Photo-stitching takes two or more photographs, and merges them into a single larger picture.
What's Photo Stitching Good For?
Photo stitching is useful for creating:
* Landscape photographs. The 4:3 aspect ratio of standard digital photos does not give justice to vistas, such as of mountain ranges and towers. Take 3x1 (or more) photos.
* Wide-angle photographs. Most digital cameras have a wide-angle setting, but in some cases you cannot step back far enough to capture the entire scene. Take 2x1 or 2x2 photos.
* High-resolution photographs. Photo stitching creates photographs with many times more pixels than the 3.1 megapixels the S1iS is limited to. This allows you to make larger prints that look clearer. Take 1x2 or 2x2 photos.
* 360-degree QuickTime movies. Take enough photos to go all the way around, typically 18, I find.
Sometimes Stitching Works Poorly
Photo stiching does not work in some cases. Here are problems I've come across (tips to solving the problems come later).
* The scene is not perfectly horizontal or vertical. When the photos are later stitched, they end up curving. In a few cases, the effect is quite nice; most times it is annoying. I once took 360 degrees worth of photos from the inside of a dormant Auckland volcano; the stitched result is in an S-shape!
* Stuff changes in the scene -- moving people, cars, waves, tall grass, and so on. Where the overlap occurs between two photos, people and cars look distorted. I used photo stitching to capture my son's entire Grade 12 grad class; at the seams, one girl has three arms, and a boy has two faces. The Photo Stich software has difficulty when the overlap of two photos doesn't match well, such as in photos of moving waves and waving fields of grain.
* Changing lighting conditions. The camera keeps the same exposure settings for all photos in a stitch series. If the sun is coming in and out of clouds, one photo will be just right, the next too dark or too bright -- the overall effect just doesn't work.
* It's tough to line-up the overlapping images in the S1iS's under-sized viewfinder. Other times, you lose track of where the overlap should occur, because there isn't anything distinctive with which to line up the views.
* Stitch photos don't work when you are too close to the subject, whether of a person or inside a building. That's because the field of view changes too much between photos. I've tried stitch photos of the insides of churches, and it just doesn't work well. Stitch photos work best of scenes where the item of interest is far away.
Photo Stitching Tips
For vertical and horizontal strip photos, the camera must be perfectly horizontal (or vertical). If not, then the images gets rounded edges or even goes in waves. (Click photo at left for larger iamge.)
To ensure the camera is level, I could pay $40 for a bubble level that fits the camera's hotshoe (which the S1iS lacks). Instead, I went to the local lumbar store and got a small bubble level for $4.
The bubble level can be a pain to position on top of the camera, especially on ones that don't have flat tops, like the S1iS. Still, you have to use something to set the camera upon; avoid taking stitch photos holding the camera just with your hands.
Use a tripod or a park bench or the edge of a tree or the top of your car. To ensure the camera is roughly level, I scan the scene: pan (move) the camera from one end of the scene to the other, checking that things roughly line-up from end to end.
When stitch-photographing a mountain range or a cityscape, I am usually not interested in the vast expanse of sky above. For this reason, I often zoom in and rotate the camera to vertical. This maximizes the resolution of the scene and minimizes the unwanted areas above and below the scene.
Another times to use vertical orientation: when you want to create a high-pixel-count image, take two or three vertical photos, then stitch them together.
And avoid Over-Stitch-Itis: that's the problem where I end up taking 12 photos of a scene. That many strung together become unwieldy for viewing and printing. That's because such a wide photograph views and print very narrow in the vertical direction -- 12 inches wide and 2 inches tall.
Can you overcome the 2x2 limit? Yes, by taking a horizontal photos, and then another strip just below. The Photo Stitch software will stitch together any photos, as long as there is the correct number. For two rows of photos, there must be the same number in each row. If you take 3 photos (of the top of a mountain) and then take 5 photos below, Photo Stitch won't merge them; it needs to be 5 and 5.
Printing Stitch Photos
A real pain. It's not easy. After days, weeks of puzzling over the problem, I finally found a solution. I use the HP PhotoSmart P1100 printer (excellent printer, I might add, now that the printer driver works properly -- used to refuse to print in landscape mode! I much prefer the HP over the Epson I used to use, because the ink never dries out, a constant problem for Epson inkjet printers.)
I noticed that the printer could handle banner paper, because of an icon on the printer's paper tray, which indicated that one part of the tray needed to be lifted up. But there isn't a single word on banner printing in the printer's documentation or at the HP Web site!
Photo Stitch comes with an ancillery program for viewing and printing stitched photos, called Viewer.exe. Open a stiched JPG file, and then click Print. A dialog box appears:
* Turn on - Print Over Multiple Pages
* Turn off - Print With Overlaps
Scroll the preview image to see how the image fits the paper. Usually, I want to maximize the image. To do that:
1. Click Cancel to exit the dialog box.
2. From the File menu, select Option.
3. In the Option dialog box, enter a different value for dpi. The default is 240.
* A larger value,such as 300, makes the image smaller.
* A smaller value, such as 180, makes the image larger.
It's now a frustrating cycle of changing the dpi value, and then going back to the Print dialog to preview how the image fits the paper.
When satisfied, insert the banner paper in the printer, and print.
Canon Stitch Modes
Some Canon cameras have a shooting mode that assists you in taking overlapping photos. Later, when you can get the JPGs to a computer, you run the Photo Stitch software to merge the images into a single photograph.
There are three ways to take stitchable photographs:
* Up to 26 photos vertically (up down,or down up) -- good for landscapes and 360-degree movies.
* Up to 26 photos horizontally (left to right, or right to left) -- good for photos of tall towers.
* Four photos in a 2x2 array -- good for extra-wide-angle shots and 8-megapixel resolution images.
The viewfinder shows the previous photo so that you can align the next photo with an overlap of about 1/3. The overlap is necessary so that the Photo Stitch software can automatically merge adjoining photos.
Why the limit of 26 merged photos? It is due to the file naming convention Canon uses for stitchable photos: STA_2360.JPG, STB_2361.JPG, and so on, through to STZ_2386.JPG. "ST" is short for "STitch" and the "A" designates the first photo in the stitch series.
Note that Canon changes the JPG quality to superfine. If you normally use JPG Normal quality (as I do), you may suddenly find the camera reporting that your memory card is nearly full!
Photo Stitching Software
The S1iS comes with Photo Stitch software on the accompanying CD. It's pretty good; other software is available, but costs $$$.
There are some features in the software that help you with difficult merges. Check out:
* Crop photos with curvey and uneven edges to create a rectangular images. (Click photo at left for larger image; the green rectangle indicates the crop outline.)
* Manaul merging (pick two points on the two adjacent photos) - click the Display Seams button, and then click a seam.
* Change the merge style - Merge Settings, and then select Parallel Camera Movement, and see if that makes the image better.
* Switch between normal and wide angle - click Adjust Image button, and then select wide. This sometimes helps buildings look square, but makes landscapes look worse.
* Create QuickTime movies - click Arrange button and select 360 Degrees; save in QuickTime format.
For the ultimate photo-stitch image, check out Breaking the Gigapixel Barrier -- 196 photos of the Grand Canyon stitched together to create a 1-gigapixel (billion) image.