Python数据分析与展示之图像的手绘效果实例分析学习笔记手札及代码实战

学习笔记手札及单元小结

图像的数组表示

以下代码请在Anaconda的IPython平台运行
PIL库的安装：
在命令行下的安装方法：pip install pillow

from PIL import Image   #Image是PIL库中代表一个图像的类（对象）

from PIL import Imageimport numpy as npim = array(Image.open("C:/01.jpg"))
---------------------------------------------------------------------------
NameError                                 Traceback (most recent call last)
<ipython-input-3-8a130c29210a> in <module>
----> 1 im = array(Image.open("C:/01.jpg"))NameError: name 'array' is not definedim = np.array(Image.open("C:/01.jpg"))print(im.shape,im.dtype)
(2448, 1836, 3) uint8 #图像是一个三维数组，维度分别是高度·宽度和像素RGB值

图像的变换

读入图像后，获得像素RGB值，修改后保存为新的文件

from PIL import Imageimport numpy as npa = np.array(Image.open("D:/01.jpg"))print(a.shape,a.dtype)
(2448, 1836, 3) uint8b = [255,255,255] -aim = Image.fromarray(b.astype('uint8'))im.save("D:/02.jpg")

from PIL import Imageimport numpy as npa = array(Image.open("D:/01.jpg").convert('L'))
---------------------------------------------------------------------------
NameError                                 Traceback (most recent call last)
<ipython-input-3-5e990d68fb86> in <module>
----> 1 a = array(Image.open("D:/01.jpg").convert('L'))NameError: name 'array' is not defineda = np.array(Image.open("D:/01.jpg").convert('L'))b = 255 - aim = Image.fromarray(b.astype('uint8'))im.save("D：/03.jpg")
---------------------------------------------------------------------------
FileNotFoundError                         Traceback (most recent call last)
<ipython-input-7-79fa9e4b0e79> in <module>
----> 1 im.save("D：/03.jpg")~\anaconda3\lib\site-packages\PIL\Image.py in save(self, fp, format, **params)2097                 fp = builtins.open(filename, "r+b")2098             else:
-> 2099                 fp = builtins.open(filename, "w+b")2100 2101         try:FileNotFoundError: [Errno 2] No such file or directory: 'D：/03.jpg'   #注意代码书写格式规范，这个是错误案例im.save("D:/03.jpg")

from PIL import Imageimport numpy as npa = np.array(Image.open("D:/01.jpg").convert('L'))c = (100/255)*a + 150 #区间变换im = Image.fromarray(c.astype('uint8'))im.save("D:/04.jpg")

from PIL import Imageimport numpy as npa = np.array(Image.open("D:/01.jpg").convert('L'))d = 255 * (a/255)**2  #像素平方im = Image.fromarray(d.astype('uint8'))im.save("D:/05.jpg")

"图像的手绘效果"实例分析

from PIL import Imageimport numpy as npa = np.asarray(Image.open('D:/01.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_y*depth/100.grad_y = grad_y*depth/100.A = np.sqrt(grad_x**2 + grad_y**2 + 1.)uni_x = grad_x/Auni_y = grad_y/Auni_z = 1./Avec_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('D:/HD.jpg')