CarrierWave gaussian blur filter using MiniMagick

image_uploader.rb

class ImageUploader < CarrierWave::Uploader::Base
  include CarrierWave::MiniMagick

  version :blurred do
    process :blur
  end

  def blur(radius=16)
    manipulate! do |img|
      original_path = img.path
      temp_image_path = File.join(Rails.root, 'public', cache_dir, "/blurred_#{File.basename(original_path)}")

      command = "convert #{original_path} -blur 0x#{radius} #{temp_image_path}"
      system(command)

      MiniMagick::Image.open(temp_image_path)
    end
  end
end

to delete /tmp/blurred_....
replace

MiniMagick::Image.open(temp_image_path)

with

file = MiniMagick::Image.open(temp_image_path)
File.delete temp_image_path
file