I have installed OpenCV lately and I cannot use imread().

This is my code

#include <opencv2/core/core.hpp>
#include <opencv2/highgui/highgui.hpp>
#include <iostream>

using namespace cv;
using namespace std;

int main(  )
{
    Mat i=imread("home/ali/opencv/lena.png",1);
    namedWindow("a",WINDOW_FULLSCREEN);
    imshow("a",i);
    waitKey(0);
    return 0;
}

and this is my .pro file in Qt

QT += core
QT -= gui

CONFIG += c++11

TARGET = opencv
CONFIG += console
CONFIG -= app_bundle

TEMPLATE = app

INCLUDEPATH += /usr/local/include/opencv
LIBS += -L/usr/local/lib -lopencv_core -lopencv_imgcodecs -lopencv_highgui -lopencv_imgcodecs


SOURCES += main.cpp

this is what I receive:

OpenCV Error: Assertion failed (size.width>0 && size.height>0) in imshow, file /home/ali/Downloads/opencv/ line 304
terminate called after throwing an instance of 'cv::Exception'
  what():  /home/ali/Downloads/opencv/ error: (-215) size.width>0 && size.height>0 in function imshow

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^A

Using opencv3.2 ubuntu qt