Quote:
Originally Posted by Penthode
An important factor which is being overlooked is the Kell Factor.
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The Kell factor is largely an empirical fudge. Nothing wrong with that because it reflects how we actually perceive H and V resolution. I don't have the evidence to prove it but I strongly suspect that the work that Kell did applies only to displays with an approximately gaussian spot shape. This is more or less true for CRTs and totally wrong for LCDs. Not sure what happens to Kell if you use spot wobble on a CRT.
It was widely observed in the UK that 625 pictures seemed less sharp than 405. This may have been due to relatively poor HF response in some sets of the time. It may also be a psycho-optical effect of a visible line structure being perceived as sharper.