Pngcrush NPM | npm.io

node-pngcrush

The pngcrush command line utility as a readable/writable stream. This is handy for situations where you don't want to worry about writing the input to disc and reading the output afterwards.

The constructor optionally takes an array of command line options for the pngcrush binary:

var PngCrush = require('pngcrush'),
  myCrusher = new PngCrush(['-res', 300, '-rle']);

sourceStream.pipe(myCrusher).pipe(destinationStream);

PngCrush as a web service (removes all ancillary chunks and does brute force compression):

var PngCrush = require('pngcrush'),
  http = require('http');

http
  .createServer(function (req, res) {
    if (req.headers['content-type'] === 'image/png') {
      res.writeHead(200, { 'Content-Type': 'image/png' });
      req.pipe(new PngCrush(['-brute', '-rem', 'alla'])).pipe(res);
    } else {
      res.writeHead(400);
      res.end('Feed me a PNG!');
    }
  })
  .listen(1337);