How to detect noise in images : <p>How to detect noise in images?</p>

<p>I need to do some preprocessing before OCR and I need to detect if there are areas with noise? How to detect these areas? They are typically in rectangular areas</p>

<p>Below is an example. There are some noise in the last column to the right. I need the bounding boxes for all the areas with noise</p>

<p><a href="https://i.stack.imgur.com/wKPCp.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/wKPCp.png" alt="enter image description here"></a></p>
