Relies on the `twitter-text` and `postgres_ext` gems. Model methods on a "Post" model with an `images` column (array of strings) and `text` column (the post's text)

Image Extractor

class Post < ActiveRecord::Base
  include Twitter::Extractor

  def parse_images
    images_array = Array.new
    extracted_links.each do |link|
      if looks_like_an_image?(link)
        url = URI.parse(link)
        Net::HTTP.start(url.host, url.port) do |http|
          if http.head(url.request_uri)['Content-Type'].start_with? 'image'
            images_array << link
          end
        end
      end
    end
    self.images = images_array
  end

  def looks_like_an_image?(url)
    if url[/(?:png|jpe?g|gif|svg)$/]
      return true
    else  
      return false
    end
  end

  def extracted_links
    extract_urls(self.text)
  end
  
end

Ah, neglected to mention that this runs as a before_create.

before_create :parse_images