Re: Convert old formats to OpenType?

This "thread" refuses to die ... and AFAICS "VidTheKid" is correct in his
posting. Meanwhile let's take a look at the TrueType Reference Manual that
is on-line at Apple's web site.

http://developer.apple.com/fonts/TTRefMan/index.html

Please pay particular attention to Appendix E, the section titled

"Converting Outlines to the TrueType Format"

http://developer.apple.com/fonts/TTRefMan/RM08/appendixE.html


Where the developers of the TrueType font format essentially weasel their
way around the fact that you *cannot* convert a cubic Biezer to the
quadratic format used by TrueType by saying

"...
>From cubics to quadratics

It is possible that the outlines you obtain will be described as cubic
curves. If so, it is not possible to perform an exact conversion between
the two formats. It is, however, possible to convert the curve descriptions
to the degree of accuracy required.
...."

What they neglect to mention is that it will require *at* *least* twice as
many "nodes" to describe a **similar** curve using the quadratic format.

It seems that the scientists at Xerox PARC ... and later Adobe ... made the
correct decision to use the cubic (Biezer) curve format to describe type
outlines when they designed the PostScript page description language ...
and the PostScript "Type 1" font format ... way back in the 1970's!





"VidTheKid" <vidthekid@xxxxxxxxx> wrote in message
news:1119633993.441013.314640@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
> Michael Strickland said:
> > I guess I assume the TT type is "better" because it
> > has details and curves not achievable by the limited number of nodes in
> > the Type 1 version.
>
> Actually, the Type 1 version isn't "limited" at all. It sounds like
> you assume it has fewer nodes because there is a numerical limit or
> something. Actually, think of it this way: The TT version *requires*
> more nodes to approximate the same outline as in T1 because TT's
> quadratic curves are more limited in what they can do.
>
> The most notable difference between quadratic and cubic curves is that
> cubic curves can gracefully transition from curving one way to the
> other. In order to simulate the same curve with quadratics, you would
> have to use two curves. And even then, the transition between the two
> isn't very graceful. Adding a third, straight segment between the two
> quadratics would help there, but it still only approximates the grace
> of the cubic.
>
> I hope, from this description, you can see how two or three quadratic
> segments are sometimes required to approximate the path of a single
> cubic segment, and are therefore an inferior form.
>


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