在rest api中的Codeigniter图像上传问题

I have an issue with image upload in codeigniter 3. when I upload images with postman its working fine.what when a request made from android its giving error the filetype is not allowed.when I further check in upload.php library its seems that its not handling file extenstion.My config for upload libray are:

$config['allowed_types']='jpg|png|jpeg';

and request from android is(post and file data)

{
  "post": 
    {
     "user_id":"1003",
     "car_id":"1",
     "address":"xxdrtxr",
     "location":"Delhi",
     "loaner_vehicle":"1",
     "enquiry":"fdf",
     "service_type":"1",
     "pick_up_date":"13\/9\/2018",
     "pick_up_time":"01-02 PM",
     "latitude":"30.6967858",
     "longitude":"76.6877732"
   },
  "files":{
     "service_images":
     {
       "name":["20180904_164537.jpg","20180904_164329.jpg"],
       "type":["multipart\/form-data","multipart\/form-data"],
       "tmp_name":["\/tmp\/phpdCkPPH","\/tmp\/phptvFq7C"],
       "error":[0,0],"size":[1077267,782637]
      }
   }
 }