Presented October 9, 2010

Panoramas

One of the most powerful tools in Photoshop is also one of the easiest to use. The Panorama tool, which is found in the unlikely location: File > Automate > Photomerge... requires very little input; it simply knows how to stitch sequential panoramic photos together seamlessly. Our job is to provide the raw photographic material.

Photographing a Panoramic Sequence

Ideally, a tripod with a panoramic head that allows the camera to rotate around a fixed viewpoint in consistent angle increments is used. The next best approach is to employ a tripod head with a 360° scale that can be manually rotated in consistent increments. But most likely, you will find yourself out and about in beautiful surroundings, suddenly taken by the urge to “get it all” with whatever you have handy. The good news is that Photoshop is incredibly forgiving when it comes to stitching your panoramic sequences together. Believe it or not, handheld images can work very well.

For best results, always shoot panoramas in portrait format rather than landscape. More photos are required this way, but if you imagine that you are photographing arcs of a circle, the smaller the arc represented by each photo, the better your circle of images will be rendered. If you have the panoramic tripod head, rotate the camera 15° for each image. This will allow for the proper amount of overlap between each image: Photoshop needs enough overlapping information between two images in order to properly match them up. Be careful though, too much overlap will confuse the program and it will be unable to string your images together. If you are handholding the camera, try to get 40% overlap.

Processing

For this tutorial, I will use four images of the Santa Cruz Boardwalk taken from the Santa Cruz wharf. The photos were taken with a cell phone camera; only worth noting because these cameras are only marginally accurate for this purpose, yet Photoshop will produce a reasonable panorama from them. Also note the overlap is less than ideal and the color balance varies significantly from photo to photo.

As mentioned earlier, using the panorama function is simple: File > Automate > Photomerge.... The Photomerge control panel will open up, presenting: 1. alternate approaches to rendering the panorama in the Layout area; 2. source image selection and 3. rendering refinements in the Source Files area.

Photo Selection

There are two options for selecting photos for the Photomerge tool within Photoshop: 1. Click Add Open Files to select all open images. This assumes that only the sequenced images are currently open and have been saved in their current format. If you have edited an image, it must be saved for Photomerge to include it in the panorama, but not to worry, Photomerge will warn you if an open image is in an unsaved state. 2. Click Browse to retrieve image files from your computer. Additionally, if you use Bridge, you can highlight the desired images within Bridge and select Photomerge: Tools > Photoshop > Photomerge.

Layout

• There are several layout rendering options, but the simplest method is to select Auto which will determine the best rendering technique for you. That said, there are a few layout choices worth a brief description:
• The Perspective option will select a central image from the photo sequence as the focal point and work outwards in each direction matching the remaining photos and stretching as necessary. This tends to create a stronger sense of perspective with a resulting bow-tie shaped rendering reminiscent of a single vanishing point perspective drawing.
• The Cylindrical option attempts to map your rendering around a cylinder and then flatten into a 2-dimensional image. This technique reduces the bow-tie effect.
• The Spherical option maps your image to the inside of a sphere. This technique is ideal for full 360° panoramas. For more information see Adobe TV’s Enhanced Panoramic Photomerge video presentation.

Refinements

• Blend Images Together is selected by default. Because Photomerge does a superior job of blending and matching color, it is generally best to leave it checked.
• Vignette Removal is useful when the edges of your photos are darkened or washed out. Photomerge attempts to minimize this distracting detail that weakens the impact of a panorama.
• Geometric Distortion Correction corrects bowing and pincushioning caused by extreme wide-angle and fish-eye lenses.

Finishing

Once you've selected your settings, click OK and Photomerge takes over. The application will collect each image on a separate layer, position each, blend the images to match and merge the result into the top layer. This is a memory intensive process. If your RAM is less than robust, be sure to provide substantial scratch disk space: Preferences > Performance... > Scratch Disks. Even with lots of RAM you may have to wait a while for panoramas built from larger image files and/or more of them.

Usually, the image can be flattened since the build layers have little value on their own. Crop your image and you’re done!