Wirtin root path using file column

i want the imagesto be written to directory outside the rails
app using the file_column.
MY RAILS_APP PATH:/var/www/domain.in/rails_app

i want the images to be uploaded to a directory to

the model is as below

class Entry < ActiveRecord::Base

    file_column :image, :magick => {
  :versions => { "thumb" =>"50x50"}
},{:root_path => "/var/www/domain.in/"}

the image upload is not happenin to the above specified path?it still
happens in the /rails_app/public/model etc…etc…

is there something that i’m missing??