This gem allows you to easily use MiniMagick to crop and resize images in your Jekyll project, according to a preset defined in your config file.

Install the gem:

[sudo] gem install jekyll-minimagick

In a plugin file within your Jekyll project's _plugins directory:

# _plugins/my-plugin.rb
require "jekyll-minimagick"

Define presets in your _config.yml file, like this:

# _config.yml
mini_magick:
	thumbnail:
		source: img/photos/original
		destination: img/photos/thumbnail
		resize: "100x100"
	medium:
		source: img/photos/original
		destination: img/photos/medium
		resize: "600x400"

This configuration will create a 100x100 thumbnail for each image in img/photos/original and put it in _site/img/photos/thumbnail and a 600x400 image in _site/img/photos/medium.

Already using bundler to manage gems for your Jekyll project? Then just add

gem "jekyll-minimagick"

to your gemfile and create the following plugin in your projects _plugins directory. I've called mine bundler.rb. This will automatically require all of the gems specified in your Gemfile.

# _plugins/bundler.rb
require "rubygems"
require "bundler/setup"
Bundler.require(:default)