OpenCV Capture from Camera Results in Noisy-like Image

Question

I am using OpenCV on an embedded target board (FriendlyARM mini6410, processor arm 1176 running linux kernel 2.6.38). I compiled OpenCV 2.4.4 library using toolchain provided for the board, found in the ftp (pls see the website of FriendlyARM). I disabled GTK, ffmpeg and enable v4l. The library is compiled successfully.

Then I write code:

#include <opencv.hpp>
#include <highgui/highgui.hpp>
#include <imgproc/imgproc.hpp>
#include <iostream>
#include <stdio.h>

using namespace cv;
using namespace std;

int main()
{
    int i;
    cout << "initialise" << endl;
    IplImage* img=0;
    cout << "capturing ..." << endl;
    CvCapture* capture = cvCaptureFromCAM(2);
    cout << "get here" << endl;
    if(!capture){
        cout << "not capture" << endl;
        return -1;
    }
    cout << "captured" << endl;
    img=cvQueryFrame(capture);

   IplImage* img1 = cvCreateImage(cvGetSize(img),8,3);
   // cvCvtColor(img,img1,CV_RGB2GRAY);
   cvCopy(img, img1);
   cvSaveImage("cam_snap.jpg",img1);
   cvReleaseImage( &img1 );
   cvReleaseImage( &img );
   cvReleaseCapture( &capture );
   cout << "exit" << endl;

   return 0;
}

The code is built successfully. I run the .elf executable in the target board, connected to camera (PS3 eye), but the resulting image looks like a broken television (noise-like):

While in my host, the resulting image is as expected (scene in front of camera). Can you provide me suggestion as to what went wrong or where should I start on debugging?

Answer 1

Okay, confirmed. mini 6410 runs USB 1.0, and ps3 eye needs USB 2.0. I tried the program using standard webcam (chinese product, itech pc camera), works wonderfully. Saved image is showing scene in front of camera

Answer 2

You should check your depth and channels. It is probably a matter of alignement, moreover be careful your image is probably in BGR and not in RGB. And you should use cv::Mat instead of IplImage in C++ and VideoCapture instead of CVCapture.

This sample of code should work. (Not tested on the same arch as your)

#include <opencv.hpp>
#include <highgui/highgui.hpp>
#include <imgproc/imgproc.hpp>
#include <iostream>
#include <stdio.h>

using namespace cv;
using namespace std;

int main()
{
    VideoCapture capture = cv::VideoCapture(0);
    cout << "get here" << endl;
    if(!capture.isOpened())  // check if we succeeded                                                                                                   
         return -1;

    cout << "captured" << endl;
    Mat img;
    capture >> img;
    imwrite("./test.png", img);
    capture.release();
    cout << "exit" << endl;
    return 0;
}

Hope it helped.