image appears green after capture OpenCV - c++

I have this code which captures image from Webcam using OpenCV:
#include <opencv2/objdetect/objdetect.hpp>
#include <opencv2/highgui/highgui.hpp>
#include <opencv2/imgproc/imgproc.hpp>
#include <iostream>
#include <stdio.h>
using namespace std;
using namespace cv;
int main( )
{
VideoCapture cap(0); // open the default camera
if(!cap.isOpened()) // check if we succeeded
return -1;
Mat meter_image;
cap >> meter_image;
imwrite("/boneCV-master/img.jpg", meter_image);
return 0;
}
I get following image as output.
Previously it was working fine. I don't know what is happening. I tried simplest of all codes upon googling but nothing worked. Please let me know what could be wrong with it.
thanks in advance.
EDIT
One thing I forgot to mention is that i am working on beagleBone Black. this same piece of codes works great with my mac.

Maybe adding frame checking will be helpful.
Mat meter_image;
while(meter_image.empty()){
cap >> meter_image;
}
But there's a risk of infinite loop.

Related

Opencv 3.2 read mpeg files too slow

I am going through the book Learning OpenCV 3 and test out the video example 2.3. I could edit, compile and run it, but the problem is that it closed down immediately.
// DisplayPicture.cpp : Defines the entry point for the console application.
//
//#include "opencv2/opencv.hpp" // Include file for every supported OpenCV function
#include "opencv2\imgproc\imgproc.hpp"
#include "opencv2\highgui\highgui.hpp"
#include <opencv2/videoio.hpp>
#include <stdio.h>
#include <string.h>
using namespace cv;
using namespace std;
int main(int argc, char** argv) {
namedWindow("video3", WINDOW_AUTOSIZE);
VideoCapture cap;
cap.open( string(argv[1]));
int tell = 0;
Mat frame;
for (;;) {
cap >> frame;
//waitKey(30);
if (frame.empty())
{
break;
//end of film
}
imshow("video3", frame);
}
return 0;
}
I found that my computer processed the data too fast. It could not read the next frame fast enough. if (frame.empty()) became true the program reached the break statement and ended.
By adding a waitkey of 30 millisec before viewing the image frame, the video program works very well. At least I can view the video. Since this example is from the 'bible' it should work, but not with my computer.
I am running a MSI gt72 2PE computer with nvidia gtx880m. Not sure if that matters.
I assume that adding a waitKey(30) is not appropriate, so I am seeking suggestions as to what could be done differently.

I get different results for same image in a program

I made a small program that calculates the number of white pixels in a grayscale image. I get different results if I open the image twice in the same program. Same if I display the intensity of the pixels, it changes even if it is the same image. If anyone sees where the problem is please help.
#include "opencv2/imgcodecs.hpp"
#include "opencv2/highgui.hpp"
#include "opencv2/imgproc.hpp"
#include <iostream>
using namespace std;
using namespace cv;
int main()
{ int i=0,j,nbr=0,nbr1=0;
Mat image=imread("2_.png",CV_LOAD_IMAGE_GRAYSCALE);
Mat image2=imread("2_.png",CV_LOAD_IMAGE_GRAYSCALE);
for(i=0;i<image.rows;i++)
{
for( j=0;j<image.cols;j++)
{if (image.at<int>(i,j)!=0)
nbr++;
if (image2.at<int>(i,j)!=0)
nbr1++;
}
}
printf("%d\n %d\n",nbr,nbr1);
return 0;}
Thank you for your help.
It is may be because you need to avoid using int, but uchar for grayscale image. Using int you go out of image memory.

opencv build failed with xcode

I have a problem with a webcam capturing in opencv.
This can be built successfully:
#include <iostream>
#include "opencv2/highgui/highgui.hpp"
#include "opencv2/imgproc/imgproc.hpp"
#include "opencv2/core/core.hpp"
using namespace cv;
int main() {
// VideoCapture cap(0);
// while(true){
// Mat Webcam;
// cap.read(Webcam);
// imshow("Webcam", Webcam);
// }
}
However, this is not:
#include <iostream>
#include "opencv2/highgui/highgui.hpp"
#include "opencv2/imgproc/imgproc.hpp"
#include "opencv2/core/core.hpp"
using namespace cv;
int main() {
VideoCapture cap(0);
while(true){
Mat Webcam;
cap.read(Webcam);
imshow("Webcam", Webcam);
}
}
There is no error or warning message popped out, so I can't solve it by myself.
Any idea is appreciated!
Updates:
Error message
It seems something went wrong when I updated xcode.....
Error message 2
Your code is perfectly ok except following line after imshow:
waitKey(10);
It will provide ui thread to draw the frames. Without this delay ui thread can not be updated or get time slice from cpu.

RTSP: error while decoding MB

I have problem with RTSP stream from my BOSH cammera. While Im getting stream to my program with this code:
VideoCapture cap("rtsp://name:password#IPaddress:554");
i get some stream, but after few images i get this error:
enter image description here
and then, my stream looks like this:
enter image description here
I saw that there are more solutions for my problem, like using VLC libraries to resolve my problem, or GStreamer. But this is no solution for my problem, because I need to use OPenCV libraries, save every image to MATRIX, and Im then using my special image processing..
Does anybody have solution ?
Is it possible to create some buffer ? If answer yes, can anybody write HOW ?
Here is my code:
#include <opencv\cv.h>
#include <opencv2\highgui\highgui.hpp>
#include <opencv2\imgproc\imgproc.hpp>
#include <iostream>
#include <stdio.h>
using namespace std;
using namespace cv;
int main()
{
Mat frame;
namedWindow("video", 1);
VideoCapture cap("rtsp://name:password#IPaddress:554");
if(!cap.isOpened())
{
cout<<"Camera not found"<<endl;
return -1;
}
while(1)
{
cap >> frame;
if(frame.empty()) break;
resize(frame, frame, Size(1200, 800), 0, 0, INTER_CUBIC);
imshow("video", frame);
if(waitKey(1000) >= 0) break;
}
return 0;
}

Webcam Streaming is mirrored using OpenCV 3.0 + Visual Studio 2013

Every time i compile this code the webcam streaming is mirrored like I lift up my right hand and it appears like if it was my left hand on the screen instead and after a couple of re-compiling an error message appeared and the code never worked again.
The error:
Unhandled exception at 0x00007FFB3C6DA1C8 in Camera.exe: Microsoft C++ exception: cv::Exception at memory location 0x000000D18AD5F610.
And no other option left except to break the process.
The code:
#include <opencv2/highgui/highgui.hpp>
#include <opencv\cv.h>
using namespace cv;
int main(){
Mat image;
VideoCapture cap;
cap.open(1);
namedWindow("Window", 1);
while (1){
cap >> image;
imshow("window", image);
waitKey(33);
}
}
I don't know if something wrong with my code I've just started learning opencv !
#include <opencv2/highgui/highgui.hpp>
#include <opencv\cv.h>
using namespace cv;
int main(){
Mat image;
VideoCapture cap;
cap.open(1);
namedWindow("Window", 1);
while (1){
cap >> image;
flip(image,image,1)
imshow("window", image);
waitKey(33);
}
}
just Flip the image horizontally that will do Find More Here
There is nothing wrong when your image is mirrored on the vertical (/x) axis (I guess in your example you are using a built-in (laptop) webcam).
A (very) simple code for capturing and showing your image could be the following:
// imgcap in opencv3
#include "opencv2/highgui.hpp"
#include "opencv2/videoio.hpp"
int main() {
cv::VideoCapture cap(0); // camera 0
cv::Mat img;
while(true) {
cap >> img;
cv::flip(img,img,1);
cv::imshow("live view", img);
cv::waitKey(1);
}
return 0;
}
When using OpenCV 3 you should include headers like:
#include <opencv2/highgui.hpp>