python颜色代码出错_cv2.imdecode颜色错误(python opencv)

The image looks like this:

I use this code:

import matplotlib.pyplot as plt

import numpy as np

import urllib

import cv2

url = 'http://skyservice.pha.jhu.edu/DR12/ImgCutout/getjpeg.aspx?ra=118.70299999999999&dec=45.721000000000004&width=10&height=10&scale=0.6'

def url_to_image(url):

resp = urllib.request.urlopen(url)

image = np.asarray(bytearray(resp.read()), dtype="uint8")

image = cv2.imdecode(image, cv2.IMREAD_COLOR)

return image

img = url_to_image(url)

plt.imshow(img)

And it displays this:

Where all colours are too blue. I have tried various possibilities to change cv2.IMREAD_COLOR with values found in the manual, on StackOverflow or elsewhere on the net, like -1, 0, 1, cv2.COLOR_BGR2RGB, ... but I haven't been able to get the right colours. I have tried cv2.COLOR_BGR2GRAY, it didn't even show in gray scales. I even tried this answer, but cv2.CV_LOAD_IMAGE_COLORdoesn't seem to exist anymore...

Is there a correct value of cv2.imdecode() flag, or a special colormap of plt.imshow(), which would give me the initial colours?

解决方案

Thanks to Mark Setchell, it now works. I quote him:

matplotlib requires RGB ordering whereas OpenCV (perversely) uses BGR

Therefore, the correct code is

def url_to_image(url):

resp = urllib.request.urlopen(url)

image = np.asarray(bytearray(resp.read()), dtype="uint8")

imageBGR = cv2.imdecode(image, cv2.IMREAD_COLOR)

imageRGB = cv2.cvtColor(imageBGR , cv2.COLOR_BGR2RGB)

return image

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