This Photomerge capability in Photoshop is really quite fascinating. There's a tree near my house that keeps striking me as pretty with the afternoon sun on it, but I've never been able to photograph it because I don't have nearly a wide enough lens—and if I step back farther, the view of it is blocked by nearer trees. So just as a lark I went out yesterday and shot off nine frames with the Pentax K20D and 35mm ƒ/2.8 Macro. I made the shots handheld from quite near the tree—I stood maybe twenty feet from the stop sign on the right (see the last illustration below)—and I didn't do a very good job at all, it turns out, of keeping my spacing consistent. Then I selected all nine pictures and let Photomerge chew on the data for a while.
For those of you who've never tried it and are wondering how to do it, it's very easy in Elements 6: you just go to file —> new —> Photomerge panorama, then choose the pictures you want to put together, and it does its thing automatically. It takes a while, but it's not hard.
First of all, here's a small map of the individual frames and how Photomerge "jigsawed" them together. I can't make this bigger, but maybe it's big enough for you to see (the second illustration from the bottom of this post is the third one down here):
There were some anomalies. All I did to the merged image you see below was to crop it and straighten it slightly, but after the crop, a few mis-fits in the puzzle pieces showed up. Here's an example from the lower left-hand side of the image:
Oddly, these don't show up in the 100% version, but become quite prominent when I reduce the image size. I wonder if that's because I didn't flatten the layers in the .psd file first? (I'm not quite ready to do that yet.)
There are a couple of mis-stitches, too, for instance here:
...and some of them are relatively important, too (look at the tree and the telephone pole). I think I may have overlapped the frames too much. Here's a single shot to put you in context as to what my lens's angle of view is (it's about equivalent to a 50mm lens on a 35mm camera):
And finally, here's the raw result of the nine shots as put together by the Photomerge function. I think this is about equivalent to the angle of view of a 24mm-e lens, maybe as wide as a 21mm-e. (Click on the image to see it a little bigger.)
Mimicking a wider lens is probably not the software's strong point—it would probably be a lot better just to use a wider lens, which I didn't have on hand. Still, flaws and all, the software did a pretty creditable job, especially considering that I may not know how best to give it what it needs.
Photography really is as much about software as it is about hardware now. Photomerge at least goes a ways toward eliminating some of the limitations of shooting with a prime lens that's a little too long, which the DA 35mm Macro is for me. It makes it easy to change the aspect ratio of an image—you could fairly easily "shoot square" with a regular 3:2 ratio camera in many situations, for instance—and it gives you the option of a much wider angle of view than the native angle of the lens you're carrying, which could come in handy from time to time, as it did for me on Tuesday when trying to convey the scope of the flooded Fox River. It's not as good as a real panoramic camera because you have to have a certain stasis in your subject matter (you could have action in one or more frames, but not across the stitching boundary). Then again, with a little practice you wouldn't need a tripod, and some kinds of panoramic cameras—the scanning types like the Widelux—don't have instantaneous capture either.
I'm sure a lot of you reading this are a lot further up the learning curve with this than I am (this is all of my second attempt), just as, for some of you, it's all old news. And today's picture is a failed attempt, I think, all things considered (it doesn't really convey the looming quality of the tree at that corner, for one thing). But I'm impressed with the functionality. That I've never shot panoramas before has been mainly an issue of logistics: as a typical hobbyist I haven't wanted to deal with the expense of a separate panoramic camera or the burden of carrying it. But with neither of those penalties in play, that game has changed. I'm quite sure I'll be doing two- and three-frame panoramas in the future, at least occasionally, for subjects that warrant it.
Featured Comment by Ctein: "You can deal with most of the stitching glitches you're seeing by choosing 'interactive layout' in the photomerge control panel. Once the software has loaded all the images, it brings up a working window with the images arranged in the way it thinks is correct (similar to auto mode). Then you can drag them around and reposition them where you want. Photomerge will still snap them into alignment when you've got it close to correct, but you get to decide the starting point that is 'close' instead of the software doing it (erroneously).
"Note that the stitching errors are not addressed by rotating the camera about the nodal point nor using a special panoramic head. They are software glitches in the pattern analysis. Out in the real world I have not noticed any difference in quality from the precise manner in which the panoramic photos are made. The ones I showed of the Anchorage skyline in my 'stress tests' in previous columns were made hanging out a hotel window with the camera handheld; there wasn't anything close to trying maintaining proper body alignment.
"The analysis algorithms are extremely sophisticated and do sometimes make mistakes. For example, in the telephone line enlargement you showed, along with a mismatch there is what looks like a 'fold' in the sky like a sheet of paper had been creased. I saw that happen in my super-large panoramic in a completely blank part of the sky midway up off to the left side. Photomerge had stitched the images together perfectly automatically, so this was very strange. It looked like there was a crease in my monitor! Easy enough to retouch out in Photoshop, but I have no idea what caused it!
"I have also on occasion had Photomerge change its mind. One of my stress tests rendered correctly automatically the first two times I ran it. The third time I ran it the software put the individual images together in the wrong order. And thereafter it always put them together in the wrong order; I couldn't figure out how to convince it to automatically put them together correctly again (interactive layout solved that). Why it decided to do it differently on different occasions? I have no idea.
"This is why we really don't want artificial intelligence. A.I. gets notions!"
Featured Comment by Michael Bishop: "Here is my take on Photomerge; deconstruct it!"