I am really new to opencv. How can I remove the noise in the background without losing info?
https://i.stack.imgur.com/LQ3W3.jpg
I started with this: https://i.stack.imgur.com/YHtN6.jpg, and Otsu thresholded it. I've tried erosion, dilation, bilateral filtering. My goal is to get a rectangle on the borders so I can perspective transform the thresholded picture, but it has trouble finding contours. Or maybe is there a different and better approach?