Python資料分析與展示：圖像的手繪效果-5

圖像的RGB色彩模式

red green blue 0-255

圖像：由像素組成的二維矩陣，每個元素是一個rgb值

PIL pip install pillow

from PIL from Image      

簡單執行個體

為了看到圖檔效果，代碼拆開顯示

# -*- coding: utf-8 -*-

# @File    : image_demo.py
# @Date    : 2018-05-06

# pillow 5.1.0 -> 4.0.0

from PIL import Image
import numpy as np      

bigsea.jpg

# 讀取圖檔
img = Image.open("images/bigsea.jpg")
print(img)
# <PIL.JpegImagePlugin.JpegImageFile image mode=RGB size=1200x750 at 0x10105BE48>

# 轉為多元數組
a = np.array(img)
print(a.shape, a.dtype)
# (750, 1200, 3) uint8

b = [255, 255, 255 ] - a

# 轉為圖像
im = Image.fromarray(b.astype("uint8"))

# 儲存
im.save("images/bigsea1.jpg")      

bigsea1.jpg

# 彩色圖檔轉灰色
c = np.array(img.convert("L"))
print(c.shape, c.dtype)
# (750, 1200) uint8

d = 255 - c  # 取反

im2 = Image.fromarray(d.astype("uint8"))

im2.save("images/bigsea2.jpg")      

bigsea2.jpg

# 區間變換
e = (100/255)*c + 150  

im3 = Image.fromarray(e.astype("uint8"))

im3.save("images/bigsea3.jpg")      

bigsea3.jpg

# 像素平方
f = 255 * (c/255)*2 

im4 = Image.fromarray(f.astype("uint8"))

im4.save("images/bigsea4.jpg")      

bigsea4.jpg

圖像的手繪效果

# -*- coding: utf-8 -*-

# @File    : 圖像手繪效果.py
# @Date    : 2018-05-06

from PIL import Image
import numpy as np

a = np.asarray(Image.open('images/bigsea.jpg').convert('L')).astype('float')

depth = 10.  # (0-100)
grad = np.gradient(a)  # 取圖像灰階的梯度值
grad_x, grad_y = grad  # 分别取橫縱圖像梯度值
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  # 光源的俯視角度，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)  # 光源對x 軸的影響
dy = np.cos(vec_el) * np.sin(vec_az)  # 光源對y 軸的影響
dz = np.sin(vec_el)  # 光源對z 軸的影響

b = 255 * (dx * uni_x + dy * uni_y + dz * uni_z)  # 光源歸一化
b = b.clip(0, 255)

im = Image.fromarray(b.astype('uint8'))  # 重構圖像
im.save('images/beijingHD.jpg')
      

beijingHD.jpg