Path: utzoo!mnetor!uunet!husc6!cmcl2!nrl-cmf!mailrus!umix!rutgers!aramis.rutgers.edu!lou From: lou@aramis.rutgers.edu (Lou Steinberg) Newsgroups: comp.graphics Subject: Re: Grey Scale Index Message-ID: Date: 24 Mar 88 14:01:08 GMT References: <1988Mar22.213059.17809@lsuc.uucp> Organization: Rutgers Univ., New Brunswick, N.J. Lines: 28 To: jimomura@lsuc.UUCP In article <1988Mar22.213059.17809@lsuc.uucp> jimomura@lsuc.uucp (Jim Omura) writes: > The following is a couple of letters from Lou Steinberg > to me and a couple of postings of mine to BIX. > [regarding the a discussion we've been having about calculating an > index, based on pixels and brightness levels/pixel, for how good a > display is at showing pictures] I'm not sure, but I think you may be missing my main point: no SINGLE number can do the job. Given two displays, say 256 x 4 bits vs 512 x 2 bits, one may be better for a picture with large areas of smoothly changing brightness and subtle contrasts while the other may be better for pictures with lots of fine detail. No single number can capture something like this. Compare this, for instance, with the way we describe speakers for good stereo systems: we show a graph that shows how the speaker responds over a range of sound frequencies, since one speaker may be better at high frequencies and another at low ones. Similarly, I was suggesting a graph of how well a display handles different spatial frequencies, i.e. different sizes of detail. Whether you use a single measure based on pixels across the whole screen or across 1/100 of the screen, or whatever, that one number must be misleading for certain classes of pictures and certain pairs of displays. -- Lou Steinberg uucp: {pretty much any major site}!rutgers!aramis.rutgers.edu!lou arpa: lou@aramis.rutgers.edu