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Tuesday, December 18, 2012

Extending Format

These techniques are for much more than panoramas

This Article Features Photo Zoom

In Photoshop, you'll encounter the Photomerge dialog. In most cases, you'll want to use all three options it offers—Blend Images Together, Vignette Removal and Geometric Distortion Correction—but any of them can be unchecked before producing the final merged file.

Photoshop offers five Layout
(or blending) options: Perspective, Cylindrical, Spherical, Collage and Reposition. The default Auto lets the software select the method it deems best for the images included. Perspective favors the center of the final image, allowing both horizontal and vertical distortion to become more extreme on the edges. Cylindrical favors maintaining horizontal alignment across all included frames, useful for keeping horizon lines straight. Spherical warps images in both horizontal and vertical directions. Collage repositions and rotates without distorting them. Reposition only repositions without rotation or distortion.

As a general rule of thumb, choose Perspective for images with an angle of view of less than 140 degrees, Cylindrical or Spherical for images with wider angles of view, and Collage or Reposition for scanned (moving the camera parallel to the subject) rather than panned (pivoting the camera around a central axis or nodal point) exposure sequences.

While Auto usually delivers good results, to choose an optimal final solution may require making a comparison between several methods. When evaluating the final results, in addition to determining how convincing the merge is, pay close attention to the relative distortions within the frame that each method creates. Variances in shape, proportion and line angle all can make a significant impact on an image.


Photoshop will place separate exposures on separate layers, transform and align and mask them, then selectively adjust color to create seamless transitions between them. It's magic! If you've ever done this by hand, you'll appreciate how much work is being done for you and how well it's done. Because the results are saved in a layer stack, you can fine-tune the results manually at anytime, now or in the future.