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imacss Build Status

pronunciation: imax

An application and library that transforms image files to data URIs (rfc2397) and embeds them into a single CSS file as background images.

Let's say you have a web-based frontend which embeds a lot of images (e.g. icons). This referencing produces HTTP requests for every single image. What if you would like to minimize it to just one request? That is something imacss can do for you.


Okay, enough words. Let's dive straight into a transformation example. If we assume that you have two SVGs, like github.svg and quitter.svg, imacss will generate this CSS code for you.

.imacss.imacss-github {
.imacss.imacss-quitter {

You can refer to this images by using the respective CSS classes:

<div class="imacss imacss-quitter">...</div>


imacss comes with a command-line interface which pipes the output to stdout by default (yeah, plain old text streams FTW!).


Install with npm globally.

npm install -g imacss

Usage examples

Embed all SVGs in a particular directory and all its subdirectories (will pipe the output to stdout).

$ imacss "~/projects/webapp/images/**/*.svg"

Embed all SVGs in a particular directory and transfer them to a CSS file which will be saved in the CWD.

$ imacss "~/projects/webapp/images/*.svg" > images.svg.css

Embed all SVGs and PNGs in a particular directory and transfer them to a CSS file which will be saved in the CWD.

$ imacss "~/projects/webapp/images/*.{svg,png}" > images.css

If you don't like the imacss selector namespace you are able to modify it as well.

$ imacss "~/projects/webapp/images/*.{svg,png}" foobar > images.css

will produce this selector structure in the CSS file:

.foobar.foobar-github {...}

Important: Please note that imacss does not embed image/svg+xml as base64 strings. Instead it will use the raw utf-8 representation.


If you would like to use the imacss functionality within your application, there is an API for that.


Install with npm

npm install --save imacss


transform(glob[, namespace]);

Transforms the image files from the specified glob and returns a stream with the CSS selectors that can be piped to somewhere else.



String || Vinyl file object

The path to the images which should be transformed. You can use any glob pattern you want or you're also able pass single Vinyl file objects.

namespace (optional; default=imacss)

String || Function

A string containing the css class namespace prefix, or a function to generate the entire CSS ruleset.

The CSS selector namespace.

Usage example

var imacss = require('imacss');
    .on('error', function onError (err) {
        console.error('Transforming images failed: ' + err);

Passing a function to customize the resulting CSS rule set

var imacss = require('imacss');
function generateCss(image) {
    return '.image-' + image.slug + ' { ' + 'background-image:' + 'url(\'' + image.datauri + '\'); }';
    .transform('/path/to/your/images/*.png', generateCss)
    .on('error', function (err) {
        console.error('Transforming images failed: ' + err);


Copyright 2014 - 2015, André König (