Modern image-editing programs are packed with powerful adjustment tools that provide complex algorithms for radically altering the colour, tone, and even content of an image. Despite all this technology, though, you’ll often find that the single best tool for rescuing a poor image is the crop tool.

Do a basic crop
There are many occasions when you crop simply to remove excess areas of the image, not to perform a radical recomposition of your image.

If you have a snapshot portrait of two people, look at the headroom above them. We don’t really need to see the ceiling or sky, so a simple crop will tighten up the image, focus the attention on the subjects, and make them fill the frame more.

Sometimes people will respond to the notion of cropping out the background by saying: “But I wanted to show the room.” However, most of the time, if you want a picture of, say, a room, or a building, or any background element of some kind to be the focus of your picture, then you should be taking be taking that picture and not a portrait. If you want a portrait, that’s a separate photograph altogether.

Putting the horizon in the bottom third of the photo and cropping out the excess sky turns this landscape photo into a much more powerful panorama

Don’t go too small
When you crop, you reduce the total number of pixels in your image. If you plan on printing your image, then you’ll need to be careful about how much you crop. Crop too much, and you’ll have an image that doesn’t have enough resolution to make a decent print.

If you’re printing to an inkjet photo printer, you ideally want around 240dpi (dots per inch) at your given print size. You can probably get away with a resolution as low as 180dpi, but if you go much lower than that, you’ll see a marked softening of your image. Fortunately, as most cameras these days have a high pixel count, you can crop quite a bit before you get down to an image that’s too small for printing.

Look at the aspect ratio
The aspect ratio is the relation of an image’s width to its height. Most DSLRs have an aspect ratio of 3:2, while point-and-shoots have a 4:3 aspect ratio. When you crop, you can choose to preserve the original aspect ratio or crop freely to create a different aspect ratio that works for the image.

For example, a landscape image might look better if you cropped it to a very wide, short aspect ratio, to accentuate its sweeping view. In fact, you may shoot such images with the idea of cropping them later, since it’s not always possible to get the crop that you want in camera.

Crop for better composition
When cropping, think about the same compositional ideas you do when shooting. Your goal is to help the viewer focus on the image’s subject. Any extra information can be left out.

Remember that you can trust your viewer to understand much of the image. For example, we don’t need a lot of sky, water, and sand to determine that a person is on a beach.

When cropping landscapes, you’ll want to think carefully about where you want the horizon. In the top image, we were struck by a sense of Shiprock in New Mexico sticking up out of the great plain upon which it sits. As shot, it’s a little overpowered by sky, though.

By cropping it so that the horizon was lower than the middle, we’ve reduced the amount of foreground that’s visible and increased the sense of the scale of the rock formation. At the same time, we’ve reduced the overbearing sky, and made Shiprock the dominant form.

Practice good crops
Like the rest of your photo skills, cropping is something that improves with practice. Watch out for bad habits – such as leaving too much headroom in the frame, or not filling the frame with only what matters. Over time, you’ll find that this understanding influences your shooting, and that you take fewer images that require cropping.