python - 如何将图像(ndarray对象)转换为图像对象以便可以JSON序列化？

Question

我是Python和编程世界的新手。我有一个将图像转换为 numpy 数组的代码。我想学习如何反转它，即将 numpy 数组转换为图像。

我有一个rest api代码，它从post方法获取图像，将其转换为numpy数组，进行一些处理并返回一些结果。但是，我正在尝试修改代码，以便我可以将两个图像作为 post 方法的输入，将其转换为 numpy 数组，将这些图像合并为一个并将最终图像作为 json 响应发送。

我已经成功修改了代码，因此它接受两个图像作为输入。稍后我将添加将两个图像合并为一个的代码。目前，我正在尝试将图像作为 json 响应发送。为此，我只是想按原样发送从 post 方法获得的图像。但我收到一个错误“‘ndarray’类型的对象不可 JSON 序列化”。所以，我想，我应该将 ndarray 对象(之前创建的)转换回图像，以便它可以被 json 序列化。如何做到这一点？

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


@csrf_exempt
def detect(request):
# initialize the data dictionary to be returned by the request
data = {"success":False}

# 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) and request.FILES.get("image2", None) is not None:
        # grab the uploaded image
        image1 = _grab_image1(stream=request.FILES["image1"])
        image2 = _grab_image2(stream=request.FILES["image2"])

    # otherwise, assume that a URL was passed in
    else:
        # grab the URL from the request
        url = request.POST.get("url", None)

        # if the URL is None, then return an error
        if url is None:
            data["error"] = "No URL provided."
            return JsonResponse(data)

        # load the image and convert
        image1 = _grab_image1(url=url)
        image2 = _grab_image2(url=url)

    # Code for combining two image

    data.update({"final1": image1,"final2": image2, "success": True})

# return a JSON response
return JsonResponse(data)

def _grab_image1(path=None, stream=None, url=None):
# if the path is not None, then load the image from disk
if path is not None:
    image1 = cv2.imread(path) #loads the image


# otherwise, the image does not reside on disk
else:   
    # if the URL is not None, then download the image
    if url is not None:
        resp = urllib.request.urlopen(url)
        data = resp.read()

    # if the stream is not None, then the image has been uploaded
    elif stream is not None:
        data = stream.read()

    # convert the image to a NumPy array and then read it into
    # OpenCV format
    image1 = np.asarray(bytearray(data), dtype="uint8")
    image1 = cv2.imdecode(image1, cv2.IMREAD_COLOR)

# return the image
return image1

def _grab_image2(path=None, stream=None, url=None):
# if the path is not None, then load the image from disk
if path is not None:
    image2 = cv2.imread(path) #loads the image


# otherwise, the image does not reside on disk
else:   
    # if the URL is not None, then download the image
    if url is not None:
        resp = urllib.request.urlopen(url)
        data = resp.read()

    # if the stream is not None, then the image has been uploaded
    elif stream is not None:
        data = stream.read()

    # convert the image to a NumPy array and then read it into
    # OpenCV format
    image2 = np.asarray(bytearray(data), dtype="uint8")
    image2 = cv2.imdecode(image2, cv2.IMREAD_COLOR)

# return the image
return image2

转换图像(ndarray对象)，以便它可以被json序列化。

Answer 1

我认为不可能以这种方式做你想做的事情......也许你可以尝试两件事:

1. 将其存储在服务器中的某个位置并序列化其 URL。
2. 对图像进行编码，将编码后的图像放入 JSON 中并稍后进行解码。你可以尝试使用base64 python 库。

如果选择第二个选项，只需像这样对 ndarray 进行编码:

coded_image = base64.b64encode(image)

解码:

decoded_image = base64.decodestring(coded_image)