Set uploaded image  resizeness only for images except for files, docs or others.

  version :thumb, :if => :image? do
    process :resize_to_fit => [197, 229]
  end

  version :banner, :if => :image? do
    process :resize_to_fit => [1024, 328]
  end

  version :post, :if => :image? do
    process :resize_to_fit => [700, 400]
  end

  protected

  def image?(file)
    file.content_type.include? 'image'
  end


Thanks,
Hemant Gupta