CODEWITHSUNDEEP
pythonimagemqtt
godfreap
godfreap

Reputation: 373

Converting Images with Python

I'm having problems getting images to convert out of bytes/strings/etc. I can turn an image into a string, or a byte array, or use b64encode on it, but when I try decode/revert it back to an image, it never works. I've tried a lot of things, locally converting an image and then reconverting it, saving it under a different name. However, the resulting files will never actually show anything. (black on Linux, "can't display image" on windows)

My most basic b64encoding script is as follows:

import base64

def convert(image):
    f = open(image)
    data = f.read()
    f.close()
    string = base64.b64encode(data)
    convertit = base64.b64decode(string)

    t = open("Puppy2.jpg", "w+")
    t.write(convertit)
    t.close()


if __name__ == "__main__":
    convert("Puppy.jpg")

I've been stuck on this for a while. I'm sure it's a simple solution, but being new to Python, it's been a bit difficult trying to sort things out. If it helps with any insight, the end goal here is to transfer images over a network, possibly MQTT.

Any help is much appreciated. Thanks!

Edit** This is in Python 2.7. Edit 2** Wow, you guys move fast. What a great intro to the community - thanks a lot for the quick responses and super fast results!

Upvotes: 2

Views: 406

Answers (2)

Padraic Cunningham
Padraic Cunningham

Reputation: 180481

For python3, you need to open and write in binary mode:

def convert(image):
    f = open(image,"rb")
    data = f.read()
    f.close()
    string = base64.b64encode(data)
    convert = base64.b64decode(string)
    t = open("Puppy2.jpg", "wb")
    t.write(convert)
    t.close()

Using python 2 on linux, simply r and w should work fine. On windows you need to do the same as above.

from the docs:

On Windows, 'b' appended to the mode opens the file in binary mode, so there are also modes like 'rb', 'wb', and 'r+b'. Python on Windows makes a distinction between text and binary files; the end-of-line characters in text files are automatically altered slightly when data is read or written. This behind-the-scenes modification to file data is fine for ASCII text files, but it’ll corrupt binary data like that in JPEG or EXE files. Be very careful to use binary mode when reading and writing such files. On Unix, it doesn’t hurt to append a 'b' to the mode, so you can use it platform-independently for all binary files.

You can also write your code a little more succinctly by using with to open your files which will automatically close them for you:

from base64 import b64encode, b64decode

def convert(image):
    with open(image, "rb") as f, open("Puppy2.jpg", "wb") as t:
        conv = b64decode(b64encode(f.read()))
        t.write(conv)

Upvotes: 2

uGuest
uGuest

Reputation: 1

import base64

def convert(image):
    f = open(image)
    data = f.read()
    f.close()
    return data

if __name__ == "__main__":
    data = convert("Puppy2.jpg")
    string = base64.b64encode(data)
    convert = base64.b64decode(string)

    t = open("Puppy2.jpg", "w+")
    t.write(convert)
    t.close()

Upvotes: -1

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