How to use opencv extra modules?

OpenCV: What are good ways to use open CV/python to spot marks on a page?

• I am trying to check if a second hand book i'm planning to purchase has any page with coffee cup spots or marks or underlines etc. what should be my approach? I am able to capture the video stream of a book through my webcam/python/openCV. what should I do next?

• Answer:

  Assuming the marks are in some colour other than black or white and the text is in black and white,you should 1)First convert it into HSV color model using cvtColor. 2) To select a particular color ,give the range of Hue values you want to select inside inrange function. Maybe for saturation and value the whole range can be given. 3) The marks are returned as white color(255) in inrange function. By the way, why use open CV when you can simply spot the marks manually :) And prefer to ask program related questions in stackoverflow to get quicker answers.