Tuesday, February 12, 2013
How To Go Big
Get more resolution from your camera with these three key techniques: Upsample, Stack, Stitch
|This Article Features Photo Zoom|
Another method for increasing the resolution of your image files is to break a scene into pieces with separate multiple exposures and then stitch them together using panoramic merge functions in today's software. It's a matter of simple addition—two files are better than one, three files are better than two, etc. With this method, detail is optically captured, though you also can choose to enhance it further with software. While you can consider dedicated panoramic software like Kolor Autopano Pro or PTgui for challenging images, it's highly likely that Photoshop is all you'll need.
Take these steps. In Bridge, select the files you wish to include in a photomerge and go to Tools > Photoshop > Photomerge. Alternately, in Lightroom, go to Photo > Edit In > Merge To Panorama In Photoshop. Either way, you'll end up in Photoshop and 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 will place separate exposures on separate layers, transform and align and mask them, then selectively adjust color to create seamless transitions between them.
When you make exposures for stitches, shoot a little loose, as it's quite likely that the border of the final image produced will need to be cropped (or cloned) to be made rectangular. You also may encounter some spatial distortions in stitched images, either subtle or dramatic, depending on your exposure methods. These can be corrected, in part or in whole, after a merge with Photoshop's powerful distortion tools: Free Transform, Puppet Warp and the filters Lens Correction, Adaptive Wide Angle and Liquify.
Moving objects can present challenges for stitches, and Photoshop will allow you to select their position based on a specific frame and automatically remove ghosts, but artifacts in fields of motion, such as water or clouds or foliage, are often inevitable, making this technique suitable for many, but not all, situations.
How far can you go? The lens is the limit. Theoretically, you can stitch an infinite number of images. The true limits lie in how much your lenses will allow you to zoom into a scene. Yet, the most important factor still remains: What's practical in a given situation? Other questions arise. What's better? Fewer exposures made with a higher-quality lens? Or, more exposures made with a lower-quality lens? The answer lies in how much the quality of one lens exceeds another. Compare manufacturers' MTF charts (they're readily available online) for useful objective data that will shed light on this.
So, when you want sharper, bigger digital images from your existing cameras, you have options. Remember, upsample, stack and stitch.
John Paul Caponigro, author of Adobe Photoshop Master Class and the DVD series R/Evolution, is an internationally renowned fine artist, an authority on digital printing, and a respected lecturer and workshop leader. Get his enews Insights with access to hundreds of lessons at www.johnpaulcaponigro.comand see more of his panorama tips at www.johnpaulcaponigro.com/downloads/technique/exposure.php.
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