If your website allows users to upload photos, image cropping/resizing functionality certainly comes in handy. But users might not have access to image manipulation tools like Photoshop, so by providing a cropping/resizing feature you can allow users to upload photos from any device (e.g. tablets or phones) without them having to worry about the the final size. Furthermore, you can create different versions of the same image and also allow users to crop specific portions of uploaded picture. In this article I’ll show you how to create an image cropping tool with the help of the ImageMagick PHP extension.
The post shows the use of the "cropimage" function to trim down an image from its original size and "thumbnailImage" to shrink down the image to make a thumbnail. Also included is the code (both the PHP and the HTML form) to handle file uploads and automatically create a thumbnail image. It outputs the image to the browser and asks the user to select the portion they want thumbnailed (with this jQuery plugin helping).