Problem solved, in case anyone is having the same issue, this is what I added in the app.run method:
document.addEventListener('resume', function(evt) {
if(evt.action === 'resume' && evt.pendingResult) {
var r = evt.pendingResult;
if(r.pluginServiceName === 'Camera' && r.pluginStatus === 'OK') {
var restoredImageData = r.result;
}
}
}, false);