#!/usr/bin/env python3
# -*- coding: utf-8 -*-
# PIL指的是 pillow 库
from PIL import Image
import numpy as np

a = np.asarray(Image.open('./python.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('./pythonHD.jpg')