如何从 fastapi 响应返回 PIL 图像文件列表？

Question

I have created an rest-api using fastapi, which takes a document (pdf) as input and return a jpeg image of it, I am using a library called docx2pdf for conversion.

from docx2pdf import convert_to    
from fastapi import FastAPI, File, UploadFile

app = FastAPI()

@app.post("/file/convert")
async def convert(doc: UploadFile = File(...)):
    if doc.filename.endswith(".pdf"):
        # convert pdf to image
        with tempfile.TemporaryDirectory() as path:
            doc_results = convert_from_bytes(
                doc.file.read(), output_folder=path, dpi=350, thread_count=4
            )

            print(doc_results)

        return doc_results if doc_results else None

This is the output of doc_results , basically a list of PIL image files

[<PIL.PpmImagePlugin.PpmImageFile image mode=RGB size=2975x3850 at 0x7F5AB4C9F9D0>, <PIL.PpmImagePlugin.PpmImageFile image mode=RGB size=2975x3850 at 0x7F5AB4C9FB80>]

If I run my current code, it is returning the doc_results as json output and I am not being able to load those images in another API.

How can I return image files without saving them to local storage? So, I can make a request to this api and get the response and work on the image directly.

Also, if you know any improvements I can make in the above code to speed up is also helpful.

Any help is appreciated.

Answer 1

You can not return that unless you convert it to something universal.

<PIL.PpmImagePlugin.PpmImageFile image mode=RGB size=2975x3850 at 0x7F5AB4C9F9D0

This basically says, You have an object of PIL at your memory here is the location for it .

The best thing you can do is, convert them to bytes and return an array of bytes.

---

You can create a function that takes a PIL image and returns the byte value from it.

import io

def get_bytes_value(image):
    img_byte_arr = io.BytesIO()
    img.save(img_byte_arr, format='JPEG')
    return img_byte_arr.getvalue()

Then you can use this function when returning the response

return [get_bytes_value(image) for image in doc_results] if doc_results else None