fp-z Focal Point Zoom
The zoom or z-dimension value of a focal point of an image. Must be a float between
100, inclusive. The default value is
1, representing the original size of the image, and every full step is the equivalent of a 100% zoom (e.g.
fp-z=2 is the same as viewing the image at 200%). The suggested range is
1–10. For the focal point to be set on an image,
crop=focalpoint must be set as well.