All Questions
102 questions
0
votes
0
answers
44
views
Does the Intensity of color in OpenCV image matter?
Here is a simple code which puts a text value onto a black frame and displays it:
frame = np.zeros((50,200,3))
org=(0,45)
font=cv2.FONT_HERSHEY_SIMPLEX
fontScale=1
fontColor=(1,0,0) ##rgb
out_img =...
- 1,286
1
vote
2
answers
173
views
How to save the Fourier transform of an image such that I can modify it in an image editor?
I have a noisy image with a particular pattern and I want to remove the pattern. I save the FFT magnitude to a tiff image and the phases to a np.array text file.
I have this python code that computes ...
1
vote
1
answer
3k
views
How to convert a matplotlib figure to a cv2 image?
I would like to know how convert a matplotlib figure to a cv2 image, this is my python3 code:
import cv2
import matplotlib.pyplot as plt
# Generating matplotlib figure and save it as a png image
...
- 479
0
votes
1
answer
176
views
calculate the RMS intensity image with opencv
I would like to calculate the intensity of I(x,y)/Io(x,y).
First, I read my images using rawpy because I have .nef files (Nikon raw).
Then I use opencv to transform my images into grayscale and I ...
- 351
3
votes
2
answers
448
views
OpenCV pointPolygonTest() not working correctly
I want to split an image in 6 equal areas (as seen in the picture) and then I want to know to which area a point belongs to. I'm using pointPolygonTest() to check whether a point is inside a contour ...
- 53
0
votes
0
answers
67
views
Not able to see black and white image after threshold application
I am working on a project for detecting lines using threshold values in HLS image format. I wrote the following code for it. It is not giving any errors but the output I am getting is just a black ...
- 171
0
votes
1
answer
484
views
How can visualize 5 channel of image one by one?
I have a numpy array which dimension is (5, 3024, 4032) and data type float64. It is a 5 channel image and my question is: how can I visualize each channel one by one?
My input:
data_gt = np.load('...
-1
votes
1
answer
54
views
Make img's close range of RGB/HSV in particular value
share pic link: https://i.sstatic.net/hV9xH.jpg
If I have black gradient img , we know the RGB is (0 ~ 255) or HSV is (0 ~ 255)
How can I make close color range color together
such as ( 0 ~ 80), ( ...
user20396381
0
votes
3
answers
156
views
Unclear difference in displaying the same image by opencv and matplotlib [with example code & exported .npy file]
In continue to my previous question (that still not answered here)
Here is a simple code with some unsuccessful attempts and exported image.npy file that illustrates the problem:
'''
conda install ...
- 209
3
votes
0
answers
1k
views
ImportError: cannot import name 'get_versions' from 'matplotlib._version'
When doing my imports:
import cv2
from matplotlib import pyplot as plt
import numpy as np
import opencv_wrapper as cvw
I get:
ImportError Traceback (most recent call ...
- 2,263
4
votes
1
answer
1k
views
Calculating divergence and curl from optical flow and plotting it
I'm using flow = cv2.calcOpticalFlowFarneback() to calculate optical flow in a video and it gives me a numpy array with a shape of (height, width, 2) that contains the Fx and Fy values for each pixel (...
- 43
2
votes
2
answers
1k
views
Quantify longest axis and width of irregular shapes within a single image
Original question
I have about 80-100 images such as (A). Each image is composed of shapes that were filled with black color after marking the outline in ImageJ. I need to extract each individual ...
- 372
0
votes
0
answers
1k
views
Problems with importing some modules (here numpy) (ModuleNotFoundError: No module named 'numpy.core._multiarray_umath')
i would like to use opencv and tried to install the needed modules.
i need to install everything manually per donwload and then pip or install.
I am using Python 3.10.1 and Pip 21.2.4.
My project is ...
- 63
0
votes
0
answers
389
views
heatmap generated from numpy array gives inaccurate results
I am trying to generate a heatmap using bounding boxes coordinates to display the area where the detected object went to inside a room. To do that, I created a numpy array and used the coordinates to ...
- 899
1
vote
2
answers
425
views
Keep the original shape of the array as the image
I have some data. I visualize and then save it as image.
import cv2
import numpy as np
import matplotlib.pyplot as plt
data = np.array([
[1,2,0,1],
[0,1,2,1],
[0,0,2,1]])
fig, ax = plt.subplots()
ax....
- 392
0
votes
1
answer
707
views
Intersection area between a numpy array and a shapely polygon
I would like to calculate an area of the intersection of a shapely polygon, and a mask (numpy.array):
plt.plot(*building.exterior.xy, color='brown', linewidth=4)
plt.plot(*parcelle.exterior.xy, color='...
- 95
-3
votes
1
answer
188
views
Colour intensity is changing when stacking numpy image arrays
I am loading an image from here, which is saved as .nii.gz. The image opens fine (with a dimension of (497x497)), and when displayed using matplotlib, it shows with correct intensities, as shown below:...
- 506
1
vote
1
answer
627
views
Extract the values from graph
I want to extract data from plot.
Original plot:
But I can't obtain original values, in some places extracted line (green) above original data (black line), in some places it is below. I assume I ...
user16574886
1
vote
1
answer
563
views
ValueError: The truth value of an array with more than one element is ambiguous. Use a.any() or a.all() in plt.show() while plotting frame
I am trying to capture a video frame and then plot it using plt.imshow() but i am receiving this error.
vs = cv2.VideoCapture('../input/hard-hat-dataset/short_clip.mp`enter code here`4')
(grabbed, img)...
0
votes
0
answers
87
views
Change cv2.merge on matplotlib/numpy library command
I would like to change my code line "cv2.merge" to command from matplotlib/numpy library.
This is my only line in code from cv2 and I don't know how to get rid of it.
dataStretched have max ...
- 117
1
vote
1
answer
530
views
Recording a video from images and the respective annotation files
I have images stored in the another format in a folder. In a separate folder, I have text files that contain the coordinates of the rectangles which are supposed to be drawn over the image. I use the ...
- 19
1
vote
1
answer
1k
views
check if coordinates are overlapping using numpy, matplotlib
I need to check whether a square is overlapping with a defined polygon
Yes, it can be easily done using shapely as below
from shapely.geometry.polygon import Polygon
from shapely.geometry import box
...
- 131
0
votes
1
answer
851
views
OpenCV - Is there a way to detect objects of a specific color only in certain areas of an image using masking?
I am currently implementing something in OpenCV in which I want to detect objects of a specific color in certain areas. I know in order to pick up certain areas I can use adaptive threshold, however ...
- 29
1
vote
0
answers
168
views
Python3 cv2 and matplotlib import cause error
It seems when I try and use matplotlib and cv2 I get a weird QT error. I don't know what's causing it, here is how it looks:
QObject::moveToThread: Current thread (0x560dde045c50) is not the object's ...
- 160
2
votes
1
answer
121
views
Converting pixels colour creates noise
just a quick question:
I am loading a black and white image and then replacing the black and/or white pixels with other colors. The problem is when I visualize the edited image there are some black ...
0
votes
1
answer
5k
views
How to read images from our system folder to jupyter notebook python file
I have nine pictures inside a folder . I have to just read all the images in python for making a opencv model .
I want to read the all images at the same time in my .py notebook for do operations on ...
0
votes
1
answer
385
views
Plotting mean of n 2-D arrays
I'm trying to calculate the mean of histograms of several images from a folder and visualize it. Here is the approach I'm trying. I would calculate the histogram of each image with open cv, cv2....
-3
votes
2
answers
354
views
Conversion of numpy array to image [closed]
The array is a two-dimensional array populated with zeros and ones. How can I convert this array to a grayscale image such that there is a dot representing one in the array and an empty space where ...
0
votes
1
answer
4k
views
TypeError: Expected Ptr<cv::UMat> for argument '%s'
I have this error that I have not been able to solve on my own.
Can you tell me how to solve it please?
The problem is in this function:
import numpy as np
import cv2
import matplotlib.pyplot as plt
...
0
votes
2
answers
174
views
Numpy array of a png file is rotated in matplotlib.pyplot
I'm trying to scatter all white pixels of this gradient image in matplotlib.pyplot:
import numpy as np
from PIL import Image
import cv2
from matplotlib import pyplot
img = Image.open(
"/root/...
- 1
0
votes
1
answer
5k
views
How to draw a Heatmap in a image using the coordinates in Python OpenCV?
I've a huge list of Coordinates(x,y) of people walking in the streets and I like to design a heatmap using those Coordinates(x,y), i.e., it should look something like this. I want much hotter spot for ...
10
votes
7
answers
15k
views
Unable to send plot to http://127.0.0.1:63342
I am facing an error ie to send plot to a particular IP address using python, numpy and matplotlob. I am attaching snippet which I have tried till now.
Python
import numpy as np
import cv2
...
- 137
2
votes
1
answer
2k
views
How to plot frame per seconds (fps) over time using matplotlib when processing a video?
the below code calculates the number of processed frames per second for a video and display it on the output processed frame using opencv:
import cv2 as cv
import numpy as np
from collections import ...
- 563
1
vote
1
answer
1k
views
Find point coordinates on image
I've created random points and added a list these points double. Then I've drawn graphic and save as a image.
I'm able to draw a line from one point to another point with this code :
cv2.line(img=...
- 125
0
votes
1
answer
226
views
How to plot training data and training target for SVC
I'm trying to visualize my data, by plotting it, after loading images and extracting its keypoints. However, when i try to scatter it, before plotting, i get the error my x and y values should be the ...
user11597888
-1
votes
1
answer
63
views
matplotlib and opencv typerror imagedata cannot be converted to float
there i am getting an error
TypeError: Image data of dtype object cannot be converted to float
i can't figure out what the solution is my code is
import numpy as np
import cv2
import matplotlib....
- 503
2
votes
0
answers
50
views
How can I change the values of all the clusters obtained in an image to a new range that represents different levels of color intensity?
I'm doing some image analysis of samples of pseudomona. I'm using k-means clustering to obtain different levels of presence of the bacteria along the sample, as it changes tonality as it increases its ...
- 71
0
votes
1
answer
286
views
Finding circle function and center in Python
I have a data set (512 X 512), which is a 2D array. This is the figure I plot based on this data set.
Data looks like this:
[[239 247 214 ... 466 511 415]
[257 283 254 ... 460 474 474]
[219 251 ...
- 503
4
votes
1
answer
17k
views
Saving 16-bit image in opencv with cmap (cv::ColorMap only supports source images of type CV_8UC1 or CV_8UC3 in function 'operator()')
I'm trying to save/show a 16-bit numpy array (as image) in opencv with cmap, it doesn't work. On the other hand, it works smoothly in matplotlib.
My deep learning model gives a numpy array arr (<...
- 12.7k
1
vote
1
answer
2k
views
Gradient orientation with arctan2 results in flipped angles
I want to use plt.quiver to display arrows of the gradient of an array in the correct angle.
import numpy as np
import matplotlib.pyplot as plt
test_array = np.array([[ 0., 0., 0., 0., ...
- 1,272
1
vote
2
answers
904
views
updated:IndexError: index 0 is out of bounds for axis 0 with size 0?
I have a questions about the following codes:
I want to return 2 values in this function, one is orig_image which is fine, the other one is the cx,cx is the x-coordinate of the center of the biggest ...
- 29
1
vote
2
answers
1k
views
UnboundLocalError: local variable 'x1' referenced before assignment
import numpy as np
from PIL import ImageGrab
import cv2
import time
import pyautogui
import matplotlib.pyplot as plt
def make_coords(img,line_param):
slope,intercept=line_param
y1 = img....
- 29
0
votes
1
answer
3k
views
How to resize and translate a masked image over a background OpenCV and Python
By doing a bit of my own googling and following this tutorial I have created the python script below. It finds the most dominant (common) color in an image and replaces it with another "background" ...
- 411
2
votes
1
answer
612
views
Car plate recognition from video using python
enter image description hereI am running this code but it has given an error which I am trying to solve.
The given code is of car plate recognition from video written in python.
The given error:-
...
1
vote
2
answers
1k
views
Opencv unexpected output for Sobel operator
I am extracting the white stripes from this image but intrigued to see the output of basic Sobel operator in 'Lab' image. Although I am excited to see the black stripes as desired outcome, I am unable ...
- 503
0
votes
0
answers
115
views
know what are the pixel values through which a line passes over a grayscale image with the Bresenham line algorithm python
How to obtain pixel value of a gray scale image using the Bresenham line algorithm given a line at different angles as shown in this code fraction
I hope and you can help me
import cv2
import ...
- 1
1
vote
1
answer
420
views
Inverted pixel coordinates of segmentation mask
The following is an image of a segmentation mask (it appears yellow). Overlaid onto this mask are the pixels/coordinates of the very same segmentation mask (appears blue).
My question is: why are ...
- 1,139
4
votes
2
answers
4k
views
Calculate and plot segmentation mask pixels
I have the following image:
Below is a segmentation mask within this image:
From the image above, I attempted to calculate the non-zero pixel coordinates. That is, I tried to get all of the pixels ...
- 1,139
3
votes
1
answer
5k
views
How to convert my python code to run on GPU instead of CPU?
I was given a python code that takes in two images as input and uses the Gabor Filter to find the correlation of RGB of the two images and saves it in a csv file. So I need to execute the program ...
- 81
1
vote
1
answer
2k
views
How to get numpy.zeros() and (numpy.ones() * 255) to produce a black and white image respectively?
I am new to Python + OpenCV, so this might be a basic question for most of you, as I couldn't find a good/ satisfactory solution for this online.
So I am trying to create an Image by separately ...
- 948