Intervention / Image Upload Error {{ Image source not readable }}

Hello i am trying to add a profile upload image in Laravel "5.1" . I used the Intervention/Image Package but when i try to upload the image i am getting this error:

"NotReadableException in AbstractDecoder.php line 302: Image source not readable"

This is my PhotoController:

<?php

namespace App\Http\Controllers;

use Illuminate\Http\Request;
use Image;
use Input;
use App\Http\Requests;
use App\Http\Controllers\Controller;



class PhotoController extends Controller
{
    /**
     * Display a listing of the resource.
     *
     * @return \Illuminate\Http\Response
     */
    public function index()
    {
        //
    }

    /**
     * Show the form for creating a new resource.
     *
     * @return \Illuminate\Http\Response
     */
    public function create()
    {
        //
    }

    /**
     * Store a newly created resource in storage.
     *
     * @param  \Illuminate\Http\Request  $request
     * @return \Illuminate\Http\Response
     */
    public function store(Request $request)
    {

        $img = Image::make($request->file('photo')); 
        $img->save('image.png');  
    }

    /**
     * Display the specified resource.
     *
     * @param  int  $id
     * @return \Illuminate\Http\Response
     */
    public function show($id)
    {
        //
    }

    /**
     * Show the form for editing the specified resource.
     *
     * @param  int  $id
     * @return \Illuminate\Http\Response
     */
    public function edit($id)
    {
        //
    }

    /**
     * Update the specified resource in storage.
     *
     * @param  \Illuminate\Http\Request  $request
     * @param  int  $id
     * @return \Illuminate\Http\Response
     */
    public function update(Request $request, $id)
    {
        //
    }

    /**
     * Remove the specified resource from storage.
     *
     * @param  int  $id
     * @return \Illuminate\Http\Response
     */
    public function destroy($id)
    {
        //
    }
}

This is my html form:

<header>
                <div class="student_profile_sub_header w100">
                    <div class="container ccenter">
                        <div class="student_profile_name">
                            <h4>{{$student->name}} {{$student->surname}}</h4>
                        </div>
                        <div class="student_profile_image">
                            <img src="{{asset('assets/profile_image.png')}}">
                        </div>

                        <form method="POST" action="../student/profile/imageupload">
                            {!! csrf_field() !!}
                            <input type="file" name="photo">
                            <input type="submit" value="Upload Image" name="submit">
                            @foreach($errors->all() as $error)
                                <li>{{ $error }}</li>
                            @endforeach
                        </form>
                    </div>
                </div>
            </header>

via Chebli Mohamed