I am working with Matplotlib color maps, and I also happen to be working with the Spyder IDE, which has an ipython console.
As you can see from the screen shot, the ipython console showed me a graphical representation of the color map object. This was unexpected and very helpful.
Normally I expect to see a string representation of an object, as you might see from the print() function call. Function calls to print() and repr() are shown, and they produce text, as is more typical.
I would like my own code to output this graphical representation when it is generating output. I have been poking through the matplotlib.colors.Colormap internals, and so far I haven't been able to figure out how. What is ipython doing? How can I do the same?
Thanks!
This rather seems like a ipython/jupyter feature. ipython detects the object and produces automatically a plot to preview the colormap.
Here using jupyter:
IPython looks if an object has a _repr_html_; if so, it calls it and displays the output as HTML. Here's an example (I ran this in Jupyter but it works the same as long as you're running IPython):
class MyCoolObject:
def _repr_html_(self):
return ("<h1>hello!</h1> <p>this is some html </p>"
"I can even put images:"
"<img src='https://upload.wikimedia.org/wikipedia"
"/commons/thumb/3/38/Jupyter_logo.svg"
"/44px-Jupyter_logo.svg.png'></img>")
MyCoolObject()
To add on to Eduardo's answer, from everything I've read adding a _repr_html_ method should make iPython display the object when you type it into the console. I also use spyder though, and could not get it to work the way I expected. This simple wrapper class should allow you to display any html:
class displayedHTML:
def __init__(self, html):
self.html = html
def _repr_html_(self):
return self.html
But as you can see it does not work for me, instead showing the (implicitly defined) __repr__ of the class.
In [2]: obj = displayedHTML("<h1>" + "hello world" + "</h1>")
In [3]: obj
Out[3]: <__main__.displayedHTML at 0x1e8cda8f0d0>
I was not able to find the reason why this does not work, but I found a workaround if you just want to display a matplotlib colormap in the console from code (like I did).
Since know the matplotlib object works correctly, we can just give it to the ipython display function:
from IPython.display import display #Included without import since IPython 5.4 and 6.1
viridis = matplotlib.cm.get_cmap('viridis')
display(viridis)
And for me this works...
not_allowed_to_insert_pictures_yet.jpg
Hope this helps!
I am using detecto model to visualize an image. So basically I am passing an image to this model and it will draw a boundary line accross the object and dislay the visualized image.
from keras.preprocessing.image import load_img
from keras.preprocessing.image import save_img
from keras.preprocessing.image import img_to_array
from detecto import core, utils, visualize
image = utils.read_image('retina_model/4.jpg')
model = core.Model()
labels, boxes, scores = model.predict_top(image)
img=visualize.show_labeled_image(image, boxes,)
Now, I am trying to convert this visualized image into Numpy array. I am using the below line for converting the image into numpy array :
img_array = img_to_array(img)
It is giving the errror :
Unsupported Image Shape
All I want is to display the visualized image which is the output of this model to my website. The plan is to convert the image into numpy array and then save the image by code using the below line :
save_img('image1.jpg', img_array)
So I was planning to download this visualized image (output of this model) so that I can display the downloaded image to my website. If there is some other way to do achieve this then please let me know.
Detecto's documentation says the utils.read_image() is already returning a NumPy array.
But you are passing the return of visualize.show_labeled_image() to Keras' img_to_array(img)
Looking at the Detecto source code of visualize.show_labeled_image(), it has no return type, so it is returning None by default. So I think your problem is you are not passing a valid image to img_to_array(img), but None.
I don't think the call to img_to_array(img) is needed, because you already have the image as a NumPy array. But note that according to Detecto's documentation, utils.read_image() is "Equivalent to using OpenCV’s cv2.imread function and converting from BGR to RGB format" . Make sure that's what you want.
you can visit the official github repo of detecto/visualize.pyto find out the show_labeled_image() function it uses matplotlib to plot the image with bounding boxes you can modify that code in your file to save the plot using plt.save_fig()
I am trying to do a basic colour conversion in python however I can't seem to get past the below error. I have re-installed python, opencv and tried on both python 3.4.3 (latest) and python 2.7 (which is on my Mac).
I installed opencv using python's package manager opencv-python.
Here is the code that fails:
frame = cv2.imread('frames/frame%d.tiff' % count)
frame_HSV= cv2.cvtColor(frame,cv2.COLOR_RGB2HSV)
This is the error message:
cv2.error: OpenCV(3.4.3) /Users/travis/build/skvark/opencv-python/opencv/modules/imgproc/src/color.cpp:181: error: (-215:Assertion failed) !_src.empty() in function 'cvtColor'
This error happened because the image didn't load properly. So you have a problem with the previous line cv2.imread. My suggestion is :
check if the image exists in the path you give
check if the count variable has a valid number
If anyone is experiencing this same problem when reading a frame from a webcam:
Verify if your webcam is being used on another task and close it. This wil solve the problem.
I spent some time with this error when I realized my camera was online in a google hangouts group. Also, Make sure your webcam drivers are up to date
I kept getting this error too:
Traceback (most recent call last):
File "face_detector.py", line 6, in <module>
gray_img=cv2.cvtColor(img, cv2.COLOR_BGR2GRAY)
cv2.error: OpenCV(4.1.0) C:\projects\opencv-python\opencv\modules\imgproc\src\color.cpp:182: error: (-215:Assertion failed) !_src.empty() in function 'cv::cvtColor
My cv2.cvtColor(...) was working fine with \photo.jpg but not with \news.jpg. For me, I finally realized that when working on Windows with python, those escape characters will get you every time!! So my "bad" photo was being escaped because of the file name beginning with "n". Python took the \n as an escape character and OpenCV couldn't find the file!
Solution:
Preface file names in Windows python with r"...\...\" as in
cv2.imread(r".\images\news.jpg")
If the path is correct and the name of the image is OK, but you are still getting the error
use:
from skimage import io
img = io.imread(file_path)
instead of:
cv2.imread(file_path)
The function imread loads an image from the specified file and returns
it. If the image cannot be read (because of missing file, improper permissions, unsupported or invalid format), the function returns an empty matrix ( Mat::data==NULL ).
check if the image exists in the path and verify the image extension (.jpg or .png)
Check whether its the jpg, png, bmp file that you are providing and write the extension accordingly.
Another thing which might be causing this is a 'weird' symbol in your file and directory names. All umlaut (äöå) and other (éóâ etc) characters should be removed from the file and folder names. I've had this same issue sometimes because of these characters.
Most probably there is an error in loading the image, try checking directory again.
Print the image to confirm if it actually loaded or not
In my case, the image was incorrectly named. Check if the image exists and try
import numpy as np
import cv2
img = cv2.imread('image.png', 0)
cv2.imshow('image', img)
I've been in same situation as well, and My case was because of the Korean letter in the path...
After I remove Korean letters from the folder name, it works.
OR put
[#-*- coding:utf-8 -*-]
(except [ ] at the edge)
or something like that in the first line to make python understand Korean or your language or etc.
then it will work even if there is some Koreans in the path in my case.
So the things is, it seems like there is something about path or the letter.
People who answered are saying similar things. Hope you guys solve it!
I had the same problem and it turned out that my image names included special characters (e.g. château.jpg), which could not bet handled by cv2.imread. My solution was to make a temporary copy of the file, renaming it e.g. temp.jpg, which could be loaded by cv2.imread without any problems.
Note: I did not check the performance of shutil.copy2 vice versa other options. So probably there is a better/faster solution to make a temporary copy.
import shutil, sys, os, dlib, glob, cv2
for f in glob.glob(os.path.join(myfolder_path, "*.jpg")):
shutil.copy2(f, myfolder_path + 'temp.jpg')
img = cv2.imread(myfolder_path + 'temp.jpg')
img = cv2.cvtColor(img, cv2.COLOR_BGR2RGB)
os.remove(myfolder_path + 'temp.jpg')
If there are only few files with special characters, renaming can also be done as an exeption, e.g.
for f in glob.glob(os.path.join(myfolder_path, "*.jpg")):
try:
img = cv2.imread(f)
img = cv2.cvtColor(img, cv2.COLOR_BGR2RGB)
except:
shutil.copy2(f, myfolder_path + 'temp.jpg')
img = cv2.imread(myfolder_path + 'temp.jpg')
img = cv2.cvtColor(img, cv2.COLOR_BGR2RGB)
os.remove(myfolder_path + 'temp.jpg')
In my case it was a permission issue. I had to:
chmod a+wrx the image,
then it worked.
must please see guys that the error is in the cv2.imread() .Give the right path of the image. and firstly, see if your system loads the image or not. this can be checked first by simple load of image using cv2.imread().
after that ,see this code for the face detection
import numpy as np
import cv2
cascPath = "/Users/mayurgupta/opt/anaconda3/lib/python3.7/site- packages/cv2/data/haarcascade_frontalface_default.xml"
eyePath = "/Users/mayurgupta/opt/anaconda3/lib/python3.7/site-packages/cv2/data/haarcascade_eye.xml"
smilePath = "/Users/mayurgupta/opt/anaconda3/lib/python3.7/site-packages/cv2/data/haarcascade_smile.xml"
face_cascade = cv2.CascadeClassifier(cascPath)
eye_cascade = cv2.CascadeClassifier(eyePath)
smile_cascade = cv2.CascadeClassifier(smilePath)
img = cv2.imread('WhatsApp Image 2020-04-04 at 8.43.18 PM.jpeg')
gray = cv2.cvtColor(img, cv2.COLOR_BGR2GRAY)
faces = face_cascade.detectMultiScale(gray, 1.3, 5)
for (x,y,w,h) in faces:
img = cv2.rectangle(img,(x,y),(x+w,y+h),(255,0,0),2)
roi_gray = gray[y:y+h, x:x+w]
roi_color = img[y:y+h, x:x+w]
eyes = eye_cascade.detectMultiScale(roi_gray)
for (ex,ey,ew,eh) in eyes:
cv2.rectangle(roi_color,(ex,ey),(ex+ew,ey+eh),(0,255,0),2)
cv2.imshow('img',img)
cv2.waitKey(0)
cv2.destroyAllWindows()
Here, cascPath ,eyePath ,smilePath should have the right actual path that's picked up from lib/python3.7/site-packages/cv2/data here this path should be to picked up the haarcascade files
Your code can't find the figure or the name of your figure named the by error message.
Solution:
import cv2
import numpy as np
import matplotlib.pyplot as plt
img=cv2.imread('哈哈.jpg')#solution:img=cv2.imread('haha.jpg')
print(img)
If anyone is experiencing this same problem when reading a frame from a webcam [with code similar to "frame = cv2.VideoCapture(0)"] and work in Jupyter Notebook, you may try:
ensure previously tried code is not running already and restart Jupyter Notebook kernel
SEPARATE code "frame = cv2.VideoCapture(0)" in separate cell on place where it is [previous code put in cell above, code under put to cell down]
then run all the code above cell where is "frame = cv2.VideoCapture(0)"
then try run next cell with its only code "frame = cv2.VideoCapture(0)" - AND - till you will continue in executing other cells - ENSURE - that ASTERIX on the left side of this particular cell DISAPEAR and command order number appear instead - only then continue
now you can try execute the rest of your code as your camera input should not be empty anymore :-)
After end, ensure you close all your program and restart kernel to prepare it for another run
As #shaked litbak , this error arised with my initial use with the ASCII-generator , as i naively thought i just had to add to the ./data directory , with its load automatically .
I had to append the --input option with the desired file path .
I checked my image file path and it was correct. I made sure there was no corrupt images.The problem was with my mac. It sometimes have a hidden file called .DS_Store which was saved together with the image file path. Therefore cv2 was having a problem with that file.So I solved the problem by deleting .DS_Store
I also encountered this type of error:
error: OpenCV(4.1.2) /io/opencv/modules/imgproc/src/color.cpp:182: error: (-215:Assertion failed) !_src.empty() in function 'cvtColor'
The solution was to load the image properly. Since the file mentioned was wrong, images were not loaded and hence it threw this error. You can check the path of the image or if uploading an image through colab or drive, make sure that the image is present in the drive.
I encounter the problem when I try to load the image from non-ASCII path.
If I simply use imread to load the image, I am only able to get None.
Here is my solution:
import cv2
import numpy as np
path = r'D:\map\上海地图\abc.png'
image = cv2.imdecode(np.fromfile(path, dtype=np.uint8), cv2.IMREAD_UNCHANGED)
Similar thing will happen when I save the image in a non-ASCII path. It will not be successfully saved without any warnings. And here is what I did.
import cv2
import numpy as np
path = r'D:\map\上海地图\abc.png'
cv2.imencode('.png', image)[1].tofile(path)
path = os.path.join(raw_folder, folder, file)
print('[DEBUG] path:', path)
img = cv2.imread(path) #read path Image
if img is None: # check if the image exists in the path you give
print('Wrong path:', path)
else: # It completes the steps
img = cv2.resize(img, dsize=(128,128))
pixels.append(img)
The solution os to ad './' before the name of image before reading it...
Just Try Degrading the OpenCV
in python Shell (in cmd)
>>> import cv2
>>> cv2.__version__
after Checking in cmd
pip uninstall opencv-python
after uninstalling the version of opencv install
pip install opencv-python==3.4.8.29
I'm using the IPython Notebook on Chrome. I've been trying to display several images in a loop, so that they display one after the other. After no luck with imshow() or set_data() (weird JSON non_serialisable errors, even on uint8 data - same happens when I use Image() on a Numpy array) I wrote the following helper function:
def fshow(im):
imsave('/test.png',im)
display(Image(filename='/test.png'))
which saves the image to a temporary file and then uses Image() to display it. It works beautifully - images pop up one after the other in the output cell, in real time, and I can intersperse them with Print statements if I want to.
But with monochrome images, they show up in the Jet colormap! So I used the following hack to save monochrome images as RGB images with identical colour channels...
def fshow(im):
sh=im.shape
sh=(im.shape[0],im.shape[1],3)
im2=zeros(sh)
im2[:,:,0]=im
im2[:,:,1]=im
im2[:,:,2]=im
imsave('/test.png',im2)
display(Image(filename='/test.png'))
This is, however, a bit of a hack. So, how can I change the colormap which Image uses to display monochrome images?
And as we're here, how do I get Image() to display a Numpy array without complaining that it can't be JSON serialised?