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Tag: opencv

Reconstruct Image from patches/tiles in python

I have a task where I have tiled an Input image using the code: After that I calculated the sum of all tiles and sort them in ascending order. I’ll take the sum.sorted[-20] as a threshold and set all tiles below that threshold to 0 in order to neglect background. So far everything works fine. Now I need…

Why does saving an image with OpenCV result in a black image?

So, I want to create a 500×500 white image using python Numpy library, though I can easily do it in photoshop. The code below is valid and the image is white (because I saved the image using cv2.imsave function and later I opened it with windows photos viewer). But when I try to display it using the cv2.…

cv2.imshow() giving black screen

I’m converting a image (numpy array) into a string. Then I’m converting this string back to a numpy array of the original dimensions. Hence both the numpy arrays are equal- infact numpy.array_equals() also returns True for the arrays being equal. When I call cv2.imshow() on the original numpy arra…

opencv cascade.detectMultiScale creates error: (-215) !empty()

I am following this tutorial to understand haar features. While writing following code: getting following error: (Sachin is the image i downloaded from google, of size (237,237,3) and after converting gray it is (237,237) with min=23, max=210. I am using opencv 3.1.0 with python 3.6, installed using command c…

Display an image in a label without saving it

The following lines are in my script: from PyQt5 import QtGui, QtWidgets, QtCore from PyQt5.QtGui import QIcon, QPixmap from PyQt5.Widgets import * import cv2 def positioningCross(Dy, Dx, center, imgCross): if(center[1,0]>=center[0,0]): Dy2 = center[0,0] + np.absolute(Dy) else: Dy2 = center[1,0] + np.absol…

Access webcam using OpenCV (Python) in Docker?

I’m trying to use Docker for one of our projects which uses OpenCV to process webcam feed (Python). But I can’t seem to get access to the webcam within docker, here’s the code which I use to test webcam access: And here’s what I tried so far, All of these return False, what am I doing …