I am using the video capture sample.  It writes out what the webcam sees to the little window the app is running in.  What i really want is in a separate function to save what the webcam sees like for instance when a key is pressed, but not have the webcam preview up unless a special key is held down.

I.e.
the web cam is on.
No preview is shown, instead other stats are up on the display.
When say key 1 is pressed, the webcam image is snapped and saved.  No image perview.
When key 2 is pressed, instead of stats being drawn on display.  Webcam image is being rendered.  I am not sure how to do this, the primary display is what is getting me...and I guess it has a constant variable known as g ?

I say it has a constant named g by this:
Code:

void draw()
{
image(myCapture, 0 ,0); //draws my webcam to the main window dont want this all the time
}
void sendImage()
{


  ImageToTwitter img = new ImageToTwitter(this);
  img.post(apiurl,"jpg-test","", "", msg, true, img.getBytes(g)); 
}
//what is the img.getBytes(g) doing?  its getting the image g from //somewhere, what type of image is that?
 

Still new to the way processing works and draws, looking for help here.

Thanks,
Shane