a qt+opencv program for converting a file picture to pdf
press Browse for choosing the picture, Run for corner detecting, and Save for saving to pdf.
Check the Colorful checkbox if colors are needed, or it will be only black and white.
After pressing Run, there will be a shrink picture with four blue spots marked. These dots will become the four corners of the outcoming pdf.
Press the blue dot once, it will turn to green. And then you can press the other location where you want the corner to be. After finishing
the modification, press Save.
Please make sure the background of the pictire is simple and without any other corners for the correctness of the corner finding.
