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Questions tagged [opencv3.0]

OpenCV (Open Source Computer Vision) is a library for real time computer vision. (This tag is for questions about OpenCV 3.0. Use [opencv] for general questions.)

OpenCV is an open source computer vision library

Version 3.0 released in June 2015. Its documentation can be found here.

For more information, see .

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How i can access elements in OpenCV::Mat?

Actually i am using OpenCV::inRange() to detect a certain color in image.This function returns a OpenCV::Mat.I am having problems accessing individual elements in OpenCV::Mat.
Abdur Rehman
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Redistort the image / undo image rectification

I am using the omnidirectional camera module in OpenCV to find depth maps from input stereo images. I am getting the disparity maps like this: However I want to redistort this particular image so that it looks like the original input image like…
gituser007
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OpenCL can not detect my AMD GPU using OpenCV

I am using AMD Radeon R9 M375. I tried following this answer https://stackoverflow.com/a/34250412/8731839 but it didn't work for me. I followed this:…
Shubham
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BGR to HSV conversion doesn't work with OpenCV Python

I'm trying to detect color-range using OpenCV Python. When I use RGB colors on HSV converted image, it works fine. But when I change lower and upper colors to HSV, it cannot detect colors. Here is a bit dirty code. lower and upper variables are BGR…
she hates me
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Output Video frames are scrolling vertically when reading from rtmp source using python ffmpeg subprocess

This is what I'm trying to do: (1) Read rtmp stream with ffmpeg(python subprocess) and piping to rawvideo (2) processing rawvideo pipe from (1) to opencv readable image using numpy (3) process the image from (2) using opencv for whatever…
nkottapalli
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No matching function for call to 'MatToUIImage'

I am using the OpenCV Contrib framework to preform facial recognition. I need to convert a cv::Mat to a UIImage. However, when I call the MatToUIImage function I get an error. No matching function for call to 'MatToUIImage' This is the code I am…
coder
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How to assigne a cv::Scalar to cv::Mat?

Using the class Scalar implemented in OpenCV, I didn't understand what is the difference between this code: Mat test; test = Scalar::all(0); and this: Mat test = Scalar::all(0); ^ My question is why is the first assignment correct while…
BrainabilGH
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terminating a python loop

I made a program that reads pixels from a camera. I have used a while loop. But I can't close the program from terminal without pressing 'Cltrl + C'. I want to close the program using ESC button ( ASCII 27). I tried the following code, which is not…
zamanmub
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CMake error: 'target is not built by this project' Clion Kotlin

I'm trying to load OpenCV Libraries in CMakeFile.txt but it always ends with this error: CMake Error at CMakeLists.txt:21 (target_link_libraries): Cannot specify link libraries for target "HelloWorld" which is not built by this project. I've…
Andrea Zichittella
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How is the ROC curve plotted in Viola Jones face detection paper?

I am reading paper by Viola and Jones. There they have used ROC curve to measure the accuracy of their classifier. https://www.cs.cmu.edu/~efros/courses/LBMV07/Papers/viola-cvpr-01.pdf Could someone please explain how the ROC curve is plotted in…
Nemi Bhattarai
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Integrating C++ video streaming application with django webframework

We are developing a simple video streaming application that will stream a single channel video over a private WiFi network. The c++ application(using OpenCV) that does the video processing will reside on a Linux server. The users will be able to…
rohkumarj
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Java Implementation of OpenCV::projectPoints seems broken in this basic example

When I run projectPoints function using java code below with the most simple inputs I get what I believe is incorrect answer. Did I miss something? I get this answer (x,y,z)= [{0.0, 1.0, 1.0}, {0.0, 1.0, 5.0}, {0.0, 1.0, 10.0}] (u,v)= [{0.0,…
J.E.Tkaczyk
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Upgrading code that uses OpenCV2.4

I'm trying to upgrade python code that was programed for OpenCV 2.4 to be used with OpenCV 3.3. I found a problem with the flags of the function cv2.calcCovarMatrix, as I show next. The code is this one: # Compute 3x3 covariance matrix covar, mean =…
Pharaun
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ValueError: operands could not be broadcast together with shapes (400,400,3) (400,400)

I am using pyshearlab package to denoise image.The function expects an image shape of equal size.After the code is executed denoising is ok for some images but some images generates an error like this. ValueError: operands could not be broadcast…
Amal Joseph
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IndexError: tuple index out of range -python

Please Help me. I'm running a face recognition detector python program that will display the data from sqllite studio database... import cv2,os import sqlite3 import numpy as np from PIL import Image import pickle recognizer =…
Abin Titus John
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