The first thing I did with Photoshop CS was use Photomerge to combine 11 images shot in two rows with five across the bottom row and four across the top. Photoshop CS had no problem automatically arranging all 11 of my images for a seamless merge. However, if you do encounter a situation where Photoshop can't place all the images automatically, you need only drop them close to where they belong, and Photoshop will snap them into place.
Once your images are arranged, the Photomerge dialog offers several tools to refine the composition. Along the left side there are tools to rotate, zoom, pan, and set the vanishing point. You can choose to have Photoshop perform a normal merge or apply perspective correction. When perspective correction is enabled, you can also choose to apply cylindrical mapping, which reduces the "bow-tie" effect often caused by perspective correction.
The advanced blending option makes transition areas as smooth as possible by blending across a wider area where there is less detail and across a smaller area where there is more detail.
As you adjust the settings, you can preview the results in the workspace. At any time you can save your progress as a Photomerge Composition File with a *.pmg extension. This way you can reopen the composition and work with it more from the point where you left off.
Once you're pleased with your composition, you will want to go ahead and let Photoshop create the merge. Expect it to take some time to process if you're merging more than a few very large images. The status bar will show you the progress.
Normally, Photoshop will combine, blend, and flatten the layers, leaving you with a completed panorama. If you prefer, you can check the "Keep as Layers" box to have Photoshop arrange the images into layers and let you perform the blending yourself. Unfortunately, you can't use "Advanced Blending" and "Keep as Layers" together. Generally, I prefer to let Photoshop do the blending. This sometimes leaves some uneven areas which may need to be corrected, but it is usually less work than doing all the blending manually.
For best results when shooting pictures for a Photomerge, follow these tips:
- Use a tripod, and ensure that it is level before shooting.
- If you can't use a tripod, lock your arms and legs and pivot your torso to capture all the shots.
- Line up the markings in your optical viewfinder with the horizon to help you keep your shots aligned when you don't have a tripod. (Tip submitted by Harald)
- Capture between 20 to 30 percent overlap between images.
- Avoid scenes with moving objects in them.
- Correct for any significant color and exposure differences in the shots before merging.
- If your camera offers a panorama shooting mode, then by all means, use it!