Zerene- slabbing - shine through

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lothman
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Joined: Sat Feb 14, 2009 7:00 am
Location: Stuttgart/Germany

Zerene- slabbing - shine through

Post by lothman »

Hello,
I have a problem in Zerene and hope there is a magic button to solve this :-)

when doing deep stacks of hairy objects like this fly shown here, on some spots I get problems when stacking with Zerene that some parts of deeper layer seem to shine through to the top layers.
combined_pmax.jpg
of course this could be solved by retouching what is quite a lot of work. So is there a possibility to tell Zerene when combining the slabs that parts with good contrast in a top layer "dominate" over a layer beneath in order to avoid this "shine through"

For example with slabbing I have these three layers with good separation.

top
layer_1.jpg
middle
layer_2.jpg
lower
layer_3.jpg

rjlittlefield
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Re: Zerene- slabbing - shine through

Post by rjlittlefield »

Sorry, there is no magic button for this classic "transparent foreground" problem.

If I knew how to implement one, I would surely do that.

--Rik

lothman
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Re: Zerene- slabbing - shine through

Post by lothman »

could you identify those pixel in each layer which were identified as "sharp" and combine this with the layer number. If that pixel -position was used from a layer above it no longer can be used from a layer beneath?

rjlittlefield
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Re: Zerene- slabbing - shine through

Post by rjlittlefield »

That's a version of the "reverse painter's algorithm".

It's one of several approaches that can all be summarized as "figure out what's in front, and only show that".

As a general approach it's obviously correct.

The difficulty lies in the details of deciding where the boundaries are. Include too few pixels from the foreground and background shows through; include too many and every bristle develops an annoying halo. If the halo is "lumpy", on what should be a smooth bristle, that's particularly annoying.

Making a set of decisions that is pleasantly close to correct is obviously possible, since even a quite young human can do that.

But exactly how the human does that is a bit mysterious. Watching myself retouch, the process seems to involve a lot of recognizing familiar 3D structures. "Ah yes, that's a smoothly curved bristle, and it's illuminated to be bright on one side, dark on the other." Sometimes I go back and forth between images at neighboring depths, to see how the appearance changes with focus.

I suspect that the problem could be knocked off by a properly trained convolutional neural network, running on the GPU to make it acceptably fast. But that's beyond my resources to develop, in several ways.

So, will something else occur to me? Possible, but since I've recognized the problem for well over 10 years, I am not optimistic about solving it any time soon. Probably somebody else will get it first.

--Rik

lothman
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Joined: Sat Feb 14, 2009 7:00 am
Location: Stuttgart/Germany

Re: Zerene- slabbing - shine through

Post by lothman »

Thanks Rik for this insight. I keep fingers crossed that there will be a managble "trick" for you.

In the meantime slabbing and retouching will do for me - I like Zerene a lot and of course your support is incredible, fast, friendly and last but not least competent. Thanks again :D :D :D

Lothar

rjlittlefield
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Re: Zerene- slabbing - shine through

Post by rjlittlefield »

Thanks for the kind words, and also for the question.

It is helpful to revisit these long-standing issues periodically.

While thinking about your question this time, I realized that slabbing may change the game in a way that makes automatic attack more effective. It's just a vague idea at this point, but maybe...

--Rik

lothman
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Re: Zerene- slabbing - shine through

Post by lothman »

rjlittlefield wrote:
Thu Jun 24, 2021 12:18 pm
While thinking about your question this time, I realized that slabbing may change the game in a way that makes automatic attack more effective. It's just a vague idea at this point, but maybe...

--Rik
I wish you good luck and I hope with the bigger regions of sharp areas of the slabs compared to single frames is something helpful for automation. This would make Zerene even more unique :wink:

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