Update 03 Apr 2018: This feature is now available in Lightroom for iOS as well.
When I take photos I often like to get the composition as square and upright as I can. If there’s a straight line, like a tabletop or a wall or the contours of a building, I do everything I can to make sure it’s as rectilinear and aligned with the edges of the frame as I can. This isn’t always possible, of course, not just because I can’t always get in the right position to capture an image in that way, but also because of the way camera lenses of all kinds (especially those on phones) tend to visually distort the images they capture.
Some photo editing apps make it pretty easy to fix this, especially on desktop. On mobile, I used to use an app called SKRWT which did a nice job for a while before a disastrous redesign a few years ago rendered the app basically unusable. Since then there hasn’t been a good replacement, but last month Adobe Lightroom CC mobile app added a “geometry” feature that makes this effect easy to do. Finally.
These screen grabs illustrate the process. After importing an image, in this case a shot I took of some theater signage that stood several feet above me, I tap on the new “Geometry” tab in the toolbar at the bottom of the screen. That allows adjustment of the image using sliders to control the distortion, an imprecise but sometimes useful method.
It’s much more satisfying though to tap the small, cross-like icon just above those sliders to manipulate the image more directly, as shown in the middle image above. This is done by using my finger to draw guides on the image itself that the app uses to straighten the image. You can draw as many as four of them along angles in the picture, each one indicating that the image data should be stretched or pinched to appear more square. Because this can dramatically distort the shape of the overall image, the last step is to crop it down to just the usable area. Below you can see the resulting image, where the type in the signage is more or less fully straightened, as if I shot it looking straight on.
This is an incredibly handy feature to have on the go and frankly its execution is superior to SKRWT or anything that came before, in my experience. Unfortunately right now it’s only available on Lightroom for Android which is a little frustrating but iOS users get so many features first or even exclusively that it’s only fair to feel the reverse occasionally. Nevertheless my colleagues at Adobe remind me that the feature has been available on Lightroom for desktop for some time, and assure me that it’ll come to iOS soon too.