Older blog entries for haruspex (starting at number 115)

bolsh wrote,

in some locales the alphabet is ordered "AaBbCc....Zz", and in others it uses the ASCII ordering of "ABC...Z...abc...z". This depends on the LC_COLLATE environment variable

Aha! I never would have thought of a non-ASCII collating sequence. So herzi's original problem might have been caused by a collation aAbB..zZ?

herzi: Curious sed problem. I am not a sed guru - although I always wanted to "get my head around it" - but I learned the following.

GNU sed is case sensitive by default. The man page for BSD sed is coy on case sensitivity and doesn't mention any switches for it. It appears to be case sensitive.

OS X has BSD sed of unknown version, so no GNU extensions like '+' in regexps

You need to use sed -r to get the extended regexps (see info sed section on extended regexps)

Neither version showed the [list] problem you described:

(Gentoo)
toby@jumpy toby $ echo FOO|sed -n -e 's/[A-Z]/X/p'
XOO
toby@jumpy toby $ echo foo|sed -n -e 's/[A-Z]/X/p'
toby@jumpy toby $ 

 (OS X)
imac:~ toby$ echo FOO|sed -n -e 's/[A-Z]/X/p'
XOO
imac:~ toby$ echo foo|sed -n -e 's/[A-Z]/X/p'
imac:~ toby$

I was using GNU sed version 4.0.7 (sed -V) on a Gentoo box, and OS X 10.3.5.

Other sed tricks I amused myself with:

toby@jumpy toby $ date|sed -r -e 's/[0-9]/X/g'
Sat Sep XX XX:XX:XX EST XXXX
imac:~ toby$ date|sed -e 's/[^ ]/X/g'
XXX XXX XX XXXXXXXX XXX XXXX
imac:~ toby$ date|sed -e 's/[^0-9]/ /g'
        26 14 48 39     2004

(update) DV:

Sure I come from an ISP provided address range (free.fr) but the domain is legit, I even have a working reverse DNS.

That's a common administrative measure. You may also find (as I recently did with sympatico.ca) that the ISP blocks SMTP from subscribers except to its own SMTP server. The solution, in both cases, is to deliver mail via the ISP's SMTP server. It's simple configuring a gateway's sendmail or postfix to do so.

raph, thanks for the informative post. I think I'll have to read it twice and follow the links.

the perturbation of the middle knot damps out very quickly as you traverse (S-shaped) Cornu spiral segments, but doesn't damp out at all with the circular arcs

IKARUS' circle fitting method is actually well damped, and behaves much more like the second example (as does METAFONT's IIRC).

I'm willing to tolerate a significantly larger number of primitives in this internal representation than either input through the UI or exported into a font file format after all manipulations have been done

Doesn't this have some major implications for hinting? I get the impression from FontFocus that stroke-oriented hinting is still a favoured approach.

I keep mentioning IKARUS because for many years it was the gold standard for these purposes... it's interesting you mention auto-tracing. URW produced a rather nice companion program which traced bitmaps into IK format, called LINUS. I still have a copy of the Mac version.

elanthis: Point taken. The battle for freedom doesn't put me in a joking mood. I'll celebrate when the likes of $CO and M$ are properly buried with a silver stake perforating their carcasses in the necessary manner.

(Yeah, I know, the stake doesn't have to be silver. But you can't be too careful. And it's 1.17am.)

yeupou: I agree. Could GPL-hate be self-hate?

Cubic Beziers are actually pretty good at making an S curve, in my opinion. Certainly, it's not uncommon in professional fonts to see a single Bezier traverse from a vertical tangent in the upper left corner to another vertical tangent in the lower right.

I agree Beziers are efficient, but I don't think this should seduce us into concluding they are natural.

If you draw the main slope of the S with, say, eight arcs, then the centers should describe a fairly continuous path in and of themselves. ... But if you don't do a good job visualizing the radii of curvature, and put the tool in novice hands, my guess is that you'll see bad curves.

That's a good point. But rather than having the user think about the circles, I wonder if they could use the abstraction of a digital spline and ducks (the non-mathematical meaning of spline). I suspect this is what Dr Karow had in mind when he came up with IKARUS' curve model.

it's probably not anywhere nearly as painful as you might think to work directly in the space of the Cornu parameters

That sounds interesting.

having an uneven baseline or x-height line is a pretty serious artifact

Surely only subpixel placement can help with non-integral lineskips? But it seems to me that (at a cost of performance, i.e. glyph caching), FontFocus could be adapted to subpixel positioning? (In the vertical, to solve the baseline problem.)

The CoolType samples in your paper do not work. In my opinion the subpixel rendering on OS X and XP (and Adobe Reader 6) does a fine job; the screen dump can only work in exceedingly rare circumstances (1:1, digital LCD of correct triplet ordering, etc) and should be deleted from the paper as a misleading comparison.

yeupou:

she said windows, not Microsoft Windows. Well, as I understand it, the company does not own the word windows, but the trade mark Microsoft Windows.

You missed Michael's point. Regardless of what M$ "owns", in common usage, the word "windows" has gained another (less useful) meaning. In real life this overloading easily results in the kind of ambiguity that his anecdote illustrated.

AlanHorkan, you might enjoy this great tune from Monty Python's irrepressible Eric Idle.

tk:

<small>people who succumb to the threat of the Ivan hurricane and run away are sending the wrong signal to Ivan. We must stand strong in the face of Ivan. We must not allow Ivan to disrupt our way of life and attack our cherished institutions. </small>

Hilarious, thanks :)

PS. Advogato, why can't me have <small>? (Thanks for allowing <cite>)

raph, circle segments are indeed the primitive used by IKARUS, as I've mentioned here before. This is clear from the exposition in Dr Karow's book (op cit.) and the source code therein. Also, I relate them to METAFONT deliberately, as this was explicitly the ideal around which Hobby's Bezier generation was designed. Again, this is derived from the technical descriptions given in The METAFONTbook. Of course, I know METAFONT's underlying representation and rendering engine works with Beziers, but concerning the higher level user abstraction, I stand by what I have asserted. I understand where Hobby departs from pure circles. In fact METAFONT's overall approach seems to solve most of the difficulty.

circular arcs do not have this property. You need quite a few of them to closely fit an ellipse, say.

Yes, I agree with what you write here, but I am not sure it matters. The fact is, any geometrical figure - ellipse, circle, parabola - is irrelevant to the problem of fitting a natural, drawn curve. Pure geometric shapes (with the exception of straight lines) rarely occur in a letter outline, so I disregard them as modelling test cases. Instead, I ask, how well can this primitive deal with a pre-mathematical, natural curve, as might have come from the designer's hand? How awkward is the translation? (Your curve continuity arguments are relevant theoretical ammunition here I think, although my assessments are usually subjective, not objective.)

My counter-assertion would be, for a natural curve, Beziers are not necessarily better than circle segments and further that counting control points does not prove this either way. My gut tells me that Beziers are excellent for rendering purposes but horrible for curve modelling. I certainly see advantages for Cornu over both these representations, and you've given some interesting reasons.

I have studied many IKARUS markups and not found them excessively overspecified. (It would be nice to hear from an IKARUS veteran on this.) One very intriguing thing about IKARUS is that most markups I've seen were made by non-technical draughtsmen, usually type designers themselves - Zapf, Frutiger, Spiekermann. Whereas no-one can do good Bezier drawings without a lot of training - and such drudgery would waste the time of a designer of this calibre. It took me a few years to learn how to "trick" Beziers into looking natural - and it's always a compromise.

In sum, my subjective assessments generally lead me to feel that IKARUS splines - or let's say, a mechanical spline and ducks - are quite natural to the draftsman and designer; and Beziers could not be more artificial and difficult.

We are coming at this from different angles, however. You're the mathematician, and I am just a typographer who isn't happy with the compromises that plague digital type.