"white clip extension" in VHS HQ, what does it mean

[infoeater]

While reading article on Wikipedia (http://en.wikipedia.org/w/index.php?title=VHS&oldid=569251889) I found a term "white clip extension". Google find only many copies of Wikipedia article. I found that "extension of the white clip level (...) sharpens the picture" on JVC page (http://pro.jvc.com/prof/attributes/tech_desc.jsp?model_id=MDL100671&feature_id=02).

What does "white clip extension" mean? How it enhance sharpness of the picture? Is it enhancing real details too?

[raffriff42]

VHS video is an FM signal (http://en.wikipedia.org/wiki/Frequency_modulation#Magnetic_tape_storage). VHS has a defined sync level of 3.5 MHz and white level of 4.4 MHz. Colors whiter than white (for overshoot purposes) require a higher maximum frequency. I'm guessing as video tape improved, later VHS decks could record higher frequencies, allowing more overshoot. This would make the highlights a little less blown out - which is not actually "sharper." Maximum resolution is not affected, only white clipping.

[marquis]

This might be a stupid question, but could this exist if you were to record with black and white? Even if it were a new black and white VHS opposed to the older tapes?

[raffriff42]

Yeah, some cameras overshoot like a motorboater.