dbrockman / pngsize

Get the width and height of a PNG image or buffer.

PNG size function

npm install pngsize

Function that reads the width and height of a PNG image by checking the IHDR header chunk. The function will only read the first 24 bytes of the file.

The function will also validate the PNG file signature.

var pngSize = require('pngsize');

//// Async
pngSize('image.png', function (err, size) {
  if (err) {
    // Error in fs.open, fs.read, fs.close
    // or the PNG signature is invalid.
  } else {
    console.log('size of image.png: %s x %s', size.width, size.height);
  }
});

//// Sync
try {
  var size = pngSize('image.png');
  console.log('size of image.png: %s x %s', size.width, size.height);
} catch (err) {
  // Error in fs.openSync, fs.readSync, fs.closeSync
  // or the PNG signature is invalid.
}

//// Read PNG data from buffer
// Note that pngSize only needs the first 24 bytes.
// Calling pngSize with a buffer will not throw an error if
// the signature is invalid but will return null.
var buffer = fs.readFileSync('image.png');
var size = pngSize(buffer);
if (size) {
  console.log('size of image.png: %s x %s', size.width, size.height);
} else {
  // the signature is invalid or buffer.length < 24
}