How to crop an image in OpenCV using Python
It’s very simple. Use numpy slicing. import cv2 img = cv2.imread(“lenna.png”) crop_img = img[y:y+h, x:x+w] cv2.imshow(“cropped”, crop_img) cv2.waitKey(0)
opencv
OpenCV in Android Studio
The below steps for using Android OpenCV sdk in Android Studio. This is a simplified version of this(1) SO answer. Download latest OpenCV sdk for Android from OpenCV.org and decompress the zip file. Import OpenCV to Android Studio, From File -> New -> Import Module, choose sdk/java folder in the unzipped opencv archive. Update build.gradle … Read more
OpenCV C++/Obj-C: Detecting a sheet of paper / Square Detection
This is a recurring subject in Stackoverflow and since I was unable to find a relevant implementation I decided to accept the challenge. I made some modifications to the squares demo present in OpenCV and the resulting C++ code below is able to detect a sheet of paper in the image: void find_squares(Mat& image, vector<vector<Point> … Read more
Choosing the correct upper and lower HSV boundaries for color detection with`cv::inRange` (OpenCV)
Problem 1 : Different applications use different scales for HSV. For example gimp uses H = 0-360, S = 0-100 and V = 0-100. But OpenCV uses H: 0-179, S: 0-255, V: 0-255. Here i got a hue value of 22 in gimp. So I took half of it, 11, and defined range for that. … Read more
Video Streaming from IP Camera in Python Using OpenCV cv2.VideoCapture
You’re most likely getting that error due to an invalid stream link. Insert your stream link into VLC player to confirm it is working. Here’s a IP camera video streaming widget using OpenCV and cv2.VideoCapture.read(). This implementation uses threading for obtaining frames in a different thread since read() is a blocking operation. By putting this … Read more
Python OpenCV streaming from camera – multithreading, timestamps
Using threading to handle I/O heavy operations (such as reading frames from a webcam) is a classic programming model. Since accessing the webcam/camera using cv2.VideoCapture().read() is a blocking operation, our main program is stalled until the frame is read from the camera device and returned to our script. Essentially the idea is to spawn another … Read more
Java code to draw ellipse around face
x and y correspond to the top-left vertex of the rectangle. Given that the function you’ve specified takes only 4 parameters, I’m guessing it is an upright ellipse that you’re drawing. If you’ve found the code to draw rectangles around faces, then you should be able to extract (x,y) from there itself
How to read video stream as input in OpenCV python?
I agree with the comments above, more details are needed to know exactly how you are planning connect your camera. Here’s a working example for a webcam, notice that you should replace the input_id with your camera’s. You would work on frame for further processing. import cv2 def get_video(input_id): camera = cv2.VideoCapture(input_id) while True: okay, … Read more
Exception non gérée à 0x100e3cf2 dans shervinemami.exe : 0xC0000094: Integer division by zero
There is no integer division in that code, so there’s no way we can help. You might want to compile in debug mode and set the debugger to break on C++ Exceptions (you can do this in the Exception window in Visual Studio).
opencv c++ Edge detection to find edge that the top of it is white and the bottom is black
OpenCV can help you find edges using Canny Edge Detector You can refer for the implementation in this link OpenCV’s Canny Edge Detection in C++ Furthermore, I would like you to first do a bit of research on your own before actually asking for questions here.