Wednesday, January 19, 2022
Numpy learning the third lesson - examples (hand-drawn processing of images)
Image processing is actually to deform the matrix.
1. Code :
from PIL import Image （pil库用于图像处理）
import numpy as np a = np.asarray(Image.open('./beijing.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('./beijingHD.jpg')效果：
2. Problems that arise:
problem analysis:
The currently allocated storage space is insufficient, and the computer terminates the running of the program prematurely.
Solution:
- Change float to float32 (change data type)
- Change the computer's virtual memory allocation (I didn't succeed)
3. Easter eggs
The conversion is like a ghost:
