如何使用来自python的请求从带有opencv的url打开图像 [英] How to open an image from an url with opencv using requests from python

问题描述

我正在尝试在 python 上使用 OpenCV 打开大量图像，因为我需要在后面使用它们.

I am trying to open a large list of images using OpenCV on python, because I need to work with them latter.

其实我可以用这样的枕头来实现这个目标:

Actually, I can achieve this goal with pillow like this:

url = r'https://i.imgur.com/DrjBucJ.png'
response = requests.get(url, stream=True).raw
guess = Image.open(response).resize(size)

我正在使用来自 python 的库 requests.

I am using the library requests from python.

response 看起来像这样:b'\x89PNG\r\n\x1a\n\x00\x00\x00\rIHDR\x00\x00\x01\xdb\...

如果我没记错的话，这些是来自 url 图像的像素值，对吗?

And if I am not wrong, those are the values of the pixels from the image of the url, correct?

我的问题是:我怎样才能用 OpenCV 做同样的事情?

My question is: how can I do the same with OpenCV?

我试过了:

resp = requests.get(url)
image = np.asarray(bytearray(resp.read()), dtype="uint8")
image = cv2.imdecode(image, cv2.IMREAD_COLOR)

我收到此错误:

image = np.asarray(bytearray(resp.read()), dtype="uint8")
AttributeError: 'Response' object has no attribute 'read'

我从这个网站得到了代码:https://www.pyimagesearch.com/2015/03/02/convert-url-to-image-with-python-and-opencv/

I got the code from this web: https://www.pyimagesearch.com/2015/03/02/convert-url-to-image-with-python-and-opencv/

推荐答案

你刚刚忘记了 requests.getstream=True 和 .raw>

You just forgot stream=True and .raw in requests.get

resp = requests.get(url, stream=True).raw

resp = requests.get(url, stream=True).raw

import cv2
import numpy as np
import requests

url = r'https://i.imgur.com/DrjBucJ.png'
resp = requests.get(url, stream=True).raw
image = np.asarray(bytearray(resp.read()), dtype="uint8")
image = cv2.imdecode(image, cv2.IMREAD_COLOR)

# for testing
cv2.imshow('image',image)
cv2.waitKey(0)
cv2.destroyAllWindows()

<小时>

回答你的问题

---

To answer your question

.raw 表示您希望以字节流的形式检索响应，而响应不会通过任何措施评估或转换(因此它不会解码 gzip 和 deflate 传输编码)，但是使用 .content gzip 和 deflate 传输-编码会自动为您解码.

.raw mean that you want to retrieve the response as a stream of bytes and the response will not evaluated or transformed by any measure (so it will not decode gzip and deflate transfer-encodings) but with .content The gzip and deflate transfer-encodings are automatically decoded for you.

在您的情况下，最好使用 .content 而不是 .raw

In your case it will be better to use .content over .raw

请求包文档中的以下说明

注意关于使用 Response.iter_content 与 Response.raw 的重要说明.Response.iter_content 将自动解码 gzip 和 deflate 传输编码.Response.raw 是一个原始字节流——它不会转换响应内容.如果您确实需要访问返回的字节，请使用 Response.raw.

Note An important note about using Response.iter_content versus Response.raw. Response.iter_content will automatically decode the gzip and deflate transfer-encodings. Response.raw is a raw stream of bytes – it does not transform the response content. If you really need access to the bytes as they were returned, use Response.raw.

参考:

https://2.python-requests.org/en/master/user/quickstart/#raw-response-content

https://2.python-requests.org/en/master/user/quickstart/#binary-response-content

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