OpenCV - Removal of noise in image

Question

I have an image here with a table.. In the column on the right the background is filled with noise

How to detect the areas with noise? I only want to apply some kind of

Answer 1

If you are very worried of removing pixels that could hurt your OCR detection. Without adding artefacts ea be as pure to the original as possible. Then you should create a blob filter. And delete any blobs that are smaller then n pixels or so.

Not going to write code, but i know this works great as i use this myself, though i dont use openCV (i wrote my own multithreaded blobfilter out of speed reasons). And sorry but i cannot share my code here. Just describing how to do it.