Increasing camera capture resolution in OpenCV

Question

In my C/C++ program, I'm using OpenCV to capture images from my webcam. The camera (Logitech QuickCam IM) can capture at resolutions 320x240, 640x480 and 1280x960. But, for some strange reason, OpenCV gives me images of resolution 320x240 only. Calls to change the resolution using cvSetCaptureProperty() with other resolution values just don't work. How do I capture images with the other resolutions possible with my webcam?

Answer 1

I'm using openCV 1.1pre1 under Windows (videoinput library is used by default by this version of openCv under windows).

With these instructions I can set camera resolution. Note that I call the old cvCreateCameraCapture instead of cvCaptureFromCam.

capture = cvCreateCameraCapture(cameraIndex);

cvSetCaptureProperty( capture, CV_CAP_PROP_FRAME_WIDTH, 640 );

cvSetCaptureProperty( capture, CV_CAP_PROP_FRAME_HEIGHT, 480 );


videoFrame = cvQueryFrame(capture);

I've tested it with Logitech, Trust and Philips webcams

Answer 2

Try this:

capture = cvCreateCameraCapture(-1);
//set resolution
cvSetCaptureProperty(capture, CV_CAP_PROP_FRAME_WIDTH, frameWidth);
cvSetCaptureProperty(capture, CV_CAP_PROP_FRAME_HEIGHT, frameHeight);

Answer 3

There doesn't seem to be a solution. The resolution can be increased to 640x480 using this hack shared by lifebelt77. Here are the details reproduced:

Add to highgui.h:

#define CV_CAP_PROP_DIALOG_DISPLAY 8
#define CV_CAP_PROP_DIALOG_FORMAT 9
#define CV_CAP_PROP_DIALOG_SOURCE 10
#define CV_CAP_PROP_DIALOG_COMPRESSION 11
#define CV_CAP_PROP_FRAME_WIDTH_HEIGHT 12

Add the function icvSetPropertyCAM_VFW to cvcap.cpp:

static int icvSetPropertyCAM_VFW( CvCaptureCAM_VFW* capture, int property_id, double value )
{
    int result = -1;
    CAPSTATUS capstat;
    CAPTUREPARMS capparam;
    BITMAPINFO btmp;

    switch( property_id )
    {
        case CV_CAP_PROP_DIALOG_DISPLAY:
            result = capDlgVideoDisplay(capture->capWnd);
            //SendMessage(capture->capWnd,WM_CAP_DLG_VIDEODISPLAY,0,0);
            break;

        case CV_CAP_PROP_DIALOG_FORMAT:
            result = capDlgVideoFormat(capture->capWnd);
            //SendMessage(capture->capWnd,WM_CAP_DLG_VIDEOFORMAT,0,0);
            break;

        case CV_CAP_PROP_DIALOG_SOURCE:
            result = capDlgVideoSource(capture->capWnd);
            //SendMessage(capture->capWnd,WM_CAP_DLG_VIDEOSOURCE,0,0);
            break;

        case CV_CAP_PROP_DIALOG_COMPRESSION:
            result = capDlgVideoCompression(capture->capWnd);
            break;

        case CV_CAP_PROP_FRAME_WIDTH_HEIGHT:
            capGetVideoFormat(capture->capWnd, &btmp, sizeof(BITMAPINFO));
            btmp.bmiHeader.biWidth = floor(value/1000);
            btmp.bmiHeader.biHeight = value-floor(value/1000)*1000;
            btmp.bmiHeader.biSizeImage = btmp.bmiHeader.biHeight *
            btmp.bmiHeader.biWidth * btmp.bmiHeader.biPlanes *
            btmp.bmiHeader.biBitCount / 8;
            capSetVideoFormat(capture->capWnd, &btmp, sizeof(BITMAPINFO));
            break;

        default:
            break;
    }

    return result;
}

and edit captureCAM_VFW_vtable as following:

static CvCaptureVTable captureCAM_VFW_vtable =
{
6,
(CvCaptureCloseFunc)icvCloseCAM_VFW,
(CvCaptureGrabFrameFunc)icvGrabFrameCAM_VFW,
(CvCaptureRetrieveFrameFunc)icvRetrieveFrameCAM_VFW,
(CvCaptureGetPropertyFunc)icvGetPropertyCAM_VFW,
(CvCaptureSetPropertyFunc)icvSetPropertyCAM_VFW, // was NULL
(CvCaptureGetDescriptionFunc)0
};

Now rebuilt highgui.dll.

Answer 4

I am using debian and ubuntu, i had the same problem, i couldn't change the resolution of video input using CV_CAP_PROP_FRAME_WIDTH and CV_CAP_PROP_FRAME_HEIGHT

I turned out that the reason was a missing library. I installed lib4l-dev through synaptic, rebuilt OpenCV and the problem is SOLVED!

Answer 5

Check this ticket out: https://code.ros.org/trac/opencv/ticket/376

"The solution is to use the newer libv4l-based wrapper.

1. install libv4l-dev (this is how it's called in Ubuntu)

2. rerun cmake, you will see "V4L/V4L2: Using libv4l"

3. rerun make. now the resolution can be changed. tested with built-in isight on MBP."

This fixed it for me using Ubuntu and might aswell work for you.

Answer 6

I am posting this to ensure that no one else wastes time on this setproperty function. I spent 2 days on this to see that nothing seems to be working. So I dug out the code (I had installed the library the first time around). This is what actually happens - cvSetCaptureProperty, calls setProperty inside CvCapture class and lo behold setProperty does nothing. It just returns false. Instead I'll pick up using another library to feed OpenCV a capture video/images. I am using OpenCV 2.2