在python中读取PNG的字节数
在python中读取PNG的字节数
提问于 2018-07-05 03:39:20
我想读取PNG的字节，并修改它们。我已经试过这个代码了：
import codecs
ed = input("Would you like to encode or decode?\n(e/d)> ")
image = input("What image would you like to use?\n> ")
if(ed == 'e'):
imagef = codecs.open(image, encoding = "hex")
imagel = imagef.read()
img = imagel.decode('hex')
print(img)但我得到以下错误：
Would you like to encode or decode?
(e/d)> e
What image would you like to use?
> i.png
Traceback (most recent call last):
File "main.py", line 7, in <module>
imagel = imagef.read()
File "/usr/local/Cellar/python/3.6.5/Frameworks/Python.framework/Versions/3.6/lib/python3.6/codecs.py", line 700, in read
return self.reader.read(size)
File "/usr/local/Cellar/python/3.6.5/Frameworks/Python.framework/Versions/3.6/lib/python3.6/codecs.py", line 503, in read
newchars, decodedbytes = self.decode(data, self.errors)
File "/usr/local/Cellar/python/3.6.5/Frameworks/Python.framework/Versions/3.6/lib/python3.6/encodings/hex_codec.py", line 25, in decode
return hex_decode(input, errors)
File "/usr/local/Cellar/python/3.6.5/Frameworks/Python.framework/Versions/3.6/lib/python3.6/encodings/hex_codec.py", line 19, in hex_decode
return (binascii.a2b_hex(input), len(input))
binascii.Error: Non-hexadecimal digit found我该怎么解决这个问题？
回答 1
Stack Overflow用户
发布于 2018-07-05 03:44:55
后退一步-你的假设是不正确的
png文件没有“十六进制内容”-它们有字节-“十六进制”不是你想的那样，它只是表示数字的另一种方式。
你的代码是不可修复的，因为它首先没有任何意义--没有什么需要解码的。
程序员使用十六进制是为了方便起见，因为每个十六进制数字可以表示4位，因此只需要两个十六进制数字来表示一个字节。然而，这只是一种表现。
编辑：
从注释中可以看出，您想要的是将二进制数据添加到文件的末尾：
message = 'Hello World!'
with open(image, 'ab') as f: # open the file for appending, binary mode
f.write(bytes(8)) # write 8 null bytes to the file
f.write(message.encode('utf-8')) # add the message, encoded to bytes
# by using the utf-8 encoding然后再读一遍消息：
with open(image, 'rb') as f: # open the file in read binary mode
data = f.read() # read the bytes from the file to a variable
pos = data.find(bytes(8)) # locate the 8 null bytes
message = data[pos + 8:].decode('utf-8') # decode the message页面原文内容由Stack Overflow提供。腾讯云小微IT领域专用引擎提供翻译支持
原文链接：
https://stackoverflow.com/questions/51179980
复制相关文章
相似问题