Comparing two images whether same or not

edit

This OpenCV tutorial shows how you can compare two images. PSNR and SSIM metrics are used, which are usually used for analysis of denoising algorithms. SSIM is constructed in a way to be close to the human perception.

Check out following links :

http://stackoverflow.com/questions/11173816/compare-2-16x16-pixel-images-similarity

http://stackoverflow.com/questions/23931/what-algorithm-to-compare-two-images

http://stackoverflow.com/questions/827680/where-can-i-find-code-for-comparing-two-images-and-determining-how-similar-they?lq=1

http://stackoverflow.com/questions/189943/how-can-i-quantify-difference-between-two-images

http://stackoverflow.com/questions/25977/how-can-i-measure-the-similarity-between-two-images

If you want to implement a "generic bitwise comparison" for cv::Mat you could write something like this:

bool cvMatEQ(const cv::Mat& data1, const cv::Mat& data2)
{
    bool success = true;
    // check if is multi dimensional
    if(data1.dims > 2 || data2.dims > 2)
    {
      if( data1.dims != data2.dims || data1.type() != data2.type() )
      {
        return false;
      }
      for(int32t dim = 0; dim < data1.dims; dim++){
        if(data1.size[dim] != data2.size[dim]){
          return false;
        }
      }
    }
    else
    {
      if(data1.size() != data2.size() || data1.channels() != data2.channels() || data1.type() != data2.type()){
        return false;
      }
    }
    int nrOfElements = data1.total()*data1.elemSize1();
    //bytewise comparison of data
    int cnt = 0;
    for(cnt = 0; cnt < nrOfElements && success; cnt++)
    {
      if(data1.data[cnt] != data2.data[cnt]){
        success = false;
      }
    }
    return success;
  }