How to get response of an image in django api, after encoded it in base64?

Question

I am trying to make an django api, which accepts image from post method. After that, I change it to grayscale and then, I tried sending back that image as HttprResponse after encoded it into base64. (Actually, I don't know how to send base64 encoded string as reponse. I am new to python). Here's my code:

# import the necessary packages
from django.views.decorators.csrf import csrf_exempt
from django.http import JsonResponse, HttpResponse
import numpy as np
import urllib.request
import json
import cv2
import os
import base64

@csrf_exempt
def combine(request):

    # check to see if this is a post request
    if request.method == "POST":
        # check to see if an image was uploaded
        if request.FILES.get("image1", None) is not None:
            # grab the uploaded image
            image1 = _grab_image1(stream=request.FILES["image1"])
            # image2 = _grab_image2(stream=request.FILES["image2"])

            gray = cv2.cvtColor(image1, cv2.COLOR_BGR2GRAY)

            final = base64.b64encode(gray)

    # return a response
    return HttpResponse(final)


def _grab_image1(stream=None):
        if stream is not None:
            data = stream.read()

            image1 = np.asarray(bytearray(data), dtype="uint8")
            image1 = cv2.imdecode(image1, cv2.IMREAD_COLOR)

        # return the image1
            return image1

I am using postman to test.

And from HttpResponse I am getting a lot of strings as you can see in above image. I copied those strings and tried to decode it online to get the final image. To which I get no image:

So, how to get image(base64 encoded) in response django api.

Answer 1

You have to encode it as jpg (assuming your image is in JPG format) first then you can call final = base64.b64encode(gray) ont it! This is because cv2.cvtColor() will return <class 'numpy.ndarray'> numpy array which can't be encoded as base64 just directly!

retval, buffer_img= cv2.imencode('.jpg', gray)
final = base64.b64encode(buffer_img)

final contains now a valid base64 string for your image which can be easily returned back!