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

Try thresholding the image like this. Make sure your src is in grayscale. This method will only retain the pixels which are between 150 and 255 intensity.

threshold(src, output, 150, 255, CV_THRESH_BINARY | CV_THRESH_OTSU);

You might want to invert the image as you are trying to negate the gray pixels. After the operation, invert it again to get your desired result.