STITCHING for a WIDER VIEW
(This article originally ran in the May, 2013 Camera Bag column in Railfan & Railroad Magazine.
It has been updated for presentation here.)


As described in the text, stitching together the two adjacent images below was necessary to achieve the desired wider composition to include the block signal in this photo of UP and BNSF trains together on Colorado's Joint Line.

First, this photo was taken to include the block signal
as the UP train approached. Note how all of the BNSF locomotive could not fit in the composition.

Next, the main photo was taken when the UP train
was passing the BNSF locomotive on the spur track. After combining the two images below in Photoshop, the more effective wider composition above was achieved.
With digital (as well as scanned film) by using a computer image program to combine two or more photos, it is easy to "extend" your composition when you need a wider angle lens to get the image you want. Such was the case when I set up to photograph a southbound Union Pacific train passing a Burlington Northern Santa Fe locomotive on the Spruce spur a little north of Palmer Lake, Colorado on the BNSF / UP Joint Line.

The Joint Line grew out of the original 1871 narrow gauge Denver & Rio Grande "Baby Railroad" (for the 30 pound rails and small locomotives and cars) of Civil War General William Jackson Palmer, building south from Denver, Colorado to a connection with a Mexican railroad at the Rio Grande River in Texas. The D&RG never reached Mexico, but this line led to the formation of the 120 mile long double tracked high traffic route between Denver and Pueblo we know today as the Joint Line.

The Joint Line came about when the Atchison, Topeka and Santa Fe completed their line between Denver and Pueblo in 1887, paralleling the D&RG line. The two railroads operated as separate, competing lines until WW I when the United States Railroad Administration took over control of the nation's railroads for the war effort, and mandated all Denver-Pueblo rail traffic would be a joint operation sharing the ATSF and D&RG lines. In addition, Colorado & Southern, Missouri Pacific, and Rock Island at one time operated over the Joint Line.

Today, all these railroads have funneled down to the two present Joint Line owners. Rio Grande morphed itself into the Southern Pacific in 1988, which in turn in 1996 was sold to UP. The BNSF is the result of the BN absorbing the Colorado & Southern in 1981, then merging with the AT&SF in 1996.

Since this spur track is normally empty, I saw this BNSF locomotive alongside a UP train as a rare opportunity to illustrate in one photo the multi-railroad history associated with this line. I also wanted to emphasize (with mild telephoto compression) the pattern of multiple rails, so selected my 180mm lens.

I liked the idea of including the block signal, but it was just outside the framing of the 180mm lens. I could not back up more to include this signal without having a switch stand intrude into the view I wanted of the multiple rails. And while a smaller tele would be perfect for the shot, the next smaller lens I had with me, a 50mm, would loose the telephoto compression effect I wanted on the rails.

So as the UP train was approaching, I shifted my composition very slightly to the right, took a shot including the block signal (while cutting off part of the BNSF locomotive on the left), then recomposed and took my main shot when the UP locomotive was alongside the BNSF. Later, I combined both in PhotoShop. I cropped out about 70% of the left side of the block signal shot, then added the remaining image to the right side of my main shot. While this can be done automatically in a stitching program, I did it "manually" using the following stitching process. (These steps are for Photoshop, but should be the same or similar in other image editing programs.)

1) I opened both images, and sized them both to the same height and DPI as my final image. Next, I opened a blank canvas (FILE MENU > NEW) at the same DPI and set an image size larger by 2-3 inches on all edges than the intended final print size (to allow room to work on the images.) I then dragged the two images onto the blank canvas, placing the image with the block signal over the main photo, lining up the "35 sign" in the top image over the same sign in the bottom. Each image now became a layer. Next, I cropped off all of the top image to the left of the 35 sign, leaving only the right 1/3rd of the image that included the block signal.

2) I set the opacity of the top image layer to around 50% (in the Layers box, use the Opacity slider) to allow me to "see through" the top image to compare and match up details with the bottom image. Using the zoom-in tool to enlarge the image for easier detailing, I used the perspective, scaling and distortion controls under EDIT MENU > TRANSFORM to adjust the edges of the top image layer so all details lined up exactly with the bottom image.

3) Once everything matched, I reset the opacity of the top layer (the added photo) back to 100% and used IMAGE MENU > ADJUSTMENTS > LEVELS (CURVES can also be used) on each layer as needed to match up slight differences in tonal values. I flattened the layers (LAYER MENU > FLATTEN IMAGE) and cropped to clean up any uneven edges.

When taking two or more photos like this to join together, ensure you keep everything level when swinging the camera to line up a new composition. And set focus and exposure manually so they remain the same with each composition. Autofocus and autoexposure may change slightly as you swivel to take the overlapping images.

Stitching Big Boy
The image of Union Pacific "Big Boy" 4005 at the Forney Museum of Transportation in Denver was achieved in a similar manner. I wanted a clear photo of this largest of all steam locomotives, but there was not enough space in the interior of the museum to capture the entire locomotive with one photo even when using my widest lens, the 17mm end of a 17-55mm zoom on a Nikon D200.

I took several photos moving the camera around to capture all aspects of the subject, including the ground around the front of the engine. I combined the best two of these images using the multiple stitching steps covered above, selectively burned in the dark background to obscure the building interior, and did some judicious cloning to fill in missing parts of the floor in the bottom foreground. Finally, I converted the image to black & white so as to better blend in with the darkened background.


Union Pacific Big Boy 4005 in the Forney Museum of Transportation in Denver is displayed in a location too tight to get a full photo even with a 17mm lens on a D200.

This additional image was taken to include the front of the locomotive.


The final image after merging the first two, darkening the background, then converting to B&W. The end result is not as dramatic as a photo of a Big Boy in operation, but is as nice as possible under the circumstances.

Back to Top     Back to the Index Page