I am trying to return an image in fastAPI after comparing two images using Opencv.
Here's what I have done so far:
from fastapi import FastAPI , File, UploadFile
import numpy as np
from cv2 import *
import os
import base64
app = FastAPI(debug = True)
@app.post("/uploadfile/")
async def create_upload_file(file: UploadFile = File(...),file1: UploadFile = File(...)):
content = await file.read()
nparr = np.fromstring(content, np.uint8)
img = cv2.imdecode(nparr, cv2.IMREAD_COLOR)
content1 = await file1.read()
nparr1 = np.fromstring(content1, np.uint8)
img1 = cv2.imdecode(nparr1, cv2.IMREAD_COLOR)
akaze = cv2.AKAZE_create()
kpts1, desc1 = akaze.detectAndCompute(img, None)
kpts2, desc2 = akaze.detectAndCompute(img1, None)
matcher = cv2.DescriptorMatcher_create(cv2.DescriptorMatcher_BRUTEFORCE_HAMMING)
matches_1 = matcher.knnMatch(desc1, desc2, 2)
good_points = []
for m,n in matches_1:
if m.distance < 0.7 * n.distance:
good_points.append(m)
mat = (round(len(kpts2)/len(good_points),2))
return_img = cv2.processImage(img)
_, encoded_img = cv2.imencode('.PNG', return_img)
encoded_img = base64.b64encode(return_img)
return {"The similarity is": mat,'encoded_img': endcoded_img}
What am I doing wrong?
Yes you can return an image with FastAPI, it's actually so simple.
from fastapi import FastAPI
from fastapi.responses import FileResponse
some_file_path = "some_image.jpeg"
app = FastAPI()
@app.get("/")
async def main():
return FileResponse(some_file_path)
Make sure to install aiofiles with pip install aiofiles otherwise, you'll be getting an error like this:
AssertionError: 'aiofiles' must be installed to use FileResponse
If you have an image as bytes consider using StreamingResponse
from io import BytesIO
@app.post("/send_image")
async def send():
image = BytesIO()
img = # Do something here to create an image
img.save(image, format='JPEG', quality=85) # Save image to BytesIO
image.seek(0) # Return cursor to starting point
return StreamingResponse(image.read(), media_type="image/jpeg")
The solution can be found here. You are converting the Opencv Image before encoding it in the 3rd line.
return_img = cv2.processImage(img)
_, encoded_img = cv2.imencode('.PNG', return_img)
encoded_img = base64.b64encode(return_img)
return {"The similarity is": mat,'encoded_img': endcoded_img}
Replace return_img with encoded_img and everything should be working as expected.
return_img = cv2.processImage(img)
_, encoded_img = cv2.imencode('.PNG', return_img)
encoded_img = base64.b64encode(encoded_img)
return {"The similarity is": mat,'encoded_img': endcoded_img}
If you want to return the image only, then return the image itself with the correct encoding in the header see Return a Response Directly
If you need to also return other information with the image in the json, then see this SO question How do you put an image file in a json object? (note: the solutions are in javascript, but it's quite easy to adapt it for python)