Creative Thinking in Photoshop: Stitching Seamless Panoramas without Photoshop
Recently I've become intrigued by the creative possibilities inherent in panoramic images. In my book Creative Thinking in Photoshop, I explained a procedure in which I created an image of the 20-foot south wall of my studio. In that case I manually stitched together in Photoshop a series of photos I had taken with a 35mm film camera with a 50mm lens (for minimal distortion) mounted on a tripod that I picked up and moved to the next location for each shot (see Figure 1). Though time-consuming, I ultimately got it to work by employing a lot of masks, adjustment layers, and hours of patching of problem areas in Photoshop (see my previous article "Problem Solving Using Layers" for some of the patching solutions I used).
Figure 1: My studio wall panorama: The seven photos shot with a 50mm lens (1a and 1b), that I then the manually "stitched" image created in Photoshop using layers, layer masks and adjustment layers (1c), and the final patched image (1d).
I wanted to see if there were easier ways to make panoramas, so I checked out recent articles on creativepro.com by Brian Lawler and Sean Wagstaff. These stories focused on virtual reality techniques -- notably with QuickTime VR -- and specialty equipment such as dedicated tripods that allow the camera to pivot around, and up and down, from a fixed axis.
But what if you want to stitch together photos that can't be shot in pivoted 360-degree swings from a fixed location? Or perhaps you want to shoot along a straight line (like a filmmaker's "dolly shot"), or around a corner to capture an architectural detail? You might find yourself home from vacation with a sequence of beauty shots you'd like to try and stitch together. Like most of you, I don't have the panoramic specialty equipment, or a "dolly rail" on which to hook up my camera. So when I've wanted to stitch together photos, I've historically used Photoshop.
Digital technology is forever changing, so I was curious if the new generation of consumer-level "automatic stitching" software would make such a painstaking process any easier. For this article, I looked at a few of the more popular options that generate a single, flat file from a sequence of images: Olympus's Camedia software designed to work in concert with Olympus digital cameras and proprietary memory cards; Canon's built-in stitching technology designed to work with its proprietary PhotoStitch software (part of Canon's Solution Disk); and a software package called Stitcher by a French company called RealViz. Lastly, although Photoshop hasn't added any automated stitching technology, its little brother Photoshop Elements has, so I included Photoshop Elements' Photomerge function in the tests as well. (Note: To download the Photoshop files that show the stitching comparisons in detail, see instructions near the end of the story and in the box to the left)
Equipment. To properly compare the results from each of the cameras and software options, I used three series of photographs:
- The same 35mm film shots of my studio that I had previously manually stitched together;
- A series of digital photos of a cityscape taken without a tripod on the Olympus C-730 digital camera with the Olympus xD media card;
- A series of digital photos of the same cityscape taken without a tripod on a Canon PowerShot 200 digital camera.
All sets of photos involved moving the camera along a plane parallel to the picture plane (a dolly shot). I then tried to stitch together each of these three series of photos together using:
- Photoshop Elements;
- RealViz Stitcher;
- Olympus Camedia Pro software;
- Canon PhotoStitch software.
For any of these software solutions, all sequences of images to be stitched must have the exact same resolution and pixel dimensions.
Process and Results: In order to achieve the best results, you must know the focal length with which your picture was shot -- that's easy to know with the studio shots that were taken with a 50mm lens. With the variable zooms on the two digital cameras, however, calculating the exact focal length of a shot can be complicated unless you are using the widest or shortest of the possible angles. Although focal length information is embedded in the file info, decoding how to translate digital focal lengths to standard 35mm can be a bit complicated. When you take your photo in the special Panorama mode in either the Olympus or Canon cameras, the focal length of the shot is automatically embedded in the image, and is therefore detected by its own software (and only its own software) to decode. That's why stitching the Olympus shots with Olympus software, or Canon shots with Canon software yield significantly better automatic results than possible with images from the competition's camera.
How well the software aligns single images into a seamless panorama is the most critical factor is gauging its success. Using high-tech panoramic gear that controls your pivoting from shot to shot makes it easier for you to align one shot exactly with the next, and therefore the images are more likely to fit together seamlessly. But when you're starting with low-tech, non-exacting photographic alignment methods, you're likely introducing situations that cause misalignment artifacts. When images can't be automatically aligned due to an artifact (such as a power line, or the edge of a painting), these stitching software programs deal with it in one of two ways: blur or soften the two versions together, or keep images crisper and allow for a margin of misalignment. Depending on your actual images, one might be a better solution than the other. For instance, vacation shots and soft landscapes would probably do better with the blurring which renders the artifacts less noticeable, while cleaning up misalignment might be easier and quicker for images such as the shots of my studio where I wanted a sharp image and knew I could clean up the artifacts in Photoshop).
If you're augmenting your existing professional panoramic photo studio, then the only one of these options that would make sense for you is Stitcher by RealViz ($499). Stitcher is built for the professional sewing together of images for a wide variety of different applications, from Web animations and QuickTime VR to low and high resolution flat beauty shots (see Figure 2). Stitcher can appeal to such a wide range of users by supplying a variety of different "projections" for rendering your image. Different projections include: Planar (rendering our "dolly" shots); Cubical (as if the panorama was projected onto a cube); Cylindrical (for QuickTime VR movies); Spherical (for those cool 360 degree images in games and on the web where you can see anywhere you look -- up, down, side to side, and anywhere in between) -- and more. This robust application does have a bit of a rough interface for Mac-o-files, though (for instance, the Zoom is a function, not a tool, making access quite awkward). I saw some impressive demonstrations using Stitcher (in concert with a professionally equipped panoramic studio) in which it not only created Virtual Reality images, but also removed artifacts, yielding fabulous results that didn't require hours of touchups. This was the only program that lets you to save a work session so you can return later, make any adjustments to your panorama, and then restitch
Figure 2: To order your images in Stitcher, drag thumbnails from the lower window to the upper window. You then align them, one on the next, before choosing to render. Only with Stitcher can you save your work session, so you can make further adjustments at another time. Though this is by far the most powerful of the programs, the use of tools will be the most foreign to those comfortable in Photoshop.
With power comes complication, however, and Stitcher is professional-caliber software designed to work with professional equipment. Stitching together hand-shot images using Stitcher's Flat modality (the "dolly shot" where you move the camera in parallel to the image being photographed) is not so simple when information is missing such as the exact focal length of the shots. It worked much better with the studio shots where I knew the focal length was 50mm, rather than guessing the focal length with the Olympus and Canon images (see Figure 3). Among the many, many parameters that Stitcher provides for controlling the stitching and rendering process are Defined Horizon, artifact removal, and "hot spots" for defining clickable links for Web or QuickTime VR movies.
Figure 3: With optimal equipment Stitcher yields quite high-end results (3a), but with low-tech equipment Stitcher images are decent when reduced, and a bit more problematic close-up (3b). Stitcher does less well with the Olympus (3c) and Canon (3d) shots in which the exact focal length is unknown.
The parameters within the Rendering export include a range of compression settings, "Smoothing" options (whether you will get more blurring or more misalignment), and two different "Mixing" methods that determine "the method Stitcher uses to blend the seams of stitched images." It is recommended you start with Method 1, and use Method 2 only if you're having problems with alignment. Method 2 won't fix the problems, but according to the manual, it "instead makes it easier to fix the image in an external graphics application. It is recommended that you do two renderings with each method, then composite the two renderings in an external graphics application" -- in other words, fix what's wrong in Photoshop.
Stitcher is the only one of these applications that lets you control how the software compensates for misalignment, whether the images are to be softer in which blurring hides the misalignment, or allow them to be misaligned. Even though I am convinced that it could do a better job if I had more time to learn the program, as long as you know the focal length of your shots, with a medium-length learning curve you can do a respectable job with Stitcher.
The software that ships with Olympus cameras supports a limited panorama feature with a series of narrow requirements: You must be using the Olympus xD card (not a generic SmartMedia card); you must be in one of the compatible program modes (such as Landscape); you must choose the Panorama setting; and then you must shoot in a left-to-right direction. To actually stitch the images together in the Camedia software you would then choose "Auto Panorama." The results of this automatic mode were pretty lousy for these hand-held shots, and it's not possible to load any photos shot under any other condition for stitching together, or manually reorder or replace any of the shots (for instance when I accidentally shot a series right to left). In fact this software has a pretty basic interface so I wouldn't recommend it as standalone software for $19.95.
On the other hand, upgrading to the CamediaPro software (also at $19.95) provides you with a good deal more flexibility, and better results, though still with a somewhat clunky interface (see Figure 4) --it's very slow to access your hard drive to find your files, for instance. If you aren't sure of the focal length you should still use the Panorama function with the xD card (which is also required for the next line of C series cameras) to shoot your images.
Figure 4: The Olympus CamediaPro navigation interface was the most awkward, paintfully slow. Once you have the correct folder of images chosen (on the left), drag one at a time into the work window and adjust alignment. Zooming tools and a scroll bar make adjustments simple.
With an upgrade to the Pro software you'll be able to stitch together sequences of images shot with any camera with quite good results, but you'll get the best results with Olympus's own coded pictures. The CamediaPro software tended to prefer clarity over alignment when stitching, which yielded the crispest, sharpest images of those tested, which also means that these were the shots with the most visible misalignment (see Figure 5}.
Figure 5: Using photographs taken with Olympus cameras and xD card, the Olympus software tends towards crisper images that allow for more misalignment (5a-5d).
Right out of the box, the easiest technology to use is the Canon system. When you choose the Panorama function in the PowerShot Digital Elph cameras, you can toggle the function so you can shoot left to right, or right to left. Then once you take the first shot, you'll see a preview that maintains the overlap of the previously shot image in the sequence so you can line up the next shot within the LCD (see Figure 6). This preview allows for decent alignment even with a handheld camera.
Figure 6: By far the easiest interface is the Canon software. When you launch it, you're asked to choose your images in the order you want them stitched and to specify focal length (if they're not Canon photos). Your images are then automatically stitched into the main window. You can make adjustments to the overlaps if you need to, but the automatic job is impressive.
The Canon Solution software package isn't very sophisticated, but the PhotoStitch component is by far the simplest of all the software to use, with the results being quite remarkably decent (see Figure 7). Especially when using photos taken with a Canon PowerShot camera, or with photo sequences in which you know the exact focal length of the shots (as in my 50mm studio shots), this software does first asks you to order the images, then it does an admirable job of seaming them together. The software comes free with your Canon PowerShot camera (it's $19.95 if you want to purchase separately for use with a non-Canon camera) and it provides a good middle-of-the-road balance between crispness and misalignment. When reduced these images are just fine to use as is, and will save you a lot of time over doing this manually.
Figure 7: The easiest system to use is the Canon camera with its software. The stitched images aren't quite as crisp as the Olympus ones, but as a result they hide the misalignments better in many circumstances, but worse in others (7a-d).
Adobe Photoshop Elements
Photoshop Elements 2.0 allows you to import any photos from any camera. The more accurate information you can give the software about focal length, the better your results. The main advantage to using Photoshop Elements over the Olympus or Canon software solutions, is that with Elements you get a full-fledged photo editing program. For anyone with a familiarity with Photoshop, the interface is a dream compared to the clunky interfaces of the other software. The Photomerge function looks very much like a Photoshop filter dialog box. (see Figure 8).
Figure 8: The Photomerge function in Photoshop Elements is really a dialog box. When you choose a series of images to stitch, it automatically orders them alphabetically, so in my case, some of the images had spaces before the numbers, so they didn't load in the correct order. Although you can manually rearrange, the job Photomerge does is respectable enough so you would do best to rename your files, and try again.
The Photoshop Elements' Photomerge function results in images that are crisp, with feathered blends between misalignments (see Figure 9). Unfortunately, these feathered blends create strange distortions that most likely will need fixing -- even if you reduce the image a lot. But fixing these images is made easier by the fact that with Photoshop Elements, at least you have built-in image-editing capabilities.
Figure 5: Photoshop Element's Photomerge function creates feathered but distinct transitions between misalignments in both the Canon (9a) and Olympus (9b) shots. The images will most likely need retouching (9c-d), but PhotoElements is the only of these software programs to provide retouching components within the application.
A Stitch in Time
All of these software solutions are much quicker and simpler than using Photoshop to manually combine the files. As with any project in the field of digital imaging, the major issue to consider before you adapt a solution is to evaluate what the final use of the image will be. If you have the high-tech equipment necessary to create micro-controlled panoramic shots, if you are creating Virtual Reality images, or even if you just intend to go through this more rudimentary process regularly, then Stitcher is likely your best solution.
If instead you are creating images for Web viewing (that will be reduced in size and resolution), or for personal use (so that great sunset can be in your album), there is little reason for you to look beyond one of these less expensive software-stitching solutions. If you stitch in high resolution and then reduce the size of the image, you aren't likely to see most of artifacts (see Figure 10).
Figure 10: The 50mm focal-length studio shots: Stitcher (10a), Olympus (10b), Canon (10c), Photoshop Elements (10d).
If you want a tourist camera with good support for panoramas, the Canon PowerShot camera series, with its onscreen Preview that helps with alignment, is a great choice, and the only all-in-one solution. If you have an Olympus camera and plan to stitch together shots, then do upgrade to the CamediaPro software. If you have another brand of camera and want some panoramic stitching support, then the inexpensive Photoshop Elements creates more unusable artifacts than the other options, and is a much more robust product than the Canon or Olympus software.
For the remainder of 2003, there are some huge promotions and rebates that bring the price of Photoshop Elements in line with the utility software offered by Canon and Olympus. The worst results of all came from stitching the Olympus images with the Canon software, and the Canon images with the Olympus software -- so if you own one camera, don't consider purchasing the other's software. If you have an Olympus or Canon product and software and Photoshop, then there's also little need for you to get Photoshop Elements. But if you have another brand of camera and want some help with stitching, or you don't have Photoshop and want an entry level version at a bargain basement price, then you can't beat getting Photoshop Elements -- at such a low price it's a great deal.
If you have another brand of camera and you already have Photoshop (sorry, but Photoshop, the big version, doesn't have Photomerge, at least not yet), you have the hardest decision. If you just want a little bit of stitching help, you should probably look at the Canon utility software (easier stitching), or Photoshop Elements (a little less automatic, but adds few extra features). If you think you want more help than this, consider how much stitching you want to do, and for what purpose. If you're intending to shoot frequent vacation shots, you should probably even consider purchasing one of the Canon PowerShot cameras, which start in the $200 range, and include the stitching utility. If you want to create higher-end panoramic images, consider purchasing Stitcher. And then of course, if you become truly addicted, you may need to purchase the professional gear suggested by Brain Lawler and Sean Wagstaff to help you take your pictures in optimal alignment.
As of yet, none of the software solutions generate layered files. That means if you're displeased with any elements within a flat, rendered, final file, retouching is a bit more difficult than in the manual way where layers are maintained, although RealViz's Stitcher does provide those two Mixing methods, which should aid in your retouching process. If you are creating high-resolution images for print, none of these software solutions will likely replace your having to manually stitch layers in Photoshop, but you can probably save a good chunk of time beginning with a software-stitched version, and then manually combining this stitched version with the originals source photos in Photoshop.
For a closer look at the comparisons, download the Photoshop files in which each stitching method is shown on its own layer.
- To download the Studio Wall panorama, Right-click or Control-click here.
- To download detailed images of the Studio Wall, Right-click or Control-click here.
- To download detailed images of the House shot, Right-click or Control-click here.
- To download the Cityscape panorama, Right-click or Control-click here.
Unstuff the .sit files, then open in them in Photoshop. Open the Layers palette, then view each layer one by one (hiding the other layers as you go along). You can see how well each application did in close-up. (Note: These are large files that will download under the name "jump" 1,2, etc. Uncompressing them will yield the complete file names.)
All Sewn Up
Finally, I wanted to give you some quick notes on the cameras. After trying them all out, I'm buying one of each. The Olympus C-730 is an amazing camera, with new improved models coming in the May/June timeframe. With a 10X optical zoom (38-380mm!), I was able to take pictures I hadn't thought possible. The Olympus C-730 is lightweight and discreet, a bit smaller than a standard SLR. Because the digital camera gave me instant feedback, I was able to make adjustments and keep shooting to get what I wanted instead of shooting rolls of experiments that didn't work (see Figure 11). Opening the aperture, speeding up the shutter, manually white balancing -- all are quite simple and give you immediate results. I haven't been so excited about any technology in a long, long time -- I love this camera, and can't wait to get the C-750 when it ships!
Figure 11: After accidentally discovering that I could capture the movement of jazz musician Kid Merv (at the Café Negril in New Orleans), I was able to adjust manual settings to control how the movement was recorded to the camera -- and shoot away! If I had waited for the film to come back, I would have missed this opportunity completely. To see more photos from this series, go to www.ssteuer.com/digitalphotos.
The Canon PowerShot camera is perfect for my husband. He's able to keep it in his pocket when he takes to the road with his remote audio recording. He's also a professional vacationer and always planning the next trip. We stopped lugging our SLRs years ago and instead got a good compact 35mm. Now I'll bring my Olympus, but even that camera is too big to always take along, so with the mini Powershot we're likely to reduce those times in every trip when we lament not having a camera. If you've been looking for a camera that's small enough so you always have it with you, this is it!
Read more by Sharon Steuer.
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