如何使用OpenCV从URL读取gif(Python) [英] How to read gif from url using opencv (python)

问题描述

我可以使用cv2读取jpg文件

I can read jpg file using cv2 as

import cv2
import numpy as np
import urllib
url = r'http://www.mywebsite.com/abc.jpg'
req = urllib.request.urlopen(url)
arr = np.asarray(bytearray(req.read()), dtype=np.uint8)
img = cv2.imdecode(arr,-1)
cv2.imshow('abc',img)

但是，当我使用gif文件时，它会返回错误:

However, when I do it with gif file, it returns an error:

error: (-215) size.width>0 && size.height>0 in function cv::imshow

如何解决这个问题?

推荐答案

步骤:

1. 使用urllib从网络上读取gif
2. 使用imageio.mimread将gif加载到nump.ndarray.
3. 通过numpy或OpenCV更改频道顺序.
4. 使用OpenCV
进行其他图像处理

1. Use urllib to read the gif from web,
2. Use imageio.mimread to load the gif to nump.ndarray(s).
3. Change the channels orders by numpy or OpenCV.
4. Do other image-processing using OpenCV

代码示例:

import imageio
import urllib.request

url = "https://i.stack.imgur.com/lui1A.gif"
fname = "tmp.gif"

## Read the gif from the web, save to the disk
imdata = urllib.request.urlopen(url).read()
imbytes = bytearray(imdata)
open(fname,"wb+").write(imdata)

## Read the gif from disk to `RGB`s using `imageio.miread` 
gif = imageio.mimread(fname)
nums = len(gif)
print("Total {} frames in the gif!".format(nums))

# convert form RGB to BGR 
imgs = [cv2.cvtColor(img, cv2.COLOR_RGB2BGR) for img in gif]

## Display the gif
i = 0

while True:
    cv2.imshow("gif", imgs[i])
    if cv2.waitKey(100)&0xFF == 27:
        break
    i = (i+1)%nums
cv2.destroyAllWindows()

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注意. 我在另一个答案中使用了gif. 使用OpenCV进行视频稳定

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Note. I use the gif in my another answer. Video Stabilization with OpenCV

结果:

>>> Total 76 frames!

显示的gif框架之一:

One of the gif-frames displayed:

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