How to Crop a Picture
Using the crop tool to edit a photo can improve the image dramatically. By selecting the area that has the greatest impact, or cropping, your photos will have more appeal for viewers.
Begin by deciding which part of the photo is most interesting. Then select that area to be cropped. For most photos, you'll want to set the crop to "unconstrained," allowing your to use any proportions that best suit the composition. Unconstrained is the default setting for crop photo tool in most editors.
If you have a specific use for the photo, such as making a print or including it in a slideshow, the your may want to constrain crop to specific proportions, such as "5x7" for an inkjet print or 16:9 for a slideshow.
In Luminar, for example, click on the Ratio setting to reveal the popup menu offering you options for Free (unconstrained), Original (keeping the crop to the original proportions of the picture), and then preset ratios, such as 1:1 (popular for Instagram) and 3:2.
When a ratio setting is used, the crop tool will only draw to those dimensions. After your first attempt to select an area in the photo with the crop adjustment, you can finetune your selection by grabbing a handle on any corner of the cropping frame and dragging inward or out to change its size.
You can also move the frame around the composition, or move the subject inside the frame depending on the software, to perfect the composition. Once everything is set to your liking, then click on the Apply button (or OK) to set the crop for the photo and complete the adjustment.
Some applications, such as Photoshop and Luminar, also allow you to crop to size. So, for example, if you know that you want the dimensions to be 1200 pixels by 800 pixels, you can enter those measurements in the size fields for cropping.
Doing this not only sets the pixel dimensions of your cropped photo, but also constrains its proportions. So you are actually accomplishing two tasks at once.
Another feature that has become more common in the crop adjustment is Straighten. Lightroom, Photos for macOS, and Luminar all include this adjustment. So if your horizon is slightly off kilter in the photo, you can correct it by applying straighten in the crop settings.
And finally, be aware whether your application is non-destructive or a destructive editor. Non-destructive editors such as Lightroom, Luminar, and Photos for macOS, allow you to change your mind and go back and re-crop, or even restore the file to its original dimensions.
Photoshop, on the other hand, is a destructive image editor. So if you want to retain all the information from the original photo before cropping, it's best to duplicate it first, then use crop.
You'll be happily surprised at how much your pictures improve by adding crop to your standard editing workflow.