title: Drawing a histogram in opencv python
body: <p>I want to detect lane departures of vehicles by processing front camera video.For that I want to select one pixel line of each frame horizontally and analyze how those pixels colors change. For that I want to draw histograms for R,G,B channels which has pixel number from left to right in x axis and the corresponding pixel value in y axis. Since I'm new to this area, I would like to know how can I draw this histogram for each frame in video by using opencv and python ? Thank you.</p>