[miggi]

(I work at imgix)

There are a number of different ways that crops can be made including custom rectangle cropping via pixel or percentage values, provided as url string parameters. The face zoom crop is just an additional feature to save some steps for these kinds of scenarios. Ideally this feature can be built into an application providing a user with a suggested face crop, and then allow a to use the alternate custom crop that access a different set of parameters via imgix. imgix is an on demand dynamic api for these operations.