First off, the software that is use, why i use it and some alternatives.
http://people.cs.ubc.ca/~mbrown/autostitch/autostitch.html ) which is also free and does a good job, it actually seems to do slightly better blending between images(you may get some hard transitions with ICE that you will need to paint out/clone stamp out) BUT, ICE gives you some great interactive tools, you can change the projection/distortion types, and some tools to give you a bit of control over how and where the image distorts. It is also multi-threaded, which means that on my quad core CPU i can render out the highest resolution composites in about the same time Autostitch takes to render a 25% image.
http://www.gimp.org/ ) are free, quality tools that should be able to do most of the same stuff i do to photos in photoshop. Paint shop pro is also a good tool that can be had for about $30 on ebay if you buy a slightly older copy, my fiance and her father use paint shop for all of their scanning/photo work with the ebay business they run together, and i've used it in the past and would recommend it as a great photoshop alternative on a budget.
Now, onto the actual guts of the process.
First off, a few things to consider when taking the photos
1. For panoramas, a tripod can be very useful to get a steady shot and keep the camera even the entire time. I often just wing it and shoot without one however, but if i took a little more time and used my tripod i think i could get a bit better quality.
2. I like to use the continuous mode on my camera, the important thing here is when i do that, the exposures will stay the same for each image in the series as i take them. If you take them one by one, the exposure will tend to vary, the stitching program should be able to account for this, but you may get some strange results in doing so(some areas being a littler brighter or darker etc).
3. If you have a good manual mode on the camera i would use it. Experiment with things like turning off flash, adjusting the exposure levels manually so that the brightest parts of photos aren't over blown, and using the "infinite" focus mode for doing far away panoramas like sunsets and things like that. I actually got my camera because it has really good manual settings for a point&shoot.
4. With the manual mode on my camera, even when i set the exposure manually, my camera still does sort of an "auto" exposure based on how bright/dark the initial source is, so that is something to keep in mind, the manual setting on my camera just seems to tweak the auto setting from -3 to +3 depending on where i set it. After a little experimentation here it should be easier to decide where to set it.
5. You can choose to take these shots either wide or tall, i like to do tall as i feel it gives me more resolution, you just need to take more horizontal shots this way, i like to have really high res source material to work from, in case any of it is out of focus a bit, so you can size and down, sharpen, and hopefully not notice. Depending on your camera and the software you use to stitch, you may have to manually rotate each image so that it is upright.
Ok, so now that we've taken our photos, we should have something that looks like this:
This is a shot from Adobe Bridge(comes with photoshop) i like it for keeping track of large groups of images. So here you see all of the different shots, you can see that there is plenty of overlap between image so that it will be easy for the program to stitch it all back together.
Now that we have all of our images, we can open ICE and go file->new and drag-select all of the images in the series. You should see a progress bar here, which may take anywhere from a couple minutes to maybe a half hour or more, depending on how large each image is, how faster your PC is, etc.
Here you see it all stitched together for the first time. For this one i don't really need to do much tweaking, so the only things i need to pay attention to are the cropping, and the size it exports at. I'm going to crop in photoshop so i don't need to worry about that here, but its easy to do your crop at this time. The important thing that can be easy to forget, is it usually defaults to 25% or 33% for the scale, but i want the full res 10198x3948 image to play with when i export, so i always have to remember to set it to 100%. Its worth noting that if you don't have a computer with a fast CPU, lots of ram and a good video card, editing very large images is going to be very painful/may crash/freeze your system, I've got a graphics workstation here however so i always want the highest possible resolution.
Now, we don't need to make any adjustments here, but if we did, you can click on the cube icon on the top row, and it will give you all sorts of options to play with.
You can see by dragging the image around a bit, and changing the projection type we can create various effects. These above shots aren't actually something you would want to do, just an example on how the tools work, i generally just do some minor adjustments when needed, and usually either Cylinder(horizontal) or Sphere(horizontal) are the only projection methods i use. Generally the automatic setting is pretty good.
So now that is all done, all we have to do is export. I generally like to use TIFF as it is uncompressed, but full resolution tiff files can be very large, so you may want to consider JPEG or PNG if that is an issue.
Alright, we've got our panorama stitched and exported, its time to load it up in photoshop/your tool of choice. I've made an animated GIF here that shows the processing i do to most any photo after i get either straight from the camera or a stitch like this.
1. Load image
2. Rotate(if necessary)
3. Select crop region
4. Crop
5. Adjust Curves, you can get similar results with levels, but i prefer the flexibility of the curves tool. There should be similar tools in most apps. What I'm doing here is A. bringing out the darks a little more(as you can see the far left of the histogram there isn't any detail there) B. Adding contrast and brightness by pulling up the 2 right points there.
6. I scale down to resolution i plan on using for the final image, in this case 2500x****
7. I run unsharp mask with a low amount and a high radius to bring out some contrast in the larger forms
8. I run unsharp mask with a higher amount, and a much lower radius to sharpen up the individual pixels(this is closer to a standard sharpen)
9. Final image!
You may also need to do some cleanup if there are any noticeable errors for the stitch, either by painting them out or using clone stamping or something. If i don't notice these on first glace i usually don't worry about them.
There you go, if anyone has any questions about any of the steps, why i do something, etc feel free to ask i will try to respond. Its actually a lot more simple than it looks here, i just tried to go as in-depth as i could to explain exactly what i do. Sorry about the huge GIF image, it may take a while to load for some people. 🙂