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Plugin Information


Add a caption tag to Jekyll



A Liquid tag for Jekyll sites that allows easy creation of captioned
images like they are in WordPress.

How To Install

  1. Install all required gems: dimensions, rmagick (sudo gem install dimensions rmagick on Debian-based machines)
  2. Copy caption_tag.rb into <your-jekyll-site>/_plugins.
  3. Add the styles from style.css to your stylesheets.
  4. The thumbnails get created in <your-jekyll-site>/captions. Make sure that you don't use this folder.
  5. After every site generation, move <your-jekyll-site>/captions to <your-jekyll-site>/_site/captions.

How To use

Place a caption tag in your content file, e.g.:

{% caption align="aligncenter" width="512" height="233" alt="The order of points is important for the definition of a polygon" caption="[A, B, C, D, E, F, G] != [A, B, C, D, F, E, G]" url="../images/2013/11/polygon-order.png" %}
Attribute Details
align The content of this will be added to the class of the surrounding <div>.
width The width of the image.
height The width of the image.
alt The alternative attribute for images.
caption The text below the image.
url The source (src) of the image.

Global configuration options

You can place the following options in your _config.yml file:

Attribute Default Details
caption_max_width "512" The maxiumum width captions may have when you don't specify it.
caption_max_height "800" The maximum height captions may have when you don't specify it.
caption_folder "/captions" The folder where captions get stored.



  • Version 1.8, 2014-04-18:
    • Check and fail if url attribute is missing.
    • Fix for a problem that occured when image was smaller than the specified width.
  • Version 1.7, 2014-04-18:
    • Relative URLs check path relative to the pre-generation post first. If no image is found then the root source folder is taken as base.
    • Fixed get_online_url to use the caption folder (see issue #6).
  • Version 1.6, 2014-04-18:
    • Fixed issue (generated caption images were not used)
  • Version 1.5, 2014-04-13:
    • Added global configuration options
    • Added check if image was already scaled
    • Added logger
  • Version 1.4, 2014-03-27:
    • Fixed issue (if two files had the same name, but were in different folder the captions were overwritten)
  • Version 1.3, 2014-03-24:
    • Captions can resizes automatically to a given maximum size while preserving the aspect ratio.
  • Version 1.2, 2014-01-07:
    • The enclosing div is now 10px wider than the img inside.
  • Version 1.1, 2014-01-07:
    • Just take the URL that was given, don't add anything.
    • Close image tag
  • Version 1.0, 2014-01-02: Initial commit.


This code is licensed under MIT License.

What does this mean?

  • You may use it if you like
  • Don't blame me when thinks don't work (though you can file an issue)
  • Please don't remove the link in the comments of caption_tag.rb. This might help others to find this plugin


I have a generated rdoc documentation.

It was generated with this command:

rdoc --exclude=/doc


  • Try to get rid of step 5 of "how to install".