[Devel] Fwd: IKARUS, Peter Karow books ['tension' in splines, Hermite Splines]

[Vadim Plessky]

Will Adams (http://members.aol.com/willadams/index.html) added some comments 
to subj., and after receiving his permission to send those comments to the 
list - here they are.


----------  Forwarded Message  ----------

Subject: Re: IKARUS, Peter Karow books ['tension' in splines, Hermite Splines]
Date: Saturday 14 September 2002 11:16 pm
From: address@hidden
To: address@hidden

(re: Peter Karow saying)
  (like: TrueType has no
 future, as only 70 fonts available in TrueType format, comparing to 1000
 fonts avalable in PostScript format; or that all scanning process should be
 done by hand, via tablet)

That's rather disingenuous since it makes no acknowledgement of when he was
speaking, nor of how accurate his statements have been for the publishing
industry at large (TrueType fonts are converted to Type 1 'cause few
publishers have up-graded their RIPs to accomodate TrueType, and TrueType
handles some things in an un-desireable way (the .notdef character being a
visible square for example).

Similarly, his point on digitization assumes original art (which often is a
much re-worked tissue).

>We are interested *what kind* of splines IKARUS uses (if any), and on any
>other info about IKARUS format.

Karow's book does describe how he intends for digitization to happen, and how
they found it more efficient with the computing power / memory / storage
available to use curve interpolation for their _internal_ Ikarus format.

That's a point which hasn't been emphasized enough in the discussions---IK is
strictly internal and used primarily to store the digitization as a source to
convert algorithmically into other formats. Other formats are derived from
the internal IK format (example code for this is provided in _Digital
Typefaces: Description and Formats_, and each of the formats listed below
gets an appendix to describe its format, and possibly sample code for
conversion). These include:

IK - internal Ikarus format, 15,000 x 15,000 unit emsquare, uses lines and
curve approximation w/ curves defined by _on curve_ points (the better for
hand-digitization).
BE - Bezier Curves---I guess that exporting from IK to BE was Adobe's first
step in making their Type 1 fonts.
CN - Conic Curves
QQ - Quadratic Splines
II - IKARUS with instructions
DI - Display, circles / straights
VC - Vector / circle
BS - Bezier with instructions
VE - vectors
SC - scanlines, run lengths
SN - scanline nibbles
BI - bitmap
GS - grayscale, bytemap

AIUI (this isn't much more than a SWAG) Any discussion of splines with Ikarus
only comes into play when one is converting into the desired sort of spline,
or using splines as an intermediary to another sort of format.

you said in another message:
>My point is that 15 operations per glyph are *reasonable*, and can be
>overviewed/hinted by a man (as you can see from URL above, TT auto-hinter
>results in FL4 are acceptable in mnay cases, but need correction by hand)
>196 operations, not speaking about 600, can't be coded by a man.

I think you mean in a fixed time frame? Joshua Hadley of Projective
Solutions? (the team lead for the hinting of the MS core fonts) would
probably disagree with that last---they put forth man _years_ of effort into
manually hinting said fonts.

To my mind, the ideal thing for typeface design would be to get a working
implementation of a visual and interactive METAFONT design program working
(not one which does outlines as were used for Euler---have you seen the AMS
report on that? Very interesting---but one which actually does / allows
META-design). Follow that up with an implementation of METAFONT in
PostScript, or an automated scheme to derive a Type 1 or TrueType font from a
set of METAFONT inputs, and there'd be no limit to the fonts which one person
could make.

I hope you find this information helpful / useful. The books are quite nice,
and I highly recommend them. (pricey though).

William

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Vadim Plessky
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