With the image API, how do I crop a image if I don't know the actual dimension of the original image? like the documentation says you can crop by saying

/0x0:400x400

which will take the first 400 pixels top left, but if the original image is like 4000 pixels wide, it will crop out most of the image. I want it to just make it squared without stretching it, so if width is more than height, it should take the height and crop the width on the sides to make it same as height