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Author Topic: Stitching and "Focus stacking" combined?  (Read 6788 times)
BartvanderWolf
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« Reply #20 on: May 16, 2012, 02:50:40 AM »
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I have a noob question:

Instead of using stacking software or algorithms, why don't people use masking in photoshop to 'layer in' each plane? Won't that give precise results, or is there a downside?

Hi Sareesh,

I agree with Bill. When you focus at different distances, the magnification factor of the projected image on the sensor will change. Therefore the software must do several things, resize each image, align the images in the stack, adjust variations in exposure, and select/mask the sharper portions of each image, and blend the selection between the successive images to a seamless transition.

That's a lot of (tedious) work to do by hand, especially when the number of images in the stack increase. I've done macro images with more than 100 stacked images each. What's more, programs like Helicon Focus use better resampling algorithms (Lanczos) for these small scale image size adjustments than Photoshop (bicubic) does, and they can use things like a dustmap to automatically remove the shadows of sensor dust particles, which will otherwise leave very noticeable trails of spots due to the resizing.

Cheers,
Bart
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Sareesh Sudhakaran
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« Reply #21 on: May 16, 2012, 09:43:22 AM »
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Thank you for explaining, Bill and Bart. I didn't consider the agony of having a 100 images to blend in!
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John R
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« Reply #22 on: May 16, 2012, 07:55:56 PM »
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I tried Zerene and Helicon, each left ghosting. And yes this was for macro work of flowers, mostly creative work. At micro levels, you have to be discerning about what to include in or out of focus. It's a different proposition for landscapes. You mostly want everything in focus. What I did not try was combining large numbers of images. I used only 5 or 6 at most. I am just going to have use the old method of trying different focal points and different apertures to get what I want. With film slides, you didn't waste film!

JR
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BartvanderWolf
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« Reply #23 on: May 17, 2012, 02:44:27 AM »
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I tried Zerene and Helicon, each left ghosting. And yes this was for macro work of flowers, mostly creative work. At micro levels, you have to be discerning about what to include in or out of focus.

Hi John,

Maybe therein lies the problem, just missing the required shots for a smoother transition. The usual issue is with occluding features. When focusing on features further away, foreground features become somewhat transparent and the blending has trouble deciding which sharp image to use, foreground or background. HeliconFocus' Method B (using a depth map) is better at getting the edges right, because Method A uses averaging which is better for surface structures. The recently added Method C (pyramid) may also work well. It can work well if you combine parts of the the A/B/C output by using the retouching functionality of HF Pro. Zerene also offers  retouching capability if I remember correctly.

Quote
It's a different proposition for landscapes. You mostly want everything in focus. What I did not try was combining large numbers of images. I used only 5 or 6 at most.

Depending on the magnification factor, that may be too few. Based on the magnification factor, you can use the (slightly less accurate, but accurate enough) DOF approximation formula for close-up and macro photography, which uses the magnification factor as input. Your sensor size in relation to the size of your object will give you the correct magnification factor to use. The CoC to use in that formula equals the sensel pitch, if you want seamless sharpness per pixel from front to back. If you are going to output at less than pixel per pixel size, you can increase the CoC proportionally.

Cheers,
Bart
« Last Edit: May 17, 2012, 02:27:45 PM by BartvanderWolf » Logged
bill t.
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« Reply #24 on: May 17, 2012, 11:30:02 AM »
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Basically, if you have nearby objects like trees with bare branches where you can see the horizon through openings between the branches, you need to shoot as many focus planes as possible to keep the ghosting down.

However, ghosting is not always bad.  Sometimes very subtle ghosting around nearby vegetation can help separate it from more distant textured background in ways that is really not objectionable in the print.
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Michael H. Cothran
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« Reply #25 on: May 18, 2012, 10:58:15 AM »
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I have a noob question:

Instead of using stacking software or algorithms, why don't people use masking in photoshop to 'layer in' each plane? Won't that give precise results, or is there a downside?

Using Auto-Align will match up your layers so there are no offsets.
There are many photographers on the Nature Photographers Network - http://www.naturephotographers.net/enter.html
that are churning out superb results using combinations of stacking, stitching, and exposure blending.

NPN member Marc Adamus comes to mind - http://www.marcadamus.com/ .

NPN member Tony Kuyper has produced some excellent actions for creating Luminosity Masks - http://goodlight.us/ , which are quite beneficial. Check out his tutorials.

NPN member Pat Sampson, who is "taking a break" has some exquisite florals that are stacked - http://www.naturephotographers.net/imagecritique/ic.cgi?a=up&pi=PATSAMPSON&ns=1&CGISESSID=bb8866b4fac309c6645e8ea0aa50bf59&u=24287
My favorite Pat Sampson image is titled "Red Tulips" five rows down.

Here's one by NPN member Craig Strand I really like - http://www.naturephotographers.net/imagecritique/ic.cgi?a=vp&pr=179350&CGISESSID=bb8866b4fac309c6645e8ea0aa50bf59&u=23948

Here is a link to a few more NPN stacked florals - http://www.photoportfolios.net/portfolio/pf.cgi?a=sp1&gr=4
Note - select "Flowering Plants," then type "image stack" in Optional Keywords.
                                                                  
Developing good skills through practice can produce amazing results.
« Last Edit: May 18, 2012, 11:09:17 AM by Michael H. Cothran » Logged
Sareesh Sudhakaran
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« Reply #26 on: May 18, 2012, 10:44:05 PM »
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Thanks for the links, Michael. Will check them out.
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prairiewing
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« Reply #27 on: May 19, 2012, 09:56:04 AM »
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Thanks Michael, I hadn't looked at that site for years.  Great work.
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Pat Gerlach
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« Reply #28 on: May 19, 2012, 11:17:40 AM »
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Great thread for us noobs: thanks, everyone. This explains some of my soft landscapes and I look forward to trying these techniques.
Scott
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BartvanderWolf
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« Reply #29 on: August 25, 2013, 08:34:07 AM »
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Hi folks,

Just to let you know, I've started a thread about a new web-based tool that I created. The 3rd section of the tool also assists in calculating the required number of slices, and their focus distance, for the creation of a perfectly focused stack. The results can also be a bit sobering for those who want everything in perfect focus, but you can always reduce your output size ... Wink

Cheers,
Bart
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nma
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« Reply #30 on: August 25, 2013, 10:37:14 AM »
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When considering combining focus stacking and exposure blending for Canon SLR camera there is another approach to consider which can more or less automate your work  in the field. I am talking about dslr Controller, an APP that runs on later versions of the Android operating system, meaning your phone and tablet. It is in beta ($9) but it appears to work very well as is. This APP is not a one trick pony. It can bull focus from point A to B, automate and extend HDR capture in many exposure steps, do both at the same time (lots images), it will calculate the number of exposure steps needed for focus stacking with certain restrictions. With a tablet and a USB extension it will remote most of the functions of your Canon SLR to the display on the tablet. You can use various touch commands on the tablet to change f stop, ISO, etc. See http://dslrcontroller.com/ for details. Magic lantern can do similar things (plus more) on certain Canon dslr's and it is free. Pros and Cons. I tried both and thought dslr controller was better for the focus stacking kind of apps. 
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BartvanderWolf
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« Reply #31 on: August 25, 2013, 10:54:33 AM »
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I tried both and thought dslr controller was better for the focus stacking kind of apps. 

Hi,

Indeed, Dslr Controller gets good reviews from users. Another alternative is Helicon Remote for Android (also available for Windows and Mac). It can also interface with e.g. the motorized StackShot focus rail.

Cheers,
Bart
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Isaac
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« Reply #32 on: August 25, 2013, 12:05:34 PM »
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I tried Zerene and Helicon, each left ghosting. And yes this was for macro work of flowers, mostly creative work. ... What I did not try was combining large numbers of images. I used only 5 or 6 at most.

For close-up work (not macro) I'd need more like 30-50 images.

Back in June I made series of close-up flower images and was very disappointed with the ghosting around each petal in the merged image. It was a frustrating couple of weeks, of blindly working through different apertures in the hope that might have something to do with the problem. I must have had hay-fever.

Once I'd exhausted all the possibilities I finally re-read the Enfuse documentation and found the very clear instruction that if the merged image showed visible seams then use different contrast-edge-scale and contrast-min-curvature parameters. Doh.

And lo, ghosting was reduced to a scary story, and there was much rejoicing.
« Last Edit: August 26, 2013, 12:07:53 PM by Isaac » Logged
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