OpenCV error while converting image

Question

I am trying to import a picture of size (540,960) using matplotlib. This step is successfully executed. The result is stored in 'image' object (type ndarray).

# Do relevant imports
import matplotlib.pyplot as plt
import matplotlib.image as mpimg
import numpy as np
import cv2

# Read in and grayscale the image
image = mpimg.imread(r'C:\Temp\pic24_bw.jpg')
gray = cv2.cvtColor(image,cv2.COLOR_RGB2GRAY)

But when I try to convert the image into another color space (Gray), using cv2.cvtColor(). I face a error:

error: C:\projects\opencv-python\opencv\modules\imgproc\src\color.cpp:11111:        error: (-215) scn == 3 || scn == 4 in function cv::cvtColor

Please help. Strange thing is this code is running successfully in another citrix environment.

are you sure you're reading a 3 channel image? Looks like the image is already grayscale. — AHFromHogwarts
– AHFromHogwarts, Commented Jul 18 at 9:21

ambar mishra · Accepted Answer · 2019-10-12 13:55:37Z

1

This code works for me, load/read your image through cv2 itself and please do recheck your image path as it is the most common mistake, we does.

import numpy as np               
import matplotlib.pyplot as plt
import cv2
%matplotlib inline    
#reading the image 
image = cv2.imread('cat.jpg')
image = cv2.cvtColor(image,cv2.COLOR_BGR2GRAY)
#plotting the image
plt.imshow(image)

Hope this helps you out.

answered Oct 12, 2019 at 13:55

ambar mishra

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Comments

Tanay · Accepted Answer · 2018-01-20 12:20:49Z

0

I tried plt.imshow. The image is successfully loaded. It is shown in a RGB scale.

image = mpimg.imread(r'C:\Temp\pic24_bw.jpg') 
plt.imshow(image,cmap='gray')

answered Jan 20, 2018 at 12:20

Tanay

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1 Comment

Micka Over a year ago

maybe plt uses another channel ordering than opencv? Did you try cv2.imread to load the image?

Totoro doesn't feed AI anymore · Accepted Answer · 2019-10-13 11:06:39Z

0

This error message appears when the image could not be loaded, or it has an incorrect number of channels (cv2.COLOR_BGR2GRAY needs an image with 3 or 4 channels).

You have to use cv2.imread() instead of mpimg.imread()
If you still have errors, try print(image.shape). Most likely, the image does not have three channels.

You can also try viewing the image with:

cv2.imshow("Test", image)
cv2.waitKey()

answered Oct 13, 2019 at 11:06

Totoro doesn't feed AI anymore

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