How to convert Python numpy array to base64 output

Question

I basically need to do this but in Python instead of Javascript. I receive a base64 encoded string from a socketio connection, convert it to uint8 and work on it, then need to convert it to base64 string so I can send it back.

So, up to this point I've got this (I'm getting the data dictionary from the socketio server):

import pickle
import base64
from io import BytesIO
from PIL import Image

base64_image_string = data["image"]
image = Image.open(BytesIO(base64.b64decode(base64_image_string)))
img = np.array(image)

How do I reverse this process to get from img back to base64_image_string?

UPDATE:
I have solved this in the following manner (continuing from the code snippet above):

pil_img = Image.fromarray(img)
buff = BytesIO()
pil_img.save(buff, format="JPEG")
new_image_string = base64.b64encode(buff.getvalue()).decode("utf-8")

Somewhat confusingly, new_image_string is not identical to base64_image_string but the image rendered from new_image_string looks the same so I'm satisfied!

Answer 1

I believe since numpy.arrays support the buffer protocol, you just need the following:

processed_string = base64.b64encode(img)

So, for example:

>>> encoded = b"aGVsbG8sIHdvcmxk"
>>> img = np.frombuffer(base64.b64decode(encoded), np.uint8)
>>> img
array([104, 101, 108, 108, 111,  44,  32, 119, 111, 114, 108, 100], dtype=uint8)
>>> img.tobytes()
b'hello, world'
>>> base64.b64encode(img)
b'aGVsbG8sIHdvcmxk'
>>>