The Rolling Stones claim, “You can’t always get what you want”.
And when your application needs to crop hundreds or thousands of images to specific sizes within a strictly defined UI design, that frustrating Rolling Stones phrase may be ringing in your ears.
But maybe it doesn’t have to.
There’s no feasible way to crop so many images manually, especially for user-generated content that must be displayed immediately. What you really need is a way to automatically crop all those images to fit your design (or even multiple, responsive designs for different devices). But you need to feel confident that the main area of interest will remain in the final cropped images, regardless of the varied sizes, content, and layout of the original images.