Thumbnailing PDFs with MiniMagick

Maybe this was already out there somewhere, but my search fu failed. So, for the benefit of anyone else using MiniMagick instead of RMagick and needing thumbnails of PDF files:

image=MiniMagick::Image.open("some.pdf")
image.format("png", 1)
image.resize("200x200")
image.write("some_thumbnail.png")

Or in CarrierWave:

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

  version :web_thumb do
    process :thumbnail_pdf
  end

  def thumbnail_pdf
    manipulate! do |img|
      img.format("png", 1)
      img.resize("150x150")
      img = yield(img) if block_given?
      img
    end
  end

end