There is a basic image editor built into Auctria you can use to manipulate images.
On the Images tab of the item or donor details page click the Edit icon (green pencil) to open an image in the image editor.
The editor will open in an overlay on the screen:
The most common operations would be to resize, crop or transform (rotate) an image.
After selecting an operation click on Apply to apply it in the editor and then Save to save the changes back to the server.