I imported all the required libraries and tried to do a simple image reconginition program with opencv but the error cv2 not defined shows up but as it is visible from the first cell that open cv is installed and no import errors are shown as I have already done the !apt updates and the version I have is 3.4.0. Any help on the program attached below would be appreciated. Thanks in advance.
First, I recommend you to get yourself familiar with Jupyter notebooks and how they work. Then, the first problem you had it was because you were trying to run a cell that uses cv2 without running the import cv2 before. The second problem you are facing is because you cannot use cv2.imshow(...), since it requires an X server which is not available. Below, you can see an MCVE in which you can upload an image, use OpenCV to read and change it, and display images:
import cv2
import matplotlib.pyplot as plt
# %matplotlib inline
from google.colab import files
uploaded = files.upload()
img = cv2.imread('lenna.png')
gray_img = cv2.cvtColor(img, cv2.COLOR_BGR2GRAY)
fig, ax = plt.subplots(ncols=2)
ax[0].imshow(img[..., ::-1]) # BGR to RGB
ax[0].set_title('Original image')
ax[1].imshow(gray_img, cmap=plt.cm.gray)
ax[1].set_title('Grayscale image')
plt.show()
If you run on Google Colab, it will look like this:
You can use this solution if you're using google colab:
from google.colab.patches import cv2_imshow
image = cv2.imread('image.png')
cv2_imshow( image)
cv2.waitKey(0)
cv2.destroyAllWindows()
Related
When I use
cv2.imshow(img)
colab throws a DisabledFunctionError (https://github.com/jupyter/notebook/issues/3935).
Using cv2_imshow(img) I am getting another error, AttributeError: 'NoneType' object has no attribute 'clip').
How can I solve this?
Using cv2.imshow(img) in Google Colab returns this output:
DisabledFunctionError: cv2.imshow() is disabled in Colab, because it causes Jupyter sessions
to crash; see https://github.com/jupyter/notebook/issues/3935.
As a substitution, consider using
from google.colab.patches import cv2_imshow
Accordingly, you can simply use:
from google.colab.patches import cv2_imshow
import matplotlib.pyplot as plt
img = "yourImage.png"
img = cv2.imread(img) # reads image
plt.imshow(img)
Try this:
from google.colab.patches import cv2_imshow
cv2_imshow(img)
One can also display images in the markdown/Text cell in Colab. Create a Text cell and then you will have a top bar with icons. Select the image icon corresponding to “Insert images” and then choose from you local machine the image.
For a few hours now, I've been trying to figure out how to view an image I imported with pillow. So far, I got rid of all errors, but it just shows the exact filename of the photo, the image isn't showing up, please help me fix this.
This is what I have so far:
from PIL import Image
img = Image.open("image.jpg")
print(img)
From the docs the function to show an image is
Image.show(title=None, command=None)
So to display an image you can do
from PIL import Image
img = Image.open("image.jpg")
img.show()
Sir Please try this code
from PIL import Image
import matplotlib.pyplot as plt
%matplotlib inline
a=Image.open("F:\\FYP DATASET\\images\\train\\10_left.jpeg")
a
try by removing print statement and adding matplotlib library.
Purpose of %Matplotlib inline in Python:
By just writing variable without print statement will display the image in notebook and by img.show() It will display image in Photo Viewer (Windows photo viwer) etc depends on what you are using.
from PIL import Image
img = Image.open("man.png")
img.show()
I am working on a project which requires functions from OpenCV to plot images.
I am trying to display image using the below code in Google Colab. But nothing shows up in the output. Can anybody help me with this?
%pylab notebook
import cv2
testim = imread('butterfly.jpg')
figure()
imshow(testim)
plt.show()
Screenshot:
Link to my Colab Notebook
Google colab crashes if you try to display image using cv2.imshow() instead import from google.colab.patches import cv2_imshow and display using cv2_imshow(<image>)
The cv2.imshow() and cv.imshow() functions from the opencv-python package are incompatible with Jupyter notebook; see https://github.com/jupyter/notebook/issues/3935.
As a replacement, you can use the following function:
from google.colab.patches import cv2_imshow
For example, here we download and display a PNG image of the Colab logo:
!curl -o logo.png https://colab.research.google.com/img/colab_favicon_256px.png
import cv2
img = cv2.imread('logo.png', cv2.IMREAD_UNCHANGED)
cv2_imshow(img)
Credits: Code Snippets in Google Colab
Found one workaround. We can use %matplotlib inline in the code to use imshow. Used as example here in In[28] - link
imshow requires an X server, which isn't available in a web browser.
Instead, use the IPython.display.Image library. Here's an example:
https://colab.research.google.com/drive/1jWHKR6rhhyZtUulttBD6Pxd_AJhgtVaV
cv2.imshow()
does not work well in colab, you can use matplotlib for displaying.
import matplotlib.image as mpimg
from matplotlib.pyplot import imshow
%matplotlib inline
testim = mpimg.imread('butterfly.jpg')
imshow(testim)
or you can do colab's own cv2_imshow version
from google.colab.patches import cv2_imshow
cv2_imshow('butterfly.jpg')
Instead of using cv2.imshow() try this:
Change the import to from google.colab.patches import cv2_imshow
Replace cv2.imshow() to cv2_imshow()
I tried it and it worked for me.
I am also facing a same issue in google colab.
We can use cv2_imshow() instead of (cv2.imshow or cv.imshow):
#We must import first line of code
**#working module**
from google.colab.patches import cv2_imshow
import cv2 as cv
#Replace cv2.imshow() to cv2_imshow()
img = cv.imread('python.jpg') #mentioning a path of an image
cv2_imshow(img)
while we are using our local machine to visble any image then we use this code cv.imshow(), but when it comes to google colab we should switch to alternative code cv2_imshow()
import os
import numpy as np
import matplotlib.pyplot as plt
import cv2
import pandas as pd
import matplotlib.image as mpimg
from google.colab.patches import cv2_imshow
cv2_imshowcv21_image =cv2.imread("apple.jpg")
scale_percent = 20 # percent of original size
width = int(cv21_image.shape[1] * scale_percent / 100)
height = int(cv21_image.shape[0] * scale_percent / 100)
dim = (width, height)
resized=cv2.resize(cv21_image,dim)
cv2_imshow(resized)
cv2.waitKey(0)
The modified code do the process.
I am trying to read a png image in python. The imread function in scipy is being deprecated and they recommend using imageio library.
However, I am would rather restrict my usage of external libraries to scipy, numpy and matplotlib libraries. Thus, using imageio or scikit image is not a good option for me.
Are there any methods in python or scipy, numpy or matplotlib to read images, which are not being deprecated?
With matplotlib you can use (as shown in the matplotlib documentation)
import matplotlib.pyplot as plt
import matplotlib.image as mpimg
img=mpimg.imread('image_name.png')
And plot the image if you want
imgplot = plt.imshow(img)
You can also use Pillow like this:
from PIL import Image
image = Image.open("image_path.jpg")
image.show()
import matplotlib.pyplot as plt
image = plt.imread('images/my_image4.jpg')
plt.imshow(image)
Using 'matplotlib.pyplot.imread' is recommended by warning messages in jupyter.
If you just want to read an image in Python using the specified
libraries only, I will go with matplotlib
In matplotlib :
import matplotlib.image
read_img = matplotlib.image.imread('your_image.png')
For the better answer, you can use these lines of code.
Here is the example maybe help you :
import cv2
image = cv2.imread('/home/pictures/1.jpg')
plt.imshow(image)
plt.show()
In imread() you can pass the directory .so you can also use str() and + to combine dynamic directories and fixed directory like this:
path = '/home/pictures/'
for i in range(2) :
image = cv2.imread(str(path)+'1.jpg')
plt.imshow(image)
plt.show()
Both are the same.
From documentation:
Matplotlib can only read PNGs natively. Further image formats are supported via the optional dependency on Pillow.
So in case of PNG we may use plt.imread(). In other cases it's probably better to use Pillow directly.
you can try to use cv2 like this
import cv2
image= cv2.imread('image page')
cv2.imshow('image', image)
cv2.waitKey(0)
cv2.destroyAllWindows()
I read all answers but I think one of the best method is using openCV library.
import cv2
img = cv2.imread('your_image.png',0)
and for displaying the image, use the following code :
from matplotlib import pyplot as plt
plt.imshow(img, cmap = 'gray', interpolation = 'bicubic')
plt.xticks([]), plt.yticks([]) # to hide tick values on X and Y axis
plt.show()
Easy way
from IPython.display import Image
Image(filename ="Covid.jpg" size )
I am trying to read and display an image in Python OpenCV.
Executing the following code:
import cv2
import numpy as np
import matplotlib.pyplot as plt
img = cv2.imread('dumb.jpg', cv2.IMREAD_GRAYSCALE)
cv2.imshow('image',img)
cv2.waitKey(0)
cv2.destroyAllWindows()
Results in the following error:
cv2.error:
C:\build\master_winpack-bindings-win64-vc14-static\opencv\modules\highgui\src\window.cpp:325: error: (-215) size.width>0 && size.height>0 in function cv::imshow
How to solve this?
NOTE: I have all the prerequisites needed to execute this (python 2.7, opencv 3.3
matplotlib, numpy)
If you are trying to display OpenCV image using matplotlib, use the code below.
import numpy as np
import cv2
import matplotlib.pyplot as plt
%matplotlib inline # if you are running this code in Jupyter notebook
# reads image 'opencv-logo.png' as grayscale
img = cv2.imread('/path_to_image/opencv-logo.png', 0)
plt.imshow(img, cmap='gray')
there is a tutorial on http://docs.opencv.org/3.1.0/dc/d2e/tutorial_py_image_display.html
import numpy as np
import cv2
# Load an color image in grayscale
img = cv2.imread('/path_to_image/messi5.jpg',0)
# show image
cv2.imshow('image',img)
cv2.waitKey(0)
cv2.destroyAllWindows()
use an absolute path to the image then you have no path problems
https://en.wikipedia.org/wiki/Path_(computing)#Absolute_and_relative_paths
OpenCV Error: (-215)size.width>0 && size.height>0 in function imshow
I have written a short post to learn image reading with OpenCV in Python. You can see the below code snippet with the description.
import cv2 #Import openCV
import sys #import Sys. Sys will be used for reading from the command line. We give Image name parameter with extension when we will run python script
#Read the image. The first Command line argument is the image
image = cv2.imread(sys.argv[1]) #The function to read from an image into OpenCv is imread()
#imshow() is the function that displays the image on the screen.
#The first value is the title of the window, the second is the image file we have previously read.
cv2.imshow("OpenCV Image Reading", image)
cv2.waitKey(0) #is required so that the image doesn’t close immediately. It will Wait for a key press before closing the image.
To read an image with OpenCV you have to use the following synthax. If it doesn't work, there is a problem with the installation.
import cv2
image = cv2.imread('path_of_the_image.png')
cv2.imshow('img', image)
cv2.waitKey(0)
You didn't post the error it gives..
EDIT: I don't understand the negative points...for what ??
The reason for this error message is that cv2.imread() was unable to find the image where it was looking for the image. This should work if you add the full path to the image, like
img = cv2.imread('/home/foo/images/dumb.jpg',cv2.IMREAD_GRAYSCALE)
import cv2
import matplotlib.pyplot as plt
%matplotlib inline
# Hide grid lines
fig, ax = plt.subplots(figsize=(10,10))
ax.grid(False)
im=cv2.imread('./my_images.jpg')
plt.imshow(cv2.cvtColor(im, cv2.COLOR_BGR2RGB))
plt.show()
It use cv2.COLOR_BGR2RGB because it convert default settings of OpenCV which using BGR to RGB format
Use 0 rather than cv2.IMREAD_GRAYSCALE and I would hard code the location of the file rather than refer to it like that for example if it was on the C drive put 'C:\\Filename.jpg'
Try this one :
import cv2 as cv #openCV-3.4.1
import numpy as np
import matplotlib.pyplot as plt
img = cv.imread('image path and name .file type ',0)
cv.imshow('img',img)
cv.waitKey(0)
cv.destroyAllWindows()
It looks like your code is fine. The problem seems to be in the dimension of image that is being provided in the parameters. The error code says: size > 0 && width > 0. This condition is not meeting properly. Either dimension size or width is less than zero. You may want to check any other image and try with that.