pngcrush-bin 
pngcrush is an optimizer which main purpose is to reduce the size of the PNG IDAT datastream by trying various compression levels an PNG filter methods
Install
$ npm install --save pngcrush-bin
Usage
var execFile = require('child_process').execFile;
var pngcrush = require('pngcrush-bin').path;
execFile(pngcrush, ['-reduce', '-brute', 'input.png', 'output.png'], function (err) {
if (err) {
throw err;
}
console.log('Image minified');
});
CLI
$ npm install --global pngcrush-bin
$ pngcrush --help
License
MIT © imagemin