Cut X pixels from the image's bottom with paperclip

Question

I have some images from which I need to cut the last 30 pixels.

I read this Cutting x pixels from an image and I think this should work, but is for imagemagick and I don-t know how to translate it to Paperclip.

I searched many places and I couldn't get a straightforward answer. . . seriously don't get how can it be so complicated, why can't we have a method or something to do it, it seems like something so basic.

Answer 1

I ended up using Devil after saving the image

 Devil.with_image(page.picture.path) do |img|
     img.crop(0,85,img.width,img.height-85)
     img.save
  end