downsample attachment_fu images, rake task

gistfile1.rb

# downsample large attachment_fu images
namespace :images do
  desc "Downsample Large Images"
  task :downsample_large => :environment do
    count = Image.large.count # named scope
    chunk_size = 500
    (0...(count/chunk_size)).each do |i|
      images = Image.large.find(:all, :offset=>i*chunk_size, :limit=>chunk_size).each do |image|
        image.downsample!(55)
      end
    end
  end
end