adaptive document image binarization
sauvola binarization python
sauvola binarization wiki
niblack thresholding opencvniblack
sauvola thresholding

The first is the threshold that was used and the second output is the thresholded image. This code compares the different simple thresholding types: import cv2Download and share free MATLAB code, including functions, models, apps, Sauvola binarization method is well suited for ill illuminated or stained