My aim is to segment screws and to find whether it is good or not. Segmentation part is over. Now I am finding lines inside the screw are good or not. To prove it, I need to find whether lines are perfectly parallel to each other. Secondly, I need to find the distance between lines. I used Line Segment Detector(LSD) to find lines in my image. It gave several lines. Now I want to prove whether lines in the screw are parallel are not. I had extracted slope of lines and I stored it in a integer variable. Now I want to know which line have which slope value. For example, I have slope value of 10, I want to draw line with slope 10 only. Can anyone help me to overcome this problem? Thanks in advance!