Use this code for to get a File data Using FilePath,File and FileChooser

Ionic Framework
1 
nativepath: any;
uploadfn(){
   this.fileChooser.open().then((url) => {
  (<any>window).FilePath.resolveNativePath(url, (result) => {
    this.nativepath = result;
    this.readimage();
  }
  )
})
}  

readimage() {
    (<any>window).resolveLocalFileSystemURL(this.nativepath, (res) => {
      res.file((resFile) => {
        var reader = new FileReader();
        reader.readAsArrayBuffer(resFile);
        reader.onloadend = (evt: any) => {
          var imgBlob = new Blob([evt.target.result], { type: 'image/jpeg'});
          //do what you want to do with the file
        }
      })
    })
  }