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

I had already faced the same issue and got the best solution. Convert source image to grayscale image and apply fastNlMeanDenoising function and then apply threshold.

Like this -

fastNlMeansDenoising(gray,dst,3.0,21,7);
threshold(dst,finaldst,150,255,THRESH_BINARY);

ALSO use can adjust threshold accorsing to your background noise image. eg- threshold(dst,finaldst,200,255,THRESH_BINARY);

NOTE - If your column lines got removed...You can take a mask of column lines from source image and can apply to the denoised resulted image using BITWISE operations like AND,OR,XOR.