Send image from filesystem to server in AngularJs

I need to send in background multiple-image and some data to server.

I'm using ionicframework (with angularjs) for my android app. I'm using angular-file-upload (directive) and the following code is my factory:

if(angular.isArray(arrPictures) && arrPictures.length > 0) {

       var files = [];
       for(var i=0; i<arrPictures.length; i++) {
           files.push(arrPictures[i].photo); //it is like file://my_path/myImage.jpg
       }

        $upload.upload({
            url: API_POST_ANSWER,
            method: 'POST',
            data: {
                "idSurvey": idSurvey,
                "idOAM": idOAM,
                "idOPM": idOPM,
                "score": score,
                "date": date,
                "answerJson": answersJson,
                "address": address,
                "latitude": latitude,
                "longitude": longitude
            },
            file: files,
            fileFormDataName: "pictures"
        }).progress(function (evt) {
            //progress
            alert('progress: ' + parseInt(100.0 * evt.loaded / evt.total) + '% file :'+ evt.config.file.name);
        }).success(function (data, status, headers, config) {
            // file is uploaded successfully
            alert('file ' + config.file.name + 'is uploaded successfully. Response: ' + data);
        }).error(function (ex) {
            //error
            alert("error");
            alert(ex);
        });

   } 

Now i have a problem because the server get strings (path string) and not files My question is "How i can convert my path string into file object to send it currectly to the server?"