如何在Python3中使用OpenCV从文件缓冲区读取文件

Question

我正在尝试使用这个库。特别是以下三行代码：

    image_stream = io.BytesIO(image_bytes)
    frame = cv2.imread(image_stream)

我遇到了一个异常：

Traceback (most recent call last):
  File "/home/a/Pictures/pycharm-community-2018.3.2/helpers/pydev/pydevd.py", line 1741, in <module>
    main()
  File "/home/a/Pictures/pycharm-community-2018.3.2/helpers/pydev/pydevd.py", line 1735, in main
    globals = debugger.run(setup['file'], None, None, is_module)
  File "/home/a/Pictures/pycharm-community-2018.3.2/helpers/pydev/pydevd.py", line 1135, in run
    pydev_imports.execfile(file, globals, locals)  # execute the script
  File "/home/a/Pictures/pycharm-community-2018.3.2/helpers/pydev/_pydev_imps/_pydev_execfile.py", line 18, in execfile
    exec(compile(contents+"\n", file, 'exec'), glob, loc)
  File "/home/a/Documents/wiker/main.py", line 13, in <module>
    if __name__ == '__main__': main()
  File "/home/a/Documents/wiker/main.py", line 10, in main
    article['video'] = video.make_video_from_article(article)
  File "/home/a/Documents/wiker/video.py", line 15, in make_video_from_article
    frame = cv2.imread(image_stream)
TypeError: bad argument type for built-in operation

但它可以在真实文件上运行。这里有什么需要修复的地方。

- user10886181

---

如果您打印出 print(type(image_stream))，您会得到什么？ - Employee

<class '_io.BytesIO'> - user10886181

可能是 https://dev59.com/_1YN5IYBdhLWcg3w9MRJ 的重复问题。 - Employee

阅读文档。imread 的第一个参数需要是文件名，而不是流。它只能从文件中读取。如果你想要从内存中解码数据，你需要使用 imdecode。 - Dan Mašek

你的 image_bytes 是否已经编码？ - Ulrich Stern

我这样获取图像数据 image_content = get("https://" + image_url).content，需要引入模块 from requests import get。 - user10886181

Answer 1

这里有一个解决方案：

import io, requests, cv2, numpy as np

url = "https://images.pexels.com/photos/236047/pexels-photo-236047.jpeg"
img_stream = io.BytesIO(requests.get(url).content)
img = cv2.imdecode(np.frombuffer(img_stream.read(), np.uint8), 1)

cv2.imshow("img", img)
cv2.waitKey(0)

- Ulrich Stern

---

太棒了，谢谢！如果我想做相反的事情怎么办？从cv2转到io流？ - Rami.K

@Rami.K https://dev59.com/OmMl5IYBdhLWcg3w_bHj#64849668 - ch4rl1e97