Lesson C: Panorama

Let’s construct a panoramic image. For this, we need appropriate source images. There are things that should be done when making the photos that will be combined like this.

Assemble Appropriately Captured Images

Each exposure should be the same so they can be blended together. This also implies that any adjustments done to an image after capture have to be done to all of the images in exactly the same way.

The images’ field of view should overlap by about 30% so the software can recognize elements to align them well. In a perfect world (this is not it, by the way), each image would be shot on a perfectly level tripod with the lens rotated around its nodal point between each exposure.

I used to do that. Then one day I ran onto a beach moments before the sun set and squeezed off five frames. They were made with the same exposure settings, handheld, as I pivoted my body from left-to-right in the sand, hoping I was overlapping the images by enough. Then the sun was gone. I assumed Photoshop would punish me for my haste and laziness. I was very wrong!

Again, we’ll compare ACR’s merge with Photoshop’s. They are similar but not the same. If you’re displeased with one for your own work, by all means try the other.

• In Bridge, select the five images whose name begins with “Panorama.” To try ACR’s method first, use the shortcut ⌘-R/Ctrl-R to open the images in ACR.
• Use the shortcut ⌘-A/Ctrl-A to select all the images in the Film Strip panel.
• Right-click on one, then choose Merge to Panorama…. A dialog box opens with ACR’s initial offering.

Because I didn’t use a level tripod and pivot around the lens’s nodal point, the software warped each image to overlap and blend them like they’re pasted inside a cylinder.

ACR figures out just how to cut each image to blend them nicely. Photoshop does that too. Since I panned around nearly 180º with a wide but not very wide lens, the choice of Cylindrical Projection (in the dialog box) is ideal. If there had been any sailboats in the shot, their masts would be nicely vertical in this projection too.

If I was using a fish-eye lens, Spherical would be more appropriate, as the images could be mapped to the inside of a sphere that way. But masts would bend oddly in that projection. If my shots covered less of an angle, and my subject had lots of straight lines like a building might, then I’d try Perspective Projection.

At the bottom, in the Image Workflow section, ACR is making an undesirable adjustment with its Apply Auto Settings. Sometimes it helps, but not this time.

• Disable Apply Auto Settings.

Now we have three ways to deal with the bulbous image boundaries.

• Try Auto Crop. Toggle it on then off so we can compare it to the other options. A lot gets chopped off. Uh-oh.

• Drag the Boundary Warp slider. Now that is interesting. But the horizon bows a bit. Still, we’ll keep this in mind! Set Boundary Warp back to 0.

• Enable Fill Edges. This uses an algorithm like Photoshop’s Content-Aware Fill. Content is taken from elsewhere in the image to plausibly fill in those voids. That is pretty awesome!

Photoshop’s Photomerge feature, used mostly to make panoramas, also results in an image with bulbous bounds unless we tell it to do something much like the Fill Edges trick above.

• Clicking Merge… generates a new DNG that you can choose to edit in ACR.

You’ll see it added to the Filmstrip panel. Like with the HDR DNG, you can click Save Image… to create a deliverable, or Open Object to pass the pano to Photoshop for something fancy.

• Click Done and plan to return to that DNG later. Back to Bridge!
• With those original five images highlighted (they likely remained so), choose Tools > Photoshop > Photomerge….

Note that the images listed in the Photomerge dialog box are the ones you chose. Here, the projections are called Layout and there are two other choices: Collage (which rotates and scales to fit the pieces together, but won’t make things bulbous) and Reposition (which will not transform the parts at all but will reposition them).

At the bottom of the dialog are checkboxes. Blend Images Together creates layer masks on the layers created for each image to stitch them together smoothly. Vignette Removal and Geometric Distortion Correction are there if we forgot to use those Lens Profile Corrections in ACR—but we didn’t forget. Finally, Content Aware Fill Transparent Areas is the verbose equivalent of ACR’s Fill Edges. We need only the first and last, and they’re checked already. Auto Layout will be cylindrical because Photoshop is that smart. All you need to do is…

• Click OK and wait. If you don’t like the way the edges were filled, remove the top layer! This is a rare time when I’d choose Layer > Flatten Image and then save the result.