[mpeg-OTspec] Toward a Composite Font format specification

[Ken Lunde]

Mikhail,

While I cannot answer for daan, as a native speaker of English, the  
word "magnification" conveys to me a rather strong sense of  
uniformity, so I don't think that separate X- and Y-axis scaling  
parameters are necessary. On the other hand, the word "scaling" does  
not convey a sense of uniformity, so it can go either way (separate X-  
and Y-axis scaling parameters or a uniform scaling parameter).

Regards...

-- Ken

On 2009/08/25, at 13:12, Mikhail Leonov wrote:

> Daan,
> I agree, these properties need to have distinct names that emphasize  
> the difference in how metrics are scaled, as opposed to how scale  
> factors are specified.
>
> In addition, should glyph magnification property have separate X and  
> Y scale factors as well? I don’t have concrete scenarios in  
> mind that would use this feature yet, but it makes sense in terms of  
> symmetry.
>
> Best regards,
> Mikhail Leonov
> Microsoft
>
> From: mpeg-OTspec at yahoogroups.com [mailto:mpeg- 
> OTspec at yahoogroups.com] On Behalf Of Daniel Strebe
> Sent: Friday, August 21, 2009 5:04 PM
> To: Ken Lunde; mpeg-OTspec at yahoogroups.com
> Subject: Re: [mpeg-OTspec] Toward a Composite Font format  
> specification
>
>
>
> Colleagues,
>
> As I explained in my earlier message found at the bottom of this e- 
> mail, the two kinds of scaling are independent and mutually  
> compatible operations. Both are necessary simultaneously for a good  
> recipe in some situations.
>
> ScaleFactorX/ScaleFactorY use the baseline as an anchor and scale  
> everything concerning the glyph, including the outline, kerning,  
> escapements, and advance.
>
> Uniform scaling, on the other hand, scales from the center of the  
> ideographic box, and does not affect anything but the glyph  
> impression. Most importantly, it does not affect horizontal or  
> vertical advance.
>
> Both kinds of scaling are needed simultaneously when adjusting  
> component fonts of an ideographic script when the component fonts  
> contain ideographic boxes of differing aspect ratios and  
> differing “color”. Color refers to the foreground/ 
> background ratio of a glyph as determined by of amount of the  
> advance width that the average glyph consumes, and the design weight  
> of the typeface.
>
> They should be given distinct names to distinguish the semantics.  
> Perhaps:
>
> Glyph magnification, in place of “uniform scaling”
> Character scaling, to refer to ScaleFactorX/ScaleFactorY
>
> Regards,
>
> ― daan Strebe
> Senior Computer Scientist
> Adobe Systems Incorporated
>
>
> On 09/08/21 13:59, "Ken Lunde" <lunde at adobe.com> wrote:
>
>
> Mikhail,
>
> While I cannot answer for daan, I have observed that InDesign's
> Composite Font dialog allows all three to be applied independent of
> one another. My gut feeling is that their use should be mutually
> exclusive, meaning ScaleFactor to be applied to both axes, or
> ScaleFactorX+ScaleFactorY as a pair to be set independent of one
> another. Perhaps daan can describe a usage scenario in which both
> forms of scaling are required.
>
> I would think that any use of both forms of scaling could also be
> adequately described in terms of only ScaleFactorX+ScaleFactorY as a
> pair.
>
> Regards...
>
> -- Ken
>
> On 2009/08/21, at 13:53, Mikhail Leonov wrote:
>
> > Ken and Daan,
> > Do you think ScaleFactorX+ScaleFactorY pair and ScaleFactor should
> > be mutually exclusive, or are there examples where using both forms
> > of scaling in the same entry provides value to the recipe creator?
> >
> > Mikhail Leonov
> > Microsoft
> >
> > -----Original Message-----
> > From: mpeg-OTspec at yahoogroups.com <mailto:mpeg-OTspec%40yahoogroups.com 
> >  [mailto:mpeg-
> > OTspec at yahoogroups.com <mailto:OTspec%40yahoogroups.com> ] On  
> Behalf Of Ken Lunde
> > Sent: Friday, August 14, 2009 6:07 PM
> > To: mpeg-OTspec at yahoogroups.com <mailto:mpeg-OTspec%40yahoogroups.com 
> >
> > Subject: Re: [mpeg-OTspec] Toward a Composite Font format
> > specification
> >
> > daan,
> >
> > Thank you. This is exactly the sort of use-scenario description that
> > I was hoping to elicit with my post.
> >
> > Two additional <ComponentFont> attributes should be added:
> >
> >   ScaleFactorX
> >   ScaleFactorY
> >
> > Regards...
> >
> > -- Ken
> >
> > On 2009/08/14, at 15:58, Daniel Strebe wrote:
> >
> >> Ken,
> >>
> >> Thanks for wading into this.
> >>
> >> I think we should look at Adobe InDesign's scaling in more detail.
> >> What InDesign provides relevant to this discussion is:
> >>
> >>      * Adjust baseline of a component font.
> >>      * Scale glyphs in a component font horizontally.
> >>      * Scale glyphs in a component font vertically.
> >>      * Scale glyphs in a component font uniformly with respect to  
> the
> >> glyph's center while preserving its width.
> >>
> >> You cannot fully replicate both semantics by dropping any of the
> >> three
> >> provisions. The purpose of (2) and (3) is to adjust a component  
> font
> >> whose glyphs normally run along some baseline, such as Latin-script
> >> or
> >> Indic-script fonts. The adjustment applies to the glyph outline as
> >> well as its horizontal and vertical advance. The purpose of (4)  
> is to
> >> adjust a component font whose glyphs run along a center line,  
> such as
> >> Chinese ideographs. The adjustment applies to the glyph outline but
> >> not its horizontal or vertical advance.
> >>
> >> To elaborate, in Latin-script composite fonts, it is common to  
> scale
> >> glyphs of a component font horizontally, and this scaling typically
> >> applies to all behavior of the font: the amount of horizontal space
> >> the glyph takes up, kerning amounts, escapements. In ideographic
> >> fonts, normally ideographs are considered fixed-width for  
> typographic
> >> purposes, and you do not want mixed widths regardless of which
> >> component fonts the glyphs came from. Yet meanwhile you must  
> balance
> >> the space of the ideographs for two or more different source fonts,
> >> each of which has a different idea of "color" for the font.
> >> (Color, meaning, the amount of whitespace consumed by the "average"
> >> glyph in the ideographic repertoire.) Therefore you scale from the
> >> center of the ideographic box but leave the metrics alone.
> >>
> >> The reason InDesign allows both forms of scaling is because (4) may
> >> be
> >> required to balance the color, while (2) and/or (3) may be required
> >> to
> >> adjust for a non-square construction of the fixed-width ideographic
> >> glyphs. While square in most fonts, especially in the past, some  
> are
> >> not, and this practice is increasing. Hence, it is not so exotic
> >> for a
> >> well-constructed composite font to require all of (1), (2), (3),  
> and
> >> (4).
> >>
> >> Regards,
> >>
> >> - daan Strebe
> >> Senior Computer Scientist
> >> Adobe Systems Incorporated
>
>
> .
>
>
>
>