import cv2
import numpy as np
from PIL import Image


def convert(filepath, savepath):
    gray= cv2.imread(filepath, cv2.IMREAD_GRAYSCALE)
    h, w = gray.shape[:2]

    out = np.zeros(gray.shape, np.uint8)

    for i in range(h):
        for j in range(w):
            pix = gray[i][j]
            if pix < 50:
                out[i][j] = 0
            elif pix < 200:
                out[i][j] = 0.25 * pix
            else:
                out[i][j] = 255

    out = np.around(out)
    out = out.astype(np.uint8)

    cv2.imwrite(savepath, out)


if __name__ == '__main__':
    filepath = 'pic/image1.jpg'
    savepath = 'pic/convert.jpg'
    convert(filepath, savepath)