Xref: utzoo comp.fonts:409 comp.lang.postscript:1146 Path: utzoo!dciem!trigraph!john From: john@trigraph.UUCP (John Chew) Newsgroups: comp.fonts,comp.lang.postscript Subject: Re: METAFONT & PostScript Message-ID: <425@trigraph.UUCP> Date: 11 Nov 88 20:27:43 GMT Article-I.D.: trigraph.425 References: <902@cps3xx.UUCP> <10417@s.ms.uky.edu> <422@trigraph.UUCP> <3455@pt.cs.cmu.edu> <423@trigraph.UUCP> <10936@reed.UUCP> Reply-To: poslfit@gpu.utcs.utoronto.ca Organization: Trigraph Inc., Toronto, Canada Lines: 91 In article <10936@reed.UUCP> barry@reed.UUCP (Barry Smith) writes: >In article <423@trigraph.UUCP> you write: --- (I volunteer myself as the unattributed author of the following :-) >>I envisage a good PostScript font (one that has gone to the expensive >>end of the time-quality tradeoff) working as follows. At reasonable >>font sizes, the font is represented as an outline with non-linear >>scaling of various dimensions. At extremely small font sizes (w.r.t. >>device resolution), the font becomes a pre-computed bitmap to ensure >>that not one pixel is painted that shouldn't be. >> >>I will readily admit that I have not designed such a font, nor would >>I look forward to doing so, except by writing a METAFONT-PostScript >>translator, but it is well within PostScript's abilities to execute >>such a font. >> >>I also believe that the quality possible with such a font would be >>very difficult to imitate in METAFONT, though this may just be a >>PostScript programmer's bias. Can one easily make `this pixel stays >>on, but that one should be turned off' decisions in METAFONT? > > >John, pardon me for being so short, but you really don't know what you're >talking about here. Why don't you take a look at the Metafont book? >Keep in mind the experience and credentials of the author, too. Hmm. Pardon me for taking offense at your shortness, but although I don't have a copy of the METAFONT book in front of me, I have read it from cover to cover. I am also aware of Knuth's credentials, as a mathematician, a computer scientist and as a type designer, but prefer to discuss matters such as a comparison of features of METAFONT and PostScript in terms of the documented capabilities of each without resort to argument by reference to authority or to ad hominem attacks. >In more practical terms, one might pose the question thusly: "At 300 dpi, >does PostScript rasterize outlines (of, say, Times Roman) as well as >Metafont rasterizes, say, Computer Modern 10 point?" And the answer, >quite simply, is that it's no contest. ... or at least not a fair contest. It has been pointed out that both PostScript and METAFONT are capable of pixel-level adjustments to individual fonts, though I have yet to hear arguments opposing my suggestion that this is easier in a language such as PostScript which inherently supports both bitmap and algorithmic fonts, rather than in METAFONT where the adjustments if any are best made to individual rasterizations using a bitmap editor. Thus in principle, there is no reason why both languages cannot generate identical bitmaps for a given font. For example, you could take rasterizations of CMR at a large number of point sizes and write a PostScript font that would merely interpolate between them. This would not be elegant, but the final product would be pixel-wise identical. So to take a PostScript font and a METAFONT font, representing two completely different faces and judge the languages solely on that basis is ridiculous. The most one can infer from such a comparison is a subjective opinion concerning the relative skills of the type designers who designed each font, and the degree to which each were familiar with the languages with which they dealt. >It's actually quite an interesting comparison, and an education to the >untrained eye; what previously appeared to be clear, crisp Times Roman >characters suddenly become muddy and coarse. I'm sure if the person who ported Times Roman to PostScript had had fewer constraints on his/her time and the font's own parameters, Times Roman would have more low-resolution special-casing code. >(Here I'm speaking solely of rendering, not esthetics; personally, I >can think of several fonts I might prefer to Computer Modern for my uses.) Are you ... "keep[ing] in mind the experience and credentials of the author" when you say that :-)? Not that I disagree... it's hard for me to decide which strikes me as more of an esthetic crime: Computer Modern at any size or Times Roman at 10 pt on a 300 dpi device. >Another respondent referred to the poor quality of 78 dpi fonts rendered >by Metafont. I agree wholeheartedly (as, I believe, does Knuth); it may be >perfectly correct to say that automatic rendering of low-resolution fonts >from outlines is beyond the state of the art. To re-iterate: one thing that is nice about PostScript is that after you have hand-tuned low-resolution rasterizations, you can incorporate them easily enough into a font and not rely on automatic processes. John Chew -- john j. chew, iii phone: +1 416 363 8841 AppleLink: CDA0329 trigraph, inc., toronto, canada {uunet!utai!utcsri,utgpu,utzoo}!trigraph!john dept. of math., u. of toronto poslfit@{utorgpu.bitnet,gpu.utcs.utoronto.ca}