OpenCV | 易学教程

learning opencv3: 二：opencv整体的认识

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#include "opencv2/core/core_c.h" Old C data structures and arithmetic routines #include "opencv2/core/core.hpp" New C++ data structures and arithmetic routines #include "opencv2/flann/miniflann.hpp" Approximate nearest neighbor matching functions #include "opencv2/imgproc/imgproc_c.h" Old C image processing functions #include "opencv2/imgproc/imgproc.hpp" New C++ image processing functions #include "opencv2/video/photo.hpp" Algorithms specific to handling and restoring photographs #include "opencv2/video/video.hpp" Video tracking and background segmentation routines #include "opencv2

Webcam + Open CV Python | Black screen

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问题 I am using the code below, but I get a black image. Could you please help me rectify the error? import cv2 import numpy as np c = cv2.VideoCapture(0) while(1): _,f = c.read() cv2.imshow('e2',f) if cv2.waitKey(5)==27: break cv2.destroyAllWindows() 回答1: Update : See github.com/opencv/opencv/pull/11880 and linked conversations, only few backends support -1 as index. Although this is an old post, this answer can help people who are still facing the same problem. If you have a single webcam but it

Lanczos Interpolation in Python with 2D images

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问题 I try to rescale 2D images (greyscale). The image size is 256x256 and the desired output is 224x224. The pixel values range from 0 to 1300. I tried 2 approaches to rescale them with Lanczos Interpolation: First using PIL Image: import numpy as np from PIL import Image import cv2 array = np.random.randint(0, 1300, size=(10, 256, 256)) array[0] = Image.fromarray(array[0]).resize(size=(224, 224), resample=Image.LANCZOS) resulting in the error message: ValueError: image has wrong mode And then

IndexError: index 14708 is out of bounds for axis 0 with size 295

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问题 I'm trying to make object detection software with yolo and this error is popping and I am so lost please can anyone help me !! (the code not complete and sorry if there are any mistakes in this post cus I am new Stackoverflow).the tutorial is from here Traceback (most recent call last): File "d:/opencv/objdetect_yolo.py", line 66, in <module> findobj(output,img) File "d:/opencv/objdetect_yolo.py", line 33, in findobj cofidence = scores[classId] IndexError: index 14708 is out of bounds for

How to use OpenCV in React Native

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问题 All the similar questions I found were more or less unanswered. I want to detect edges and change the perspective of images and OpenCV seems to be the right choice. There is one guide that pops up on Google search which is very long and confusing. 回答1: I was finally able to use OpenCV with React Native. Since OpenCV isn't officially supported by React Native we will have to use Native Modules. Beware, you will have to use Java to use OpenCV functionalities. Download the OpenCV Android SDK.

How to use OpenCV in React Native

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Detecting trapezium, rhombus, square, quadrilateral, parallelogram by Opencv in Python

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问题 I've written a code like this to detect the shapes present in a png image. I get correct output for detecting a square and rectangle but for other shapes like Trapezium, rhombus, quadrilateral and parallelogram I am not able to detect it correctly. What is the correct code to detect these different types of polygon? _,thrash=cv2.threshold(imgGray,240,255,cv2.THRESH_BINARY) contours,_=cv2.findContours(thrash,cv2.RETR_TREE,cv2.CHAIN_APPROX_NONE) for contour in contours: approx=cv2.approxPolyDP

Python: Convert image from RGB to YDbDr color space

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问题 Trying to convert image from RGB color space to YDbDr color space according to the formula: Y = 0.299R + 0.587G + 0.114B Db = -0.45R - 0.883G +1.333B Dr = -1.333R + 1.116G + 0.217B With the following code I'm trying to show only Y channel which should be grayscale image but I keep getting image all in blue color: import numpy as np from PIL import Image import cv2 import matplotlib.pyplot as plt img = cv2.imread("./pics/Slike_modela/Test/Proba/1_Color.png") new_img = [] for row in img: new

OpenCV Segmentation of Largest contour in Breast Mammograms

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问题 This might be a bit too "general" question, but how do I perform GRAYSCALE image segmentation and keep the largest contour? I am trying to remove background noise (i.e. labels) from breast mammograms, but I am not successful. Here is the original image: First, I applied AGCWD algorithm (based on paper "Efficient Contrast Enhancement Using Adaptive Gamma Correction With Weighting Distribution") in order to get better contrast of the image pixels, like so: Afterwards, I tried executing

从零开始一起学习SLAM | 你好，点云

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本文提纲先热热身点云是啥你知道点云优缺点吗？点云库PCL：开发者的福音 PCL安装指北炒鸡简单的PCL实践留个作业再走先热热身小白：hi，师兄，好久不见师兄：师妹好，上周单应矩阵作业做了吗？小白：嗯，做了，这个单应矩阵真的挺有意思的。作业之外，我发现了一个新技能。。。师兄：什么技能？小白：我发现很多网上流传的图片都可以用上次我学过的单应矩阵实现，你看这张图，我第一次看到还以为是真的现在知道这不就是我们上节课讲的单应矩阵的变换吗？果然我在网上找到了原图现在我也会用OpenCV里的单应函数做这样的图了~ 师兄：哈哈，厉害了，会学以致用了。话说回来，今天有啥想问的？小白：嗯，最近在看点云相关的，师兄要不给我扫扫盲吧？师兄：这个我也有些了解，就把我知道的给你说说吧小白：yeah，师兄最棒！点云是啥师兄：那我就当你是个小白吧，从点云的定义说起。点云的英文是“point cloud”，点云的意思和它的名字一样，就是一堆点的集合，看起来像是一坨“云”。小白：一坨。。。师兄：哦，一坨不太文雅，应该是像一片“云”一样。上面只是一种形象的说法，其实点云在编程实现的时候是一种数据结构，用来表达多维空间中点的集合，这个多维空间一般对我们来说是三维空间。小白：哦，原来如此，也就是我们所在的 XYZ 空间咯师兄：对，因此点云在三维相关的领域内用的很多