Read from folder

edit

if your files are really numbered consecutively (and if those are in fact images), you could try via VideoCapture, like:

VideoCapture cap("file%d.png"); // think printf()
while(1) {
      Mat im;
      if (! cap.read(im))
           break;
}

in the long run, if you want your files to be lexically ordered, you have to take care to get the names right, like file00001.png and file2016-03-24.jpg