If you are using file_column to upload images, you can directly process the images with RMagick, a ruby extension for accessing the popular imagemagick libraries. You can find more information about RMagick at rmagick.rubyforge.org.

You can control what to do by adding a :magick option to your options hash. All operations are performed immediately after a new file is assigned to the file_column attribute.

To resize the uploaded image according to an imagemagick geometry string, just use the :geometry option:

   file_column :image, :magick => {:geometry => "800x600>"}

You can also create additional versions of your image, for example thumb-nails, like this:

   file_column :image, :magick => {:versions =>
     { "thumb" => "50x50", "medium" => "640x480>" }
   }

These versions can later be accessed via file_column’s suffix mechanism. So if the uploaded image was named "vancouver.jpg", you can access the additional versions like this:

   o.image("thumb") # produces ".../vancouver-thumb.jpg"
   o.image_relative_path("medium") # produces ".../vancouver-medium.jpg"

The same mechanism can be used in the url_for_file_column helper:

   <%= url_for_file_column "entry", "image", "thumb" %>

Note: You‘ll need the rmagick extension installed as a gem in order to use file_column’s rmagick integration.