Reading image file (file storage object) using OpenCV

user_4724057 0
Viewed 22308

I am sending an image by curl to flask server, i am using this curl command

curl -F "file=@image.jpg" http://localhost:8000/home

and I am trying to read the file using OpenCV on the server side.

On the server side I handle the image by this code

@app.route('/home', methods=['POST'])
def home():
    data =request.files['file']
    img = cv.imread(data)
    fact_resp= model.predict(img)
    return jsonify(fact_resp)

I am getting this error-

img = cv.imread(data)
TypeError: expected string or Unicode object, FileStorage found

How do I read the file using OpenCV on the server side?

Thanks!

flask opencv curl image
4 Answers

After a bit of experimentation, I myself figured out a way to read the file using CV2. For this I first read the image using PIL.image method

This is my code,

@app.route('/home', methods=['POST'])
def home():
    data =request.files['file']
    img = Image.open(request.files['file'])
    img = np.array(img)
    img = cv2.resize(img,(224,224))
    img = cv2.cvtColor(np.array(img), cv2.COLOR_BGR2RGB)
    fact_resp= model.predict(img)
    return jsonify(fact_resp)

I wonder if there is any straight forward way to do this without using PIL.

user_47240570

So incase you want to do something like ,

file = request.files['file']
img = cv.imread(file)

then do it like this

import numpy as np
file = request.files['file']
file_bytes = np.fromfile(file, np.uint8)
file = cv.imdecode(file_bytes, cv.IMREAD_COLOR)

Now you don't need to do cv.imread() again, but can use this in the next line of codes.

This applies to OpenCV v3.x and onwards

user_109013000

Two-line solution, change grayscale to what you need

 file_bytes = numpy.fromfile(request.files['image'], numpy.uint8)
 # convert numpy array to image
 img = cv.imdecode(file_bytes, cv.IMREAD_GRAYSCALE)
user_10270330
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