aries's profile - activity

I want to estimate noise in a color image. I need to determine if the image is too noisy. Could someone please guide me on how to proceed about this?

I want to determine if a RGB color image is overexposed or underexposed. Could someone please guide me on how to proceed about this?

I am facing segmentation fault while accessing the Mat object. I set the resolution of my webcam to 1024X780 and then I loop around the image from index 0 to less than image.rows and image.columns. I am getting segmentation faults at only index values 778 or 779(Near the boundary). Below is my code. Could someone please explain the reason behind this.

cap.set(CV_CAP_PROP_FRAME_WIDTH,1024);
cap.set(CV_CAP_PROP_FRAME_HEIGHT,780);
cap >> src;
src.copyTo(prevFrame);
for(;;){
    cap >> src;
    src.copyTo(nextFrame);
    pixelCount = 0;
    for( int x = 0; x < nextFrame.rows; x++ )
        for( int y = 0; y < nextFrame.cols; y++ )
            if(prevFrame.at<Vec3f>(x,y)[0] == nextFrame.at<Vec3f>(x,y)[0] &&
               prevFrame.at<Vec3f>(x,y)[1] == nextFrame.at<Vec3f>(x,y)[1] &&
               prevFrame.at<Vec3f>(x,y)[2] == nextFrame.at<Vec3f>(x,y)[2]){
                    pixelCount++;
                    if (pixelCount > threshold){
                        cout << pixelCount;
                    return false;
            }
    }

I am trying to open a raw color image that I have captured from the camera using opencv. But imread does not seem to be able to open it. Below is my code:

Mat original = Mat(1792,1344, CV_8UC3);
original = imread("image.raw", 1);
if(original.empty()){
cout<<"unable to read image";
waitkey(10);
exit(0);    
}

Can someone please help me find the solution?

PS: I am using my own debayering technique to get the raw image from the sensor and writing it to the disk.

@FooBar : Can you please guide how to compile with Qt-support? I have never used Qt before.

How can I display text on a video in opencv? I know that putText() allows us to display text on image. I need to change the text depending on certain scenarios on the same video. My current code is as below. It displays text on only one frame and disappears as putText() inserts text in just one image. Someone please help me on this.

int indicator = -2;
VideoCapture cap(0); // open the default camera
if(!cap.isOpened())  // check if we succeeded
return -1;
namedWindow("Display Window",1);
for(;;)
{
    cap >> src;
    if(indicator == -2)
    {
        putText(src, "Press 'c' to capture an image", cvPoint(100,50), FONT_HERSHEY_COMPLEX_SMALL, 0.8, cvScalar(0,0,0), 1);
        putText(src, "move in", cvPoint(50,200), FONT_HERSHEY_COMPLEX_SMALL, 0.8, cvScalar(0,0,0), 1);
    }
    imshow("Display Window", src);
    if (waitKey(33) == 'c' )
    {
        indicator = calculateValue();
        if(indicator == -1)
            putText(src, "move in", cvPoint(50,200), FONT_HERSHEY_COMPLEX_SMALL, 0.8, cvScalar(0,0,0), 1);
        else if (indicator == 1)
            putText(src, "move out", cvPoint(50,200), FONT_HERSHEY_COMPLEX_SMALL, 0.8, cvScalar(0,0,0), 1);
        else if (indicator == 0)
            putText(src, "End", cvPoint(50,200), FONT_HERSHEY_COMPLEX_SMALL, 0.8, cvScalar(0,0,0), 1);
     }
    imshow("Display Window", src);
}

@matman Thanks for the reply. I found on the internet that laplacian method is quite good technique to compute the sharpness. I was trying to implement it. How do we get the sharpness measure after applying the Laplacian function? Below is the code:

    Mat src_gray, dst;
    int kernel_size = 3;
    int scale = 1;
    int delta = 0;
    int ddepth = CV_16S;

    GaussianBlur( src, src, Size(3,3), 0, 0, BORDER_DEFAULT );

    /// Convert the image to grayscale
    cvtColor( src, src_gray, CV_RGB2GRAY );

    /// Apply Laplace function
    Mat abs_dst;

    Laplacian( src_gray, dst, ddepth, kernel_size, scale, delta, BORDER_DEFAULT );

    //compute sharpness
   ??

I am working on a project wherein I have a camera and I need to find the distance between the lens and the object to produce the sharpest image. The camera has the provision to adjust the position of the lens. I have to determine the distance from the lens and the object which can produce the sharpest image. Can anyone please provide me an idea on how this can be achieved?

@theodore: The function is in Opencv 3.0. Is there something similar in opencv 2.4.10?

I am working on a project and I need to perform white balancing on the images. I am using opencv 2.4.10. Is there any built-in functionality in opencv to do white balancing? I searched on the internet but could not find any. If not, can anyone please guide me how this can be achieved?

I am trying a simple program to read an image and display it. However, imread is not reading the image. I checked on the internet but many told that its because of mixing debug library and release library. How do I know which library i am using? Is it someother issue? please help.

src = imread("colorchart.bmp", CV_LOAD_IMAGE_COLOR); if(! src.data ) // Check for invalid input { cout << "Could not open or find the image" << std::endl ; return -1; } imshow( source_window, src );

Sorry I just edited it.

I am new to opencv, I working on detecting the corners of colored squares from an image. I came across this function which seems to work for my problem "ocl::cornerHarris". Could someone please provide me a example of how to use this function?