Teach you to use 20 lines of code to achieve the effect of hand drawing

This article is one of the actual combat projects of the numpy library. For specific knowledge points , please see the following link: From getting started to giving up: python data analysis series-numpy
. Before writing, please make sure you have configured the python environment and downloaded the numpy library.

The original picture is as follows:

This is an effect picture:

Observe the hand drawing before drawing, you can find that it has the following characteristics:

• The main color is black, white and gray
• Heavier border lines
• The same or similar colors tend to be white
• Slight light source effect
  The libraries that need to be used are:
• numpy
• 
  Since the code of PIL is relatively short, the blogger commented the main code as follows:

import numpy as np
from PIL import Image


baseImg = Image.open("./img/myimg2.jpg").convert("L")  # 这里放置你要手绘的图片原图
a = np.array(baseImg).astype("float")

depth = 8.
grad = np.gradient(a)  # 取图像灰度的梯度值

grad_x, grad_y = grad  # 模拟图像梯度值
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   # 光源俯视角度，弧度值
vec_az = np.pi/4.    # 官员的方位角度，弧度值
dx = np.cos(vec_el)*np.cos(vec_az)  # 光源对x轴的影响
dy = np.sin(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)                      # 限制

img = Image.fromarray(b.astype("uint8")) # 重构图像
img.save("./toImg/myImage1.jpg")         # 保存图像

Give it a try!