Unhandled exception at the end of thread - c++

Question

Hello right now i'm trying to use a thread to read some info about 2 images using OpenCV 2.3.1, while I can retrieve the sizes of the 2 images without a problem, an error occurs when I reach the end of the thread.
Unhandled exception at 0x00348A56 in OpenCvDemo.exe: An invalid parameter was passed to a function that considers invalid parameters fatal.
Since I can read the size of the images just fine I know they aren't empty or anything. In another test I detached the thread and put it to Sleep for 5 seconds, the main function executed fine and displayed the image, but once the thread woke up and reached the end it crashed the application and displayed the same error as above.
Sadly I need to use OpenCV 2.3.1 since this is just a test for a bigger application.
How can I solve this problem, or at least what is the cause of it?
#include "stdafx.h"
#include <windows.h>
#include <iostream>
#include <thread>
#include <opencv2/opencv.hpp>
void Loop(cv::Mat &image1, cv::Mat &image2) {
std::vector<uchar> buff1;
std::vector<uchar> buff2;
cv::imencode(".png", image1, buff1);
cv::imencode(".png", image2, buff2);
int imageSize1 = buff1.size();
int imageSize2 = buff2.size();
std::cout << "Size " << imageSize1 << "\n";
std::cout << "Size " << imageSize2 << "\n";
}
int main()
{
cv::Mat image1 = cv::imread("C:\\Users\\Cesar\\Pictures\\happyface.png", 1);
cv::Mat image2 = cv::imread("C:\\Users\\Cesar\\Pictures\\happyface.png", 1);
std::thread mythread(Loop, std::ref(image1), std::ref(image2));
mythread.join();
cv::imshow("name", image1);
cv::waitKey(0);
return 0;
}
The callstack
OpenCvDemo.exe!_invoke_watson(const wchar_t * expression, const wchar_t * function_name, const wchar_t * file_name, unsigned int line_number, unsigned int reserved) Line 224 C++
OpenCvDemo.exe!_invalid_parameter(const wchar_t * expression, const wchar_t * function_name, const wchar_t * file_name, unsigned int line_number, unsigned int reserved) Line 113 C++
[External Code]
OpenCvDemo.exe!Loop(cv::Mat & image1, cv::Mat & image2) Line 23 C++
[External Code]
OpenCvDemo.exe!invoke_thread_procedure(unsigned int(__stdcall*)(void *) procedure, void * const context) Line 92 C++
OpenCvDemo.exe!thread_start<unsigned int (__stdcall*)(void *)>(void * const parameter) Line 115 C++
[External Code]
[Frames below may be incorrect and/or missing, no symbols loaded for kernel32.dll]