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