var extent = _wktParser.readGeometry(_result.wkt).getExtent();
                 _imageLayer = new ol.layer.Image({
                                    name: 'Query',
                                    opacity: 0.8,
                                    map: _map,
                                    visible: true,
                                    source: new ol.source.ImageStatic({
                                              imageExtent : extent,
                                              projection : bbox.epsg,
                                              url : 'data:image/png;base64,'+ _result.image64
                                              })
                   });
_map.addLayer(_imageLayer);