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Grunt Image Embed

This task converts all data found within a stylesheet (those within a url( ... ) declaration) into base64-encoded data URI strings. This includes images and fonts.

Created by Eric Hynds @erichynds with major contributions from dancingplatypus.


  • Supports both local & remote images.
  • Ability to specify a size limit. Default is 32kb which is IE8's limit.
  • Existing data URIs will be ignored.
  • Skip specific images by specifying a directive comment.
  • Ability to purge images that have been encoded
  • Includes two helpers: encode_stylesheet to encode a stylesheet, and encode_image to encode an image.

Getting Started

Install this plugin with the command:

npm install grunt-image-embed

Next, add this line to your project's grunt file:


Lastly, add configuration settings to your grunt.js file (see below).


This task has two required properties, src and dest. src is the path to your stylesheet and dest is the file this task will write to (relative to the grunt.js file). If this file already exists it will be overwritten.

An example configuration looks like this:

  imageEmbed: {
    dist: {
      src: [ "css/styles.css" ],
      dest: "css/output.css",
      options: {
        deleteAfterEncoding : false,
        preEncodeCallback: function (filename) { return true; }

Optional Configuration Properties

ImageEmbed can be customized by specifying the following options:

  • maxImageSize: The maximum size of the base64 string in bytes. This defaults to 32768, or IE8's limit. Set this to 0 to remove the limit and allow any size string.

  • baseDir: If you have absolute image paths in your stylesheet, the path specified in this option will be used as the base directory.

  • deleteAfterEncoding: Set this to true to delete images after they've been encoded. You'll want to do this in a staging area, and not in your source directories. Be careful.

  • preEncodeCallback: function that takes full path to the image to be encoded and returns either true (proceeed with default encoding), false (abort the encoding, fail with error) or String, which will be used as the result of the encoding.

  • regexInclude - Regular expression testing against file types to include. Defaults to all (/.*/g). To only include images, you might set this to /\.(jpg|png|gif|jpeg)/gi.

  • regexExclude - Regular expression testing against file types to exclude. Defaults to none (``/$^/g). To exclude fonts for example, you might set this to/.(eot|woff|ttf|svg)/gi`.

Skipping Images

Specify that an image should be skipped by adding the following comment directive after the image:

background: url(image.gif); /*ImageEmbed:skip*/


Version >= 0.3.0 of this plugin is compatible with Grunt 0.4.x. Versions 0.0.1 through 0.2.0 are only compatible with Grunt 0.3.x.


Copyright (c) 2013 Eric Hynds (@erichynds) Licensed under the MIT License.