2.5. Stage 5

2.5.1. The assembly

Before launching ImageAssembler I made sure that the pictures were all the same size in pixels. Their format wasn't important since the program can assemble pictures in JPEG, TIFF, BMP, PICT, and other formats at the same time.

In ImageAssembler, images are assembled in two stages. First you launch the Lens Wizard, which needs at least two contiguous pictures from the panorama so it can calculate the parameters of the shot: camera angle, focal length, optical distortion, etc. Open a blank stitching project and pull the pictures into it, place a series of flags at the same places in two adjacent photos, and run a trial stitch by clicking a button on the toolbar. ImageAssembler calculates the parameters; you'll save these parameters and use them later when you stitch all the pictures together.

I opened the five pictures of the series and arranged them in order from left to right, including the two photos that I had earlier corrected in Photoshop. You can place the flags automatically or manually. I've had great success in placing them by hand, so I took the manual route. I then selected the Lens Wizard parameter file that had just been calculated, chose the projection type (in this case, spherical), and started the stitch.

In the completed assembly, the perspective was corrected: the straight vertical lines no longer converged. ImageAssembler's sophisticated algorithms do this by subtly warping the pictures, as if they'd been projected onto a sphere. Save the image in the desired format (JPEG, TIFF, and soon, PSD).

Note that the rotation axis of the camera was apparently perfectly horizontal, since the assembled photographs aren't tilted to one side.

For landscape photographs with areas of sky, I chose an Image Blending value of 50–60% in ImageAssembler and unchecked the Adjust Colors option.

2.5.2. Retouching

Final retouching is made easier if your monitor is correctly calibrated and Photoshop is set for proper color management (Edit → Color Settings).

If the pictures were properly shot to begin with, most of your retouching work is done. But check for any assembly artifacts that may have appeared in the overlap area. You'll need to use Photoshop's Clone Stamp tool to gradually eliminate these artifacts the old-fashioned way. Future versions of ImageAssembler will let you paint directly on the layer masks linked to each photograph since the resulting assembled image can be saved in Photoshop's PSD format, maintaining all the layers you've created.

All that's left to do now is to trim the uneven edges of the photograph with Photoshop's Crop tool.

To finish, I used the adjustment layer to check the various levels of the final image—brightness, color balance, and such—as I would for any photograph.

The layer masks associated with adjustment layers can be very handy when you only need to make corrections to a specific area.

It's hard to tell from the resulting panorama that it was created by assembly, or shot with modest means and fairly quickly.