Xref: utzoo sci.electronics:10801 comp.std.internat:652 rec.video:11275 comp.graphics:10561 Path: utzoo!attcan!uunet!zephyr.ens.tek.com!gvgpsa!gold!johna From: johna@gold.GVG.TEK.COM (John Abt) Newsgroups: sci.electronics,comp.std.internat,rec.video,comp.graphics Subject: Re: I don't need HDTV! Message-ID: <867@gold.GVG.TEK.COM> Date: 22 Mar 90 15:19:37 GMT References: <5478@okstate.UUCP> Organization: Grass Valley Group, Grass Valley, CA Lines: 35 In article <5478@okstate.UUCP> minich@a.cs.okstate.edu (MINICH ROBERT JOHN) writes: >From article , by bas+@andrew.cmu.edu (Bruce Sherwood): >> The analogy with audio is that a CD with frequency response out to 10 >> MHz would not sound better than one with frequency response out to 20 >> KHz, because the human ear can't hear the higher frequencies. > > Well, it probably would sound a bit better. Consider this: >A 20KHz sample on CD looks something like this > * * * * * * * * * * >* * * * * * * * * * >which is just a dumb square wave. Sure, it's at high enough of a pitch >that most people wouldn't be able to discriminate between it and a pure sine >of the same requency, but what happens if, say, you have a 20,001Hz waveform? >Then, 20KHz just isn't enough to provide a nice, "symetric" waveform. Thus, >you get a somewhat harsh sound. But the 20 KHz square wave is just a "dumb" sine wave after it goes through the re-construction filter. And, as any student of Fourier will tell you, the only thing that can change the periodic shape of a sine wave are harmonics - the first of which for a 20 KHz waveform occurs at 40 KHz. Nobody can hear 40 KHz. >...... Here's >an analogy (and an excuse to post here): The human eye can only discern between >a limited amount of colors, especially in small areas. The number is quite >small (on the order of 100s). So, should we abandon 24bit color displays since >we _shouldn't_ be able to tell the difference? Bad analogy because it's not always applicable, e.g., the eye is extremely sensitive to correlated discontinuities in an image. The number of different colors that are discernable when seperated by distinct line is far greater. Matter of fact, 10 bit RGB makes better pictures. - John Abt, Grass Valley Group