对一张拍歪A4纸做投射矫正，使用了Canny算子、Hough变换等比较流行的技术，但重点在于排除无关直线的方法，做的还算比较完美，但是仍然存在不少的问题-A4 paper to do a shoot crooked projection correction, using the Canny operator, Hough transform technology more popular, but the focus is to exclude irrelevant straight line method, doing fairly perfect, but there are still many problems