because the author and I conversed for a while by email, and at my request he even sent me some of the stacks to look at myself.
stevekale wrote:How he can rate the CS5 version of the last image a the best is beyond me. Did he even look closely at the results?
Well, different people have different criteria. I think he looked very carefully at the results. Certainly I did, and I agreed that the CS5 results were definitely better than ZS.
However, they were all pretty bad, by my standards. Photoshop was doing its usual trick of missing detail, while ZS PMax was doing its usual tricks of increasing noise and giving echos and halos everywhere there was motion or hard-edged OOF blurs. Initially he had only tried PMax. I suggested trying DMap with certain parameters, but the results were awful.
That was when I asked if he could send me some stacks to look at.
When I received the DVD, the basic problem was obvious. Rather than normal sequential stacks, he had shot unordered "heaps" in which the focus bounced around pretty much randomly. For example in his 5-frame "stack", the usual front-to-back ordering was 4, 1, 2, 5, 3 in his shooting order. In other words he shot pretty close, slightly farther back, then all the way back, then all the way forward, then almost all the way back again.
If you know how DMap works, you realize that random input practically guarantees awful results. But if you don't, then it's easy to reach other conclusions, as that author did.
ChrisR wrote:I suppose if you need a one-stick solution and don't worry about your details, then maybe PS is for you.
That's a vivid analogy, and pretty accurate, I think.
The great thing about PS is that it doesn't have any controls to learn. Once you know which buttons to click, just click 'em and the result pops out.
The bad thing about PS is that it doesn't have any controls in any case, so if what it does is not what you want, you're pushed all the way back to manual retouching. That's still not such a bad thing if you're dealing with a handful of images, even though it becomes wildly impractical with some kinds of work we do here at photomacrography.net.
2) Somewhere, sometime, in the forum, I thought Rik said that PS might be better for a particular type of subject.
Probably, though I can't recall for sure either. What I've seen recently is that Photoshop does well on small stacks, especially if you're more sensitive to tonal quality than to loss of detail. In addition Photoshop is easier to drive than the specialty stackers, and of course its stacking comes at no additional cost and is better integrated with the rest of Photoshop than the other tools are. I think the issue is not so much the particular type of subject, but the overall situation.
ChrisR wrote:If it was I who reprompted the subject, I was remembering, or misremembering:
1) A guy on a website did a test of some of Zerene, HF , PS and CZM(?) for landscapes. He did manage to make a bit of a mess with Zerene.
Rik's reworking of his files produced a result which was declared to be not as good as the PS output, and needing a lot more reworking.
I think the test I saw was just ZS, HF, and PS, not CZ. The Zerene outputs did look pretty bad. Most of the reason is explained above: PMax did its usual handling of subject motion, hard-edged blurs, and tonal changes, and the random ordering kept DMap from doing anything useful at all.
The key thing I did to "rework" his files was to just sort them into sequential order by focus point and run them through DMap using recommended settings. I also turned off Brightness correction to prevent any changes to pixel values, which seemed to be really important to him. The complaint then became that while the results were much improved, they weren't really any better than Photoshop's. No disagreement there, especially if the criteria don't count missing detail as being a significant flaw. Different strokes for different folks, and all that.
I will admit to being puzzled by the sweeping conclusions and strident tone of the comparison, but that's a matter for another day and a different venue. Probably best to think of it as an editorial opinion piece and move on.
--Rik
