pip install pillow 

python3.4安装pillow失败，将python改为python2.7，安装成功

rm -f /usr/bin/python

ln -s /usr/bin/python2.7 /usr/bin/python

安装成功，可能会需要其他的一些库，yum或者pip安装就好了

使用pillow图片库  2.7

#!/usr/bin/python2.7
 
 from PIL import Image
 import argparse 
  
 arg = argparse.ArgumentParser()
 arg.add_argument("file")
 arg.add_argument("-o","--output")
 arg.add_argument("--width",type=int,default=80)
 arg.add_argument("--height",type=int,default=80)
  
 args = arg.parse_args()
  
 img = args.file
 width = args.width
 height = args.height
 output = args.output
  
 ascii_char = list("$@B%8&WM#*abcdefghijklmnopqrstuvwxyz/|()1[]{}?+-_=<>:;.,'. ")
 
 def get_char(r,b,g,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
 
     if output:
         with open(output,"w") as f:
             f.write(txt)
     else :
        with open("output.txt","w") as f:
             f.write(txt)