5 ways to fix Perspective Distortions on iPhone
Perspective distortions in photography come in many different forms. Since I turned to iPhone Photography in 2012, I've tried several apps to fix perspective distortions right on iPhone, but the results I got were, let's say, suboptimal. Many of the apps I tried reduced the overall resolution of the photo.
As of 2019, perspective correction features are available in many iPhone photo apps. In this article, I'll share 5 (actually it's 4 plus 1 as a bonus) different apps I regularly use that offer different features for fixing perspective distortions.
For each app, and that's one of the most important features if you ask me, I'll let you know if the app will retain or reduce the overall resolution of your photo.
Let's start with a short recap about perspective distortion.
What is a perspective distortion in photography?
The mostly encountered kind of perspective distortion is converging or plunging lines. They occur when you photograph a large object, like a building, from the ground level and tilt your camera upwards. Here's an example of what I'm talking about. It's a photo I took in Bucharest, Romania. Notice the red lines I've added that illustrate the plunging lines. In a perfect picture, those lines would be parallel to the edges of the frame which would make the building perfectly upright.
Another kind of perspective distortion is horizontal distortion that occurs, when you're not perfectly aligned with a large object, e.g., a building, or in this case the door that I used as a frame for the Ferris wheel in Chernobyl.
The third kind is barrel distortion that occurs when you use an ultra-wide lens or a fisheye lens like in this photo of an abandoned church near Leipzig.
Luckily for us iPhone photographers, we can fix all those different kinds of distortions right on our iPhone. Today, there are at least 5 apps that will help you with that.
How to fix perspective distortion and barrel distortion on iPhone
Until 2014 only very few apps existed that would allow you to fix different kinds of perspective and barrel distortions. But unfortunately, all of those apps would reduce the overall resolution of your photo if you'd use them to fix distortions. Thus, I didn't use such apps. But that changed in 2014.
Fixing perspective distortions with SKRWT App
In 2014, this fantastic new app appeared on the scene. It touted itself as the missing link in iPhone photography. And yes, it was.
With SKRWT, you can fix all kinds of distortions, be it horizontal, vertical, or barrel distortion. And with an optional in-app purchase, you could even use a freeform edit to fix all other kinds of distortions. I've written a review of SKRWT app here in the blog, and I've been using SKRWT extensively since 2014.
Unlike any other perspective correction app I tried, SKRWT would keep the current resolution of the photo. SKRWT received a lot of praise when it was released, and that praise was well deserved.
Unfortunately, it seems that SKRWT app is not maintained any longer. The last update was released more than two years ago, and there's a bug if use photos that you tool in the new HEIC format that was introduced by Apple a while ago. I sent an email about this bug a while ago and never got any response (or a bugfix release)
As of August 2019, I can confirm what SKRWT still works on iOS13 (beta).
I will keep and use it until it stops working, especially for fixing barrel distortions that occur from the Moment Superfish Lens. In this area, SKRWT is really unbeaten.
But for fixing horizontal and vertical distortions, I've turned to Adobe Lightroom Mobile.
Fixing perspective distortions with Adobe Lightroom Mobile
Sometime in 2018, Adobe updated Lightroom Mobile with functionality that was only available on the Desktop by then. Now you can fix horizontal, vertical and even some barrel distortions on your iPhone or iPad with Adobe Lightroom Mobile.
Adobe calls these adjustments geometry and they're available for Adobe Lightroom CC subscribers. I've hesitated for some time to subscribe to Lightroom. But doing the math and after I saw what's included in a Lightroom Subscription, I finally subscribed a few years ago. No regrets so far.
With Lightroom Mobile, you can basically fix all kinds of perspective distortions:
- Vertical distortions
- Horizontal distortions
- Barrel distortions (but not to the same extent as SKRWT)
- And even a combination of all of the above.
Lightroom Mobile offers three ways to fix perspective distortions:
- A manual way by adjusting the proper sliders for either horizontal, vertical, or barrel distortion
- An automatic way where Lightroom tries to find converging lines and automatically fix them by making them parallel
- A guided way where you draw lines and Adobe adjusts the photo accordingly.
Lightroom offers a way to keep the resolution of the original photo using either the zoom, x-offset or y-offset adjustments or a combination of all three.
Fix perspective distortions with Photos App in iOS 13
With iOS13, Apple has made some updates to the Photos app. One of them is that you can fix horizontal and vertical perspective distortions.
However, by default, those fixes won't keep the current resolution of the photo. You will lose up to 1-2 megapixels unless you're willing to apply a different crop to your photo. Here's an example of what I'm talking about. First, I just fixed the perspective distortion and didn't adjust the cropping. Then I checked the resolution of the photo in the EXIF reader of ProCamera app. Then I adjusted the cropping and checked the resolution again.
For this scenario, the photo has a resolution of 10.3 megapixels (3722 x 2792 pixels)
In the second scenario, the overall resolution actually increased due to the crop I applied. The overall resolution now is 3713 x 3763, which results in a total of 13.9 megapixels.
Please note that the increase of resolution is not due some fancy pixel duplication magic. It's simply because the algorithm that does the perspective correction actually "stretches" the image horizontally and upwards to get the lines straight.
Just keep that in mind when using the perspective correction feature of iOS13.
You can find those perspective corrections adjustments under the crop adjustment group:
- Tap and photo to view it large
- Tap edit in the upper right corner
- Tap the crop and rotation adjustment group in the lower toolbar.
- Swipe left to the vertical or horizontal perspective correction adjustment
- Adjust the slider
Fixing perspective distortions while shooting with Pro Camera App
ProCamera App is one of my favorite camera apps for iPhone.
In 2019, the developers introduced a fancy new feature: automatic perspective correction.
With this feature turned on, you're able to fix converging lines right when you're taking the photo. You even get to see how the auto perspective correction will look like because you get a preview on the screen even before you take the photo. Simply awesome.
Here's a full review of [auto perspective correction in ProCamera] for your convenience.
Fixing perspective distortions with Snapseed
Snapseed is not one of the apps I use regularly, that's why I don't have a review for it. In fact, I rarely use it.
But as SKRWT app is not maintained any longer I looked for an app that supports free form perspective corrections. And that's where Snapseed comes in. You can find this feature under Tools, Perspective and then Free.
So far, I've used it on a few photos only but I'm quite impressed by the results. And, most important, the photos keeps the resolution.
In addition to to the free form perspective correction, Snapseed supports vertical and horizontal fixes. Even with content-aware fill.
Maybe if Snapseed adds a feature that will allow to fix barrel distortions, it could completely replace SKRWT.
Recap and Recommendation for fixing perspective distortions on iPhone
It really depends on the kind of photography you're doing which app I'd recommend.
If you own a fisheye lens, like the Moment Superfish, SKRWT is still the best option; knowing, that the app is currently not maintained any more. So at some point, it may stop working. You can also fix barrel distortion in Lightroom Mobile, but not to the same extent as with SKRWT app. If you want to give it a try, you can get SKRWT from the App Store.
If you just to fix horizontal or vertical perspective distortions, then Adobe Lightroom is a good choice. I really love the guided approach to perspective correction that Adobe implemented. Adobe Lightroom Mobile is available from the App Store.
But if you're an occasional photographer and only need to fix perspective distortions every now and then plus you can live with a slightly reduced resolution, then use the perspective correction features in iOS13 photos app. iOS13 will be available as an automatic update for your iPhone this fall.