Flask OpenCV 以字节为单位发送和接收图像

Question

我想在我的 Flask API 中以字节为单位发送和接收图像。我还想在图像旁边发送一些 json。我怎样才能实现这个目标？

以下是我当前的解决方案，不起作用

烧瓶：

    @app.route('/add_face', methods=['GET', 'POST'])
    def add_face():
    if request.method == 'POST':
        # print(request.json)
        nparr = np.fromstring(request.form['img'], np.uint8)
        print(request.form['img'])
        img = cv2.imdecode(nparr, cv2.IMREAD_COLOR)

        cv2.imshow("frame", img)
        cv2.waitKey(1)

    return "list of names & faces"

客户：

def save_encoding(img_file):
    URL = "http://localhost:5000/add_face"
    img = open(img_file, 'rb').read()

    response = requests.post(URL, data={"name":"obama", "img":str(img)})
    print(response.content)

产生错误：

cv2.imshow("frame", img)
cv2.error: OpenCV(3.4.3) /io/opencv/modules/highgui/src/window.cpp:356: error: (-215:Assertion failed) size.width>0 && size.height>0 in function 'imshow'

Answer 1

以 Base64 格式发送图像更容易，通过这样做，您可以摆脱发送/接收二进制数据的问题，因为您只需使用字符串。而且在网络方面也更方便。测试代码如下：服务器端：

from flask import Flask, render_template, request
import pandas as pd
import cv2
import numpy as np
import base64

app = Flask(__name__)



@app.route('/add_face', methods=['GET', 'POST'])
def add_face():
    if request.method == 'POST':
        #  read encoded image
        imageString = base64.b64decode(request.form['img'])

        #  convert binary data to numpy array
        nparr = np.fromstring(imageString, np.uint8)

        #  let opencv decode image to correct format
        img = cv2.imdecode(nparr, cv2.IMREAD_ANYCOLOR);
        cv2.imshow("frame", img)
        cv2.waitKey(0)

    return "list of names & faces"
if __name__ == '__main__':
    app.run(debug=True, port=5000)

客户端：

import requests
import base64

URL = "http://localhost:5000/add_face"

#  first, encode our image with base64
with open("block.png", "rb") as imageFile:
    img = base64.b64encode(imageFile.read())

response = requests.post(URL, data={"name":"obama", "img":str(img)})
print(response.content)

如果您确定输入图像，则可以使用 COLOR 而不是 ANYCOLOR。