tasks/responsive_images.js
function(engine) {
    if (typeof GFX_ENGINES[engine] === 'undefined') {
      return grunt.fail.warn('Invalid render engine specified');
    }
    grunt.verbose.ok('Using render engine: ' + GFX_ENGINES[engine].name);

    if (engine === 'im') {
      return gm.subClass({ imageMagick: (engine === 'im') });
    }

    return gm;
  }
function(engine) {
    if (typeof GFX_ENGINES[engine] === 'undefined') {
      return grunt.fail.warn('Invalid render engine specified');
    }
    grunt.verbose.ok('Using render engine: ' + GFX_ENGINES[engine].name);

    if (engine === 'im') {
      return gm.subClass({ imageMagick: (engine === 'im') });
    }

    return gm;
  }
function ( engine ) { if ( typeof GFX_ENGINES [ engine ] === 'undefined' ) { return grunt . fail . warn ( 'Invalid render engine specified' ) ; } grunt . verbose . ok ( 'Using render engine: ' + GFX_ENGINES [ engine ] . name ) ; if ( engine === 'im' ) { return gm . subClass ( { imageMagick : ( engine === 'im' ) } ) ; } return gm ; }
Set the engine to ImageMagick or GraphicsMagick

@private
@param  {string}          engine     im for ImageMagick, gm for GraphicsMagick
Set the engine to ImageMagick or GraphicsMagick