p 4000 y自学-把图片转化成字符画

此篇文章来自 实验楼python论坛，详细请转到https://www.shiyanlou.com/courses/370/labs/1191/document
一下几点有关说明如下：
1.PIL是python的图片处理包，argparse是命令行参数处理包
2.用parser可以指定参数，默认属性为括号内的值，这一点对于命令行来说比较方便from PIL import Image
import argparse
#命令行输入参数处理
parser = argparse.ArgumentParser()

parser.add_argument('file') #输入文件
parser.add_argument('-o', '--output') #输出文件
parser.add_argument('--width', type = int, default = 60) #输出字符画宽
parser.add_argument('--height', type = int, default = 40) #输出字符画高

#获取参数
args = parser.parse_args()

IMG = args.file
WIDTH = args.width
HEIGHT = args.height
OUTPUT = args.output

ascii_char = list("$@B%8&WM#*oahkbdpqwmZO0QLCJUYXzcvunxrjft/\|()1{}[]?-_+~<>i!lI;:,\"^`'. ")

# 将256灰度映射到70个字符上
def get_char(r,g,b,alpha = 256):
if alpha == 0:
return ' '
length = len(ascii_char)
gray = int(0.2126 * r + 0.7152 * g + 0.0722 * b)

unit = (256.0 + 1)/length
return ascii_char[int(gray/unit)]

if __name__ == '__main__':

im = Image.open(IMG)
im = im.resize((WIDTH,HEIGHT), Image.NEAREST)

txt = ""

for i in range(HEIGHT):
for j in range(WIDTH):
txt += get_char(*im.getpixel((j,i)))
txt += '\n'

print (txt)

#字符画输出到文件
if OUTPUT:
with open(OUTPUT,'w') as f:
f.write(txt)
else:
with open("output.txt",'w') as f:
f.write(txt)