I would like to use jpegoptim or optipng to compress the image uploaded by users via Paperclip.

I have a Paperclip model configured as:

  has_attached_file :image,
                    :styles => {:thumb => '50x50>', :preview => '270x270>' },
                    :url => "/system/:class/:attachment/:id/:basename_:style.:extension",
                    :path => ":rails_root/public/system/:class/:attachment/:id/:basename_:style.:extension"

Question 1: Is it possible to compress the original image uploaded by user, then let Paperclip resize it , so there's only one compress process? and how to do it?

Question 2: I am going to do it via the after_post_process callback, and I could get all the instances of three files from image.queued_for_write and I would like to trigger jpegoptim/optipng by the file extension, but when I use current_format = File.extname(file.path), I get something like: .jpg20120508-7991-cqcpf2. Is there away to get the extension string jpg? or is it safe that I just check if the extension string is contained in that string?

ruby-on-rails-3 paperclip
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