example6.py

from multiprocessing import Pool
import cv2

import sys
from functools import partial
from timeit import default_timer as timer


THRESH_METHOD = cv2.ADAPTIVE_THRESH_GAUSSIAN_C
INPUT_PATH = 'input/large_input/'
OUTPUT_PATH = 'output/large_output/'

n = 20
names = ['ship_%i_%i.jpg' % (i, j) for i in range(n) for j in range(n)]


def process_threshold(name, thresh_method):
    im = cv2.imread(INPUT_PATH + name)
    gray_im = cv2.cvtColor(im, cv2.COLOR_BGR2GRAY)
    thresh_im = cv2.adaptiveThreshold(gray_im, 255, thresh_method, cv2.THRESH_BINARY, 11, 2)

    cv2.imwrite(OUTPUT_PATH + name, thresh_im)


if __name__ == '__main__':

    for n_processes in range(1, 7):
        start = timer()

        with Pool(n_processes) as p:
            p.map(partial(process_threshold, thresh_method=THRESH_METHOD), names)

        print('Took %.4f seconds with %i process(es).' % (timer() - start, n_processes))
        
    print('Done.')