Jekyll plugin that replaces pictures in Markdown documents by responsive images using jekyll-responsive-mage

markdown-img-picture-replacement.rb

Jekyll::Hooks.register :documents, :pre_render do |document, payload|
  docExt = document.extname.tr('.', '')
  # only process if we deal with a markdown file
  if payload['site']['markdown_ext'].include? docExt
    newContent = document.content.gsub(/!\[(.*)\]\((?:\/?([^\)\:\s]+))(?:\s"(.*)")?\)(?:{:([^}]+)})*/, '{% responsive_image path: \2 alt: "\1" title: "\3" %}')
    document.content = newContent
  end
end

This Jekyll plugin replaces every Markdown pictures in
Markdown documents by responsive images by jekyll-responsive-image's template.

For example:

![Philadelphia's Magic Gardens. This place was so cool!](/assets/images/philly-magic-gardens.jpg "Philadelphia's Magic Gardens")

will be replaced by

{% responsive_image path: assets/images/philly-magic-gardens.jpg alt: "Philadelphia's Magic Gardens. This place was so cool!" title: "Philadelphia's Magic Gardens" %}