pip install pillow
pip install numpy

# -*- coding: utf-8 -*-
from PIL import Image
from random import randint

old = Image.open(r"da.jpg")
new = Image.new('L', old.size, 255)
w, d = old.size
old = old.convert('L')
PEN_SIZE = 3
COLOR_DIFF = 7
LINE_LEN = 2

for i in range(PEN_SIZE + 1, w - PEN_SIZE - 1):
  for j in range(PEN_SIZE + 1, d - PEN_SIZE - 1):
    originalcolor = 255
    lcolor = sum([old.getpixel((i - r, j))
           for r in range(PEN_SIZE)]) // PEN_SIZE
    rcolor = sum([old.getpixel((i + r, j))
           for r in range(PEN_SIZE)]) // PEN_SIZE
    if abs(lcolor - rcolor) > COLOR_DIFF:
      originalcolor -= (255 - old.getpixel((i, j))) // 4
      for p in range(-LINE_LEN + randint(-1, 1), LINE_LEN + randint(-1, 1)):
        new.putpixel((i, j + p), originalcolor)

    ucolor = sum([old.getpixel((i, j - r))
           for r in range(PEN_SIZE)]) // PEN_SIZE
    dcolor = sum([old.getpixel((i, j + r))
           for r in range(PEN_SIZE)]) // PEN_SIZE
    if abs(ucolor - dcolor) > COLOR_DIFF:
      originalcolor -= (255 - old.getpixel((i, j))) // 4
      for p in range(-LINE_LEN + randint(-1, 1), LINE_LEN + randint(-1, 1)):
        new.putpixel((i + p, j), originalcolor)

    lucolor = sum([old.getpixel((i - r, j - r))
            for r in range(PEN_SIZE)]) // PEN_SIZE
    rdcolor = sum([old.getpixel((i + r, j + r))
            for r in range(PEN_SIZE)]) // PEN_SIZE
    if abs(lucolor - rdcolor) > COLOR_DIFF:
      originalcolor -= (255 - old.getpixel((i, j))) // 4
      for p in range(-LINE_LEN + randint(-1, 1), LINE_LEN + randint(-1, 1)):
        new.putpixel((i - p, j + p), originalcolor)

    rucolor = sum([old.getpixel((i + r, j - r))
            for r in range(PEN_SIZE)]) // PEN_SIZE
    ldcolor = sum([old.getpixel((i - r, j + r))
            for r in range(PEN_SIZE)]) // PEN_SIZE
    if abs(rucolor - ldcolor) > COLOR_DIFF:
      originalcolor -= (255 - old.getpixel((i, j))) // 4
      for p in range(-LINE_LEN + randint(-1, 1), LINE_LEN + randint(-1, 1)):
        new.putpixel((i + p, j + p), originalcolor)

new.save(r"pencil_drawing.jpg")

from PIL import Image
import numpy as np

a = np.asarray(Image.open('牛.jpg').convert('L')).astype('float')
depth = 10. # (0-100)
grad = np.gradient(a) # 取图像灰度的梯度值
grad_x, grad_y = grad # 分别取横纵图像梯度值
grad_x = grad_x * depth / 100.
grad_y = grad_y * depth / 100.
A = np.sqrt(grad_x ** 2 + grad_y ** 2 + 1.)
uni_x = grad_x / A
uni_y = grad_y / A
uni_z = 1. / A
vec_el = np.pi / 2.2 # 光源的俯视角度，弧度值
vec_az = np.pi / 4. # 光源的方位角度，弧度值
dx = np.cos(vec_el) * np.cos(vec_az) # 光源对x 轴的影响
dy = np.cos(vec_el) * np.sin(vec_az) # 光源对y 轴的影响
dz = np.sin(vec_el) # 光源对z 轴的影响
b = 255 * (dx * uni_x + dy * uni_y + dz * uni_z) # 光源归一化
b = b.clip(0, 255)
im = Image.fromarray(b.astype('uint8')) # 重构图像
im.save('new.jpg')