How to correct perspective and straighten objects on photos in iPhone and iPad

Photo cropping functionality on iPhone or iPad has been around for a very long time. Crop allows you to enlarge some part of the image, cutting out the most important thing and not taking into account insignificant details around the edges.

But with the release of iOS 13 and iPadOS 13, operating systems for Apple smartphones and tablets can do more, than just crop or cut. In a standard application «Photo» an opportunity to correct perspective errors.

If when photographing a picture in the gallery you did not hold the iPhone parallel to the wall, then the situation can now be corrected. Now you can also «fix» image of a skyscraper, so that the top does not deviate as you move away from the shooting point. The good news is, that these perspective tools are easy to use. How it works?

How to correct perspective and straighten objects on photos in iPhone and iPad

Imagine, what do you keep in front of you printed photo. If you move the top edge away from you, image will be distorted. In the same way, you can move the left edge and zoom in the right. In ordinary printed photographs, this effect is difficult to see, but still, you significantly change the geometry of the image. Do it with pixels on your finished photo on iPhone or iPad, and the effect will become much more pronounced, because in fact you don’t tilt or rotate the surface.

To correct perspective errors:

1. Open the desired photo in the Photos application and click the Edit button in the upper right corner.

2. Go to Crop.

3. Use the sliders:

  • Straightening (rotates the image in a circle);
  • Vertically (rotates the image about a vertical axis);
  • Horizontally (rotates the image relative to the horizontal axis);

also change the borders of the photo (pull the frame) to rotate the image and correct the perspective.

As you see, using the option Vertically change the perspective on the image. You can use this to fix your crop error or to achieve a more radical special effect.

The tool works vertically for such things, like buildings and railways. The tool works horizontally to fix such things, like paintings on the walls (Where are you, perhaps, moved a little away).

These tools are powerful in themselves, but it’s best to use them for minor fixes. And not because, that the tools themselves are not suitable for work. The problem is, that a radical adjustment of perspective leads to cropping most of the photo. Look at this:

Lines become vertical, but most of the photo is gone.

When you take pictures of everything, which includes parallel lines – building, the road and everything else – these lines will remain parallel, only if they are in the same plane, as the camera sensor. We give a clarifying example. If you are standing in front of a tall building and point your camera directly at it like that, so that the camera and the front of the building are parallel, then the building will look flat and square.

But as soon as you tilt the camera back, to capture the top of this tall building, everything is changing. A rectangular building turns into a trapezoid. It is called «converging verticals», easy to understand why. The vertical lines in the image tend to «vanishing point». With wide angle lens, similar to that used in smartphone cameras, the effect becomes even more pronounced.

Old, pre-digital way to avoid this, consisted of using a special moving lens. She could slide up and grab the top of the building without having to tilt the camera back. The new way involves using the slider in the application.

Surprisingly, converging verticals are often perceived as a defect in photography, while converging horizontals, eg, railway lines or roads, faraway, are considered acceptable compositional techniques.

Compare this to this more subtle fix:

You can also fix crop errors and do so, that you will look right in front of the subject while taking the picture.

Also worth a try button «Auto» in the cropping section, since she often manages to pretty accurately guess, what exactly needs to be done.

More advanced photo tools

Now, when perspective editing is built into the application «Photo», third-party perspective correction apps may seem a little pointless. But some of them still offer powerful features. for instance, Google’s Snapseed Can Fill In The Gaps, left by tools. This leads to less radical changes, as seen in the picture. But in most cases, you can very well rely on powerful built-in application tools «Photo».