WordPress has a basic image editing tool that allows you to perform some simple manipulation with your uploaded images. You’re able to rotate and flip your images as well as scale them and crop them to different sizes. When editing the properties of an image (as opposed to other file types like documents or PDFs), click the Edit Image button just below the thumbnail to show the image editing tools.
Just above the image you'll find the following image editing buttons:
Crop – Click on the image and drag the selection box to the size that you’d like the image cropped. Click the Crop button to crop the image to the new size.
Rotate counter-clockwise – Rotate the image 90° counter-clockwise.
Rotate clockwise – Rotate the image 90° clockwise
Flip vertically – Flip the image vertically
Undo – Undo the last change
Redo – Redo the last change
Click the Scale Image link to resize the image proportionally. For best results, scaling should be done before performing any other operations like cropping, rotating, etc.. To scale your image to a new size, simply enter the width or height dimensions in the appropriate field (w x h) and click the Scale button. After entering one value, the other value will change automatically so as to keep the image in proportion. The original image dimensions are displayed just above the input fields, for your reference.
There are several ways to crop your image. The easiest is to simply click on the image and drag the selection box to the appropriate size. If you’d like your image cropped to a specific ratio, enter the values in the Aspect Ratio input fields (e.g. 1:1 (square), 4:3, 16:9 & etc.). You can then hold down the shift key and drag one of the edges of your selection to enlarge or reduce the size, while keeping this aspect ratio locked. If there is already a selection made, specifying the aspect ratio will automatically change the selection to match it.
Whenever the selection box is adjusted, the dimensions are displayed in the Selection input fields. You can also manually enter the dimensions of the selection box (in pixels) by entering values into these two fields. Once your selection box is adjusted, simply click the Crop button just above the image to crop the image to this new size. By selecting one of the options in the Thumbnail Settings panel, you have the option to apply your changes to All image sizes, just the Thumbnail image or All sizes except Thumbnail.
Click the Save button to save your changes. Click the Update Media button to return to the main Media Library page. If you’d like to revert back to your original image, click the Edit Image button again to return to the image editor. A new Restore Original Image link is displayed just below the Scale Image link. Click the Restore Original Image link and then click the Restore image button to discard your changes and restore your original image.