...
#include <libwebcam/webcam.h>
...
int main()
{
    try{
        webcam::video_settings video_settings;
		video_settings.set_format(webcam::format_JPEG());
		video_settings.set_fps(6);
		video_settings.set_resolution(webcam::resolution(320, 240));
		
		unsigned char device_number = 1;
		webcam::device device(device_number, video_settings);
		device.open();
		for(int i=0; i<100; i++){
		    webcam::image * image = device.read();
		    //do somethig with image
		    delete image;
		}
		device.close();
    }
    catch (const webcam::webcam_exception & exc_){
		std::cout<<exc_.what()<<std::endl;
	}
	return 0;
}