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For lesson one, you're going to want a copy of V Borodinskom muzeie. Borodino (In the Borodino Museum. Borodino) where we can see some fine artifacts of the Battle of Borodino. I have no idea whether these artifacts are still in existence; the photograph was first published in 1911, which would have made them 99 years old at the time. So it'll be nice to vicariously see back almost 200 years into the past. Download the large archival tiff with all three exposures; it has a filename of 00403u.tif and is approximately seventy megabytes in size. Don't open it in the browser, download it to your hard drive. (Apologies in advance to those of you on dialup.)
I chose this image, in part, because it gives a splendid demonstration of exactly what we're dealing with here, which is three grayscale images all of the same subject, recorded simultaneously through a red, a green, and a blue filter (think theatrical lighting gels). For example, simply by eyeballing the differences in shading between the three, it becomes evident from the lightness in the bottom image, coupled with the darkness in the other two, that the matting in the display case is a bright red. It's not yet clear what color the upholstery of the bench is, but it's fairly obvious that it's not a bright blue. I also chose it for the beginning lesson because it's remarkably free of blemishes, which will be the subject of later tutorials.
Perhaps one of the reasons for Prokudin-Gorskii's rediscovery in the present time period is the fact that it is now possible, with computers, to make these into marvelous color depictions that were impossible with the technology of Prokudin-Gorskii's day (printing the images, for example, was out of the question). This might, additionally, be an indication of the man's being born well ahead of his time.
Open this up in Photoshop. It takes a while, even on my machine (which is no slouch). We'll do various manipulations along the way that will have the effect of speeding things up.
Unfortunately, due to an apparent oversight by Photoshop's programmers (perhaps it's being saved for a later release?) the program allows for only the most rudimentary manipulation of sixteen-bit grayscale images, precluding even so much as the use of the "copy" command, which is what we want to do next. Therefore it will be necessary to go under the Image>Mode menu and select "8 bits/channel". The result looks virtually the same to the naked eye, although of course there is a loss of color detail. Nevertheless, given the enormous size of the LOC's archive files it will be quite sufficient for a 300dpi output of, say, 8½×11" (probably not a poster though).
(I might add that I suspect The GIMP will handle such monster files, and if so I would encourage users of that program to write a similar tutorial. Support free software.)
Now if you're a packrat, like me, you'll do a "save as" at this point, but if you're not an obsessive-compulsive who thinks all the scattered CDs on his desk somehow put him on a par with the Library of Congress, you can just do a save, thereby saving space on your hard drive.
Now we're going to make a selection, and for this I don't use such fine detail, either, these files open at 8.33% magnification on my monitor and I just leave it there for now. However I do a bit of tweaking in the process.
Try to eyeball the largest of the three images (you thought they were all the same size, didn't you?). The middle one (green) is usually biggest, but try all three before copying, and use Select>Transform Selection to get it to the size of the largest one. Don't be afraid to pull some of the edges around the image along with the selection (in other words, "too big" is preferable to "too small"). Once you have the selection sized on the largest frame, you can just drag it around to copy the other frames (try to center it but there's no need for absolute precision). That way they'll all be the same size when it comes time to paste them.
Now it doesn't really matter what order you copy the selections in, I usually just start with the largest first. After you copy the first one you're going to want to make a new image, select Mode-RGB Color in the dialog box. In the Channels floating window (bring it up from the Windows menu if you don't yet have it) all three color channels will be selected by default, so click on the one you're working with to make it active. You'll paste the center selection in the Green channel, the top one in the Blue channel, and the bottom one in the Red channel. (If you've only got one channel, grayscale, you haven't got an RGB document; go into the Image>Mode menu and select RGB Color before continuing.)