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Author Topic: Anyone use PTGui Pro?  (Read 17811 times)
Justan
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« on: March 16, 2010, 03:01:59 PM »
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I recently bought this program, and while it offers much more control for stitching than does CS3, it does not appear to offer a lot of control for vignetting correction. But I could be missing something.

I found a reference for the control it does offer here: http://www.ptgui.com/examples/vigntutorial.html

I've followed the procedure above but it doesn’t do the job and definitely doesn’t do as well as does CS3.

This shortcoming appears compounded because PTGui doesn’t read ACR’s “sidecar” files. Due to this I perform vignetting correction in ACR then open and save the files as psd, then import them into PTGui. This is workable but adds PITA to the process.

What am I missing?

TIA!
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bill t.
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« Reply #1 on: March 16, 2010, 06:24:46 PM »
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I use the Pro version but never us those exposure correction things.

I do all the vignetting correction in ACR.  Since I almost always use F8 I have simple presets for each lens that include vignetting correction, chromatic correction, camera profiles, etc.  Then I export the pre-stitched panels as 16 bit TIF (not PSD).

In theory it's best to do as much correction as possible in the RAW conversion because that's where you have the most pristine image data.  I do as much contrast and color correction as possible in ACR.  If you toggle quickly from panel to panel while watching how the ACR histogram animates it's easy to equalize the panels, just keep on out that the histograms trend logically as you toggle between panels.
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wolfnowl
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« Reply #2 on: March 17, 2010, 12:37:41 AM »
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I use Autopano Pro rather than PTGui so I can't really help you there, but like Bill, I do my correcting in Lightroom before collecting the images for making the panorama.

Mike.
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ErikKaffehr
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« Reply #3 on: March 17, 2010, 12:57:34 AM »
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Hi,

Same here. But I seldom feel a need for correcting vignetting. In my view it is more important to fix chromatic aberration.Many lenses have some and it cannot be removed from the assembled panorama.


I have some write up on my technique here: http://echophoto.dnsalias.net/ekr/index.ph...a-and-stitching (needs an update)

Best regards
Erik


Quote from: wolfnowl
I use Autopano Pro rather than PTGui so I can't really help you there, but like Bill, I do my correcting in Lightroom before collecting the images for making the panorama.

Mike.
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Justan
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« Reply #4 on: March 17, 2010, 08:21:43 AM »
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Quote from: bill t.


Thanks Bill,

I looked into ACR presets for the first time after reading your note. That appears to be the key to simplifying the process.

> I do all the vignetting correction in ACR. Since I almost always use F8 I have simple presets for each lens that include vignetting correction, chromatic correction, camera profiles, etc.

Where or how do you get the information for correction, profiles…?

> I do as much contrast and color correction as possible in ACR.

That has to be a fairly evolved skill to do with pre-stitched panos. Unless I took a lot of notes along the way I’d have a hard time doing this with a dozen raw files and getting consistent results.
 

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Justan
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« Reply #5 on: March 17, 2010, 08:29:21 AM »
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Quote from: wolfnowl
I use Autopano Pro rather than PTGui so I can't really help you there, but like Bill, I do my correcting in Lightroom before collecting the images for making the panorama.

Mike.


Thanks Mike!

Okay how does one make corrections to pre-pano images and get uniform  results?

I tried Autopano Pro but went with the other guys.
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Justan
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« Reply #6 on: March 17, 2010, 08:51:27 AM »
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Quote from: ErikKaffehr

Thank you Erik!

The article you referenced was a good one and I'm gonna have to get an L bracket. The article you referenced in your write up was excellent and I'm duplicating the link here for future readers on the topic: http://luminous-landscape.com/forum/index....=36973&st=0
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bill t.
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« Reply #7 on: March 17, 2010, 01:30:07 PM »
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You get correction settings for vignetting by first photographing a perfectly flat, perfectly evenly lighted surface. Some use the north sky on a clear day.

In ACR go to the Lens Correction tab which is the picture of the cutaway lenses. Adjust the Amount and Midpoint sliders until when you run the cursor from corner to corner, the RGB numbers displayed by ACR change the least, or not at all. Hint...for my old Nikon D2X APS sensor, Amount was almost always 12, and Midpoint 0. For fullframe sensors expect larger numbers. It just might be the case that the best vignetting numbers are where the Midpoint slider has the smallest possible number that works.

On to Chromatic. Pick a raw file shot on a contrasty day with lots of contrast or texture near the corners. If you can find a disgusting white cigarette butt near the edge of the image, that's almost the perfect Chromatic Aberration target. Note that you will probably see red or cyan halos around bright objects. Adjust the Fix Red/Cyan Fringe slider to minimize the halos, noting that you can shift the halo from one side to the other. Balance out the Red and Cyan halos as best you can. Then go on to Fix Blue/Yello Fringe the same way. Check some areas more towards the center as well, you may have to compromise slightly between best correction on the edge and midpoints. Hint...for my wackiest wide angle its -28 or Red/Cyan, and -20 on Blue/Yellow. But my hyper-wonderful 55 Micro needs no adjustment.

Camera Profiles is a whole other thing, but lacking a specific profile for you camera just pick "Camera Standard" instead of the default "Adobe Standard." It's really a matter of taste, "Camera Standard" is prettier and I like pretty things.

LOTS of correction is possible in ACR. And since you are working as close to the original camera data as possible, you will do the least damage to image quality by making your big changes here, rather than later on when the data has already been scrambled a bit by RAW to TIF conversion.

Now the thing with panos is, you are covering very wide angles of view and one side of the image is almost always going to be brighter than the other. So I just load all the pano panels in ACR, pick one towards the center, get my basic "look" down, then work out towards either edge fudging the controls around to more or less make the outlying panels play nice with the look of the central panel, but without clipping. This means every panel may wind up having the different values.

For instance on Exposure, the central panel may be "0.0", but moving towards the brightest side of the image I have brightnesses of -0.1, -0.2, -0.2, -0.25, -0.3...that kind of stuff. For a newbie, just get that central image balanced, copy those settings to all the panels, then start moving out towards the sides trying to concentrate mostly only on Exposure. When the exposures on all the panels looks about as good as you can get it, then you can go back and mess with the other settings. An important concept is to make sure that as you adjust any of the sliders, that adjustment probably wants to "trend into" the same setting for the adjacent panels.

When evening things outs, it is helpful to watch how the histogram animates as you flip from panel to panel. Rather than making huge morphs, it's change should subtly change when going between adjacent panels (unless the actual contents of adjacent panels changes radically). Helps give you an idea how you're doing. Also ACR displays RGB values, it is helpful to compare the RGB values of pieces of sky that will overlap in adjacent channels.

Or you can just forget the last few paragraphs and shoot all your panos facing north at noon.

OK, so there you are. Gotta coat some prints.
« Last Edit: March 17, 2010, 01:35:14 PM by bill t. » Logged
wolfnowl
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« Reply #8 on: March 18, 2010, 01:12:53 AM »
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Quote from: Justan
Thanks Mike!

Okay how does one make corrections to pre-pano images and get uniform  results?

I tried Autopano Pro but went with the other guys.

I use Lightroom's 'AutoSync' function, so any changes made to one images are automatically made to all selected.

Mike.
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Justan
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« Reply #9 on: March 18, 2010, 09:26:44 AM »
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> In ACR go to the Lens Correction tab which is the picture of the cutaway lenses. Adjust the Amount and Midpoint sliders until when you run the cursor from corner to corner, the RGB numbers displayed by ACR change the least, or not at all….

Thanks very much for taking the time to detail the steps!!! I did some tests using a clear post sunset sky (looking east) with 2 lenses at minimum aperture and found that 12 0 and 9 0 removes the vignetting for both, at least as ACR reads them.

I still have to do the workup for chromatic adjustments.

I’ll refer back to this great tutorial when working up my next pano.

One more question: is this kind of correction (vignetting, chroma) suitable for a zoom lens at all focal lengths or just one?

I understand that vignetting will change depending on the aperture, and am guessing it will also change as the focal length increases. Is that correct?

Thanks again!

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Justan
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« Reply #10 on: March 18, 2010, 09:27:36 AM »
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Quote from: wolfnowl
I use Lightroom's 'AutoSync' function, so any changes made to one images are automatically made to all selected.

Mike.

That is clearly a very useful feature!
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bill t.
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« Reply #11 on: March 18, 2010, 12:24:20 PM »
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Quote from: Justan
One more question: is this kind of correction (vignetting, chroma) suitable for a zoom lens at all focal lengths or just one?

I understand that vignetting will change depending on the aperture, and am guessing it will also change as the focal length increases. Is that correct?
Vignetting and chromatic aberration and every other optical annoyance will change over the range of a zoom lens.  And also with aperture.  Zoom lenses are wonderful teaching aids for those wishing to understand optical aberrations.  No biggie, if you slap down those aberrations in one frame of your pano set, you can use the ACR "Select All" and "Synchronize" buttons to copy the fix to all the panels.

It's no big deal to work up new aberration settings for each pano.  Presets should not be viewed as a holy grail worthy of struggle.  I have presets for all my primes, but sometimes have to fudge them for scenes that are especially brilliant or have especially prominent specular highlights.  Oh, and in low contrast scenes chromatic can show up as very subtle off-color blushes around bright to dark transitions, don't let those slip by.

So you're shooting panos with a zoom, eh?  That's just wonderful.  
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Thomas Krüger
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« Reply #12 on: March 18, 2010, 12:45:15 PM »
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In PTGui switch to "Advance" and to the tab "Exposure / HDR" to open the automatic exposure and color adjustment. However, I prefer to correct with the raw conversion.
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Justan
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« Reply #13 on: March 18, 2010, 04:07:08 PM »
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> Vignetting and chromatic aberration and every other optical annoyance will change over the range of a zoom lens. And also with aperture.

Thanks.

> Zoom lenses are wonderful teaching aids for those wishing to understand optical aberrations.

All right then….. once I start printing the projects at bigger than 23.5” on the long side, I'm sure I have a cornucopia of new horrors waiting. But on my single non-pano frames, s’not so bad at the limit of the printer.

> No biggie, if you slap down those aberrations in one frame of your pano set, you can use the ACR "Select All" and "Synchronize" buttons to copy the fix to all the panels.

Ding! Ding! Dingngngng!! We have a winner! THAT is how you do common work on pano frames in ACR without taking notes on every step of every frame. D’oh! It wasn’t until yesterday that I opened more than one frame in ACR at the same time….. so the light goes on however low wattage. Now I understand how to do common work in ACR. Oy for the delight! The giddy sense of climbing above another ridge line!!

> It's no big deal to work up new aberration settings for each pano.

Now that I have a sense of it, I agree

> Oh, and in low contrast scenes chromatic can show up as very subtle off-color blushes around bright to dark transitions, don't let those slip by.

I've seen this in forest shots. A lot. It is so cool to have stumbled upon a solution!

> So you're shooting panos with a zoom, eh?

Okay there smart fella, what do you do? I mean other than taking a crew with you? Do you do studies where you decide what FL to use, then come back with the closest prime to that? The alternative is to schlep a bunch of fixed length lenses everywhere….
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Justan
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« Reply #14 on: March 18, 2010, 04:07:36 PM »
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Quote from: ThomasK
In PTGui switch to "Advance" and to the tab "Exposure / HDR" to open the automatic exposure and color adjustment. However, I prefer to correct with the raw conversion.


Thanks. I'm familiar with that adjustment. But it didn’t do the job.

From what I've learned in this thread using ACR or LR is the only way to accomplish the task. Unfortunately.
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bill t.
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« Reply #15 on: March 18, 2010, 04:18:52 PM »
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Quote from: Justan
Thanks. I'm familiar with that adjustment. But it didn’t do the job.

From what I've learned in this thread using ACR or LR is the only way to accomplish the task. Unfortunately.
The automatic equalization is intended for point & shoot jpeggers with cameras stuck in AUTO mode.  It works about as well as Russian->English translation software.  Equalizing panos may be last thing in photography that still requires the intervention a human mind.
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Justan
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« Reply #16 on: March 18, 2010, 04:51:42 PM »
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Okay well I must be missing something obvious in the use of PTGui.

I followed Bill’s excellent tutorial and used ACR to correct for vignetting. The results were a vast improvement – not perfect but a vast improvement. I then used another part of my newly learned skill set to make the same changes on every image in the pano (select all and syncronize). After that I used ACR to create tif files out of these nicely improved images.

After that I did 2 tests with these tif files.

In one test I imported the files into CS3 and did a photo-merge. No other changes. a jpg of the result is below



Next I imported the exact same tif files into PTGui. I walked PTGui through it’s default steps. In other words I made no modifications. After the stitch completed I had PTGui create a tif of the merged files.

I opened this file in Photoshop and made a jpg identical to the first one. Again no modifications were made.

The result is below.



PTGui appears to be is doing something to ?exaggerate? the effect of vignetting….

what the Huh
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bill t.
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« Reply #17 on: March 18, 2010, 07:25:11 PM »
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Any sensible panographer wannabee would shoot his first pano on a sunny day looking north.  But Nooooo....

Lots of things going on.

That's just bad blending, made worse by a set of pano panels that have naturally huge sky variations.  What version of PTGui are you using?  The PTGui blender improved radically a few versions back, but was not so hot before that.  OTOH the Photoshop blender is one of the best, although the stitcher is still not quite there.  One option is to work the images a lot more in ACR, then export from PTGui as a LAYERED .psd or .psb and let Photoshop to the blending, then flatten.  Did you use Smartblend, which is no longer the best choice.

OK, so it's a really tough shot, the left side is a lot brighter than the right, partly because of sun direction.  And it just got darker while you were shooting, Magic hour panographers must be quick like a bunny.

Try to equalize the images a lot more in ACR.  Get the center panel looking great, then working meticulously outward from that, make the other panels look more like the central panel, while possibly keeping some sense of the scene being a little brighter on one side.  Right now your image-to-image sky variations are little too challenging for the blender, try to minimize variations in the sky.  This means you would have to force the left side panels to look darker, and the right side panels to look lighter, but don't over-homogenize.  You need to effectively time compress the scene a bit.

Or if a lazy panographer could get the sky nicely selected, he could replace the ugly sky with a nice, even gradation using representative bright and dark samples from the existing sky.  Partial transparency can sometimes help with credibility in these cases.  A cloudless sky invites Photoshop mischief.

Best remedy...shoot it again when the light is changing at a slower rate, which would be a little earlier or a little later.  Looks like you shot during peak rate of change, which happens just before and after sunset.  And shoot faster.  When I shoot panos like this I start shooting a few minutes before sunset, then keep going for several minutes after.  Same pano, over and over, HDR and all.  Out of the 1000+ exposures will emerge one set that is Just Right.

To verify...you are exporting 16 bit .TIF's from ACR, loading them into PTGui, then outputting a .psd from PTGui.  In PTGui you probably want to select PTGui Blending on a single layer, or an unblended set of layers (one layer per original camera file) for blending in PS.

Another quick thought...balancing out heavily saturated skies like that is very difficult, almost any change in scene contrast will produce exaggerated affects in the sky.  You could think about processing each of the panels twice, one for the ground, and once for the sky, then using masks in Photoshop pick out the best parts of each.  You would first need to process each of those two sets in PTGui using the Template function made from the first set to get the second set to line up exactly.  Don't create a new set of control points for the second set, use the template from the first which will use those original control points and guarantee a good overlay.

If I had received advice like this when I first started doing panos, I wouldn't have understood a word of it.  Sorry.  I'm trying.
« Last Edit: March 18, 2010, 07:42:58 PM by bill t. » Logged
JeffKohn
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« Reply #18 on: March 19, 2010, 11:33:08 AM »
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Even so I would expect PTGuil to do a better job of blending than Photoshop. You should be able to get a better result from PTGui. Try using a different blender, or if you used any of the exposure correction options turn those off.
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Luis Argerich
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« Reply #19 on: March 19, 2010, 11:45:47 AM »
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Wow, I've never had such a bad output from PtGUI. As mentioned smartblend used to be the good blender but not enymore. Make sure you don't have it on accidentally.

What is the overlap between frames? Maybe the blender can do a better job with a more generous overlap? I normally overlap between 20% and 40% depending on the conditions and the scene.


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