Sometimes, you want to change the focus or attention in an image. Cropping an image is an easy way to do that.
An often overlooked tool on Macs is the application Preview. Open your image in Preview and we will begin.
Apple Preview — Free with your Mac 
Sample image opened using Preview
This image of a dessert was taken vertically, and I’d like to make it more of a horizontal image. The easiest way is to crop it down.
When you open an image, the Rectangular Selection tool is the default.
Move your cursor over the image to the upper left corner of the area you want to crop.
Click, hold and then drag to lower right corner, and release your click.
Tweaking the selection
You can now adjust your selection using the dots or handles around it. Click and drag a handle to resize your selection rectangle.
Move your cursor inside the rectangle and the cursor changes to a hand. Click and drag and it will move the rectangle without changing its size. If you click outside the selection, it will disappear releasing it and you will hav to make a selection again.
Cropping
Once you have your selection to your liking, go to the menubar, click on Tools, and then click Crop. Also, if you like to use keyboard shortcuts, you can press CMD-K.
Just desserts!
Your image is now cropped. Notice a few things have now changed.
Notice the red close button now had a dark dot in it, and the filename has “— Edited” after it. If you save your file now, it will overwrite the orginal.
Making Copies
From the menubar, select File>Duplicate.
Name it
A new window opens with the name selected.
Enter a new name for the cropped image and it is saved in the same folder as the orginal.
Getting back to your origins
Click the red close button on the cropped image’s window. Since it was saved when you named it, the window just disappears.
Clicking the red close button on the original, results in this warning.
Click Revert Changes to keep your original in tact. If click Save, you orignal will be overwritten with the cropped version.
In a nutshell
- Open your image in Preview
- drag a selection rectangle the the area you want.
- Select Tools>Crop (CMD-K)
- Select File>Duplicate (CMD-SHIFT-S)
- Name it.
- Close your open windows.
If this has been helpful or confusing, leave a comment.