Use sips command on mac to trim bottom of image

I want to write a batch command script for osx that will crop off the bottom of an image. Is that possible using sips?

I have a bunch of images 640 x 1136 and I want crop them (not scale or resize) to 640 x 960. When the image is cropped, I want the bottom of the image removed and the top to stay the same. Basically, I just want to cut the bottom of the image off.

I have this but it's cropping both from the top of the image and bottom.

sips --cropToHeightWidth 640 960

How do I save a cropped image on a Mac?

Cropping Images Faster in Preview with Keyboard Shortcuts The selector tool should be immediately active and visible by default with a picture open, so draw the rectangular selection around the region to crop down as usual. Now hit Command+K to crop the image. Finally, hit Command+S to save the cropped picture.

Doesn't look like it's possible. Thanks guys.