New api call: getImageMeta()

 Returns the following image properties (which are not tags but still very handy to have when processing images):

    { fileName: '/path/books.jpg',
      fileSize: '993738',
      mimeType: 'image/jpeg',
      pixelHeight: '1200',
      pixelWidth: '1600' }

Exiv2 also outputs these by default, along with the high level summary exif tags.