It is important to clearly comprehend that quality of analog picture corresponds to maximum 768x576 in PAL/SECAM and 640x480 in NTSC systems. TV picture is captured exactly with this resolution. Capturing the picture with higher vertical resolution is impossible due to the number of lines in frame (576 – PAL/SECAM, 480 – NTSC). Higher horizontal resolution is unpractical because it will not impruve the picture quality.
On the display the picture can be of any size. It is scaled by display adapter to arbitrary size, up to full screen.