You can use Markdown inside the questions and answers! Images in the same folder though.

anki.rb

#!/usr/bin/env ruby

# Usage:
#
# => brew install imagemagick
# => gem install anki2 kramdown rmagick image_optim image_optim_pack
# => chmod +x ./anki.rb
# => ./anki.rb questions.md

require 'rubygems'
require 'yaml'
require 'anki2'
require 'kramdown'
require 'rmagick'
require 'image_optim'

# Transforms `$` into `[$$]` and `[/$$]`.
def fences(str)
  toggle = true
  str = str.gsub(/\${1}\s{1}/, '[$$] ')
  str = str.gsub(/\s{1}\${1}/, ' [$$]')
  while str =~ /\[\${2}\]/ do
    if toggle
      str = str.sub(/\[\${2}\]/, '[$$/]')
      toggle = false
    else
      str = str.sub(/\[\${2}\]/, '[/$$]')
      toggle = true
    end
  end
  str = str.gsub(/\[\${2}\/\]/, '[$$]')
end

# Markdown to HTML. Known issue: Kramdown ignores `$$` for some reason.
def markdown(str)
  str = str.gsub(/\${2}/, '$')
  str = Kramdown::Document.new(str).to_html
  str = fences(str)
end

# Open the file from command line params
file = File.new(ARGV[0], 'r')
arr  = file.read.split('---')
file.close

# Read the front matter and media folder
meta  = YAML.load(arr[0].strip)
media = meta['Media'] || '.'
@anki = Anki2.new(name: meta['Deck'], output_path: meta['File'])
puts "--> Generating deck \"#{meta['Deck']}\"\n"

# Read images from media
images = Dir.glob("#{media}/*.{png,jpg,jpeg,gif}")

# Resize the images before optimizing
puts "--> Resizing #{images.count} images\n"
images.each do |name|
  image = Magick::Image.read(name).first
  image.change_geometry("800") do |cols, rows, img|
    img = img.resize!(cols, rows)
    img.write(name)
  end
end

# Optimize images before packing
image_optim = ImageOptim.new(:pngout => false, :svgo => false)
images.each do |name|
  puts "--> Optimizing #{name}\n"
  image_optim.optimize_image!(name)
end

# Add the media folder
@anki.add_media(media)

# Add cards to the deck
deck = arr[1..-1]
deck.each do |card|
  content  = card.split(/(Q:|A:)/)
  question = markdown(content[2].strip)
  answer   = markdown(content[4].strip)
  @anki.add_card(question, answer)
end

# Pack and save the cards
puts "--> Packing #{deck.count} cards\n"
@anki.save
puts "--> Done!\n"

questions.md

Deck: "Physics"
File: "Mechanics.apkg"

---

Q: What is the formula for the gravitational potential energy $$ U_g $$?

A: $$ U_g = m g h $$ [J].

---

Q: What is the formula for the spring potential energy $$ U_s $$.

A: $$ U_s = \frac{1}{2} k |x|^2 $$ [J].