[Xenophon]

Originally Posted by thibaulthalpern

I'm not talking about a change in underlying document format. I'm talking about why at this point PDF still trumps ePub format when talking about faithfulness to design.

Of course PDF provides better fidelity to design -- that has always been it's prime purpose! All the accessibility and reflow features arrived later as afterthoughts.

Originally Posted by thibaulthalpern

It shouldn't be up to the software display program to determine whether the "fi" should be ligatured. This should be a decision made by the human who creates the document. There are instances when "fi" should NOT be ligatured because the font is inappropriate to do so, or the presentation of the text does not call for ligatured glyphs. In certain scientific technical documents, I don't see ligatures being useful.

Well, the standard Mac software provides the necessary interfaces to let the user control both default choices about ligatures and also any specific instance of the appearance (or non-appearance) of a ligature. My main point was that the default settings generally do quite nicely. It does seem to me, however, that a properly designed font should include the ligatures that are appropriate for that font, and should omit any ligatures that are inappropriate. And the advanced typography support doesn't conjure up ligatures out of nowhere -- it selects only from among the ligatures that are present in the font being used.

As for scientific technical documents, I prefer to have (standard) ligatures in running text -- they make it easier to read. I suppose that some of the most decorative and extreme ligatures might not belong there. On the other hand, ligatures clearly do not belong in formulae or source code. But I can trivially make this choice via the standard display settings (for default, styles, etc.).

Originally Posted by thibaulthalpern

If we are depending on reader software to determine whether ligatures should or should not happen, it's like the problem with Microsoft Word's autoformat which is unfortunately mostly a hinderance because it cannot interpret the context in which we are working in and thus does not know whether we want something formatted in x-style or y-style.

The current state of the art in software certainly fails to make the correct choices without some user input. But for most fiction (for example) a single default setting handles 99.9% of the book -- that is, all the running text. And even titles probably look better with the standard simple ligatures. Further, the state of the art in software continues to improve over time.

Originally Posted by thibaulthalpern

The reason PDF trumps other digital formats that I know of is precisely because of its superiority in display presentation. That's basically it for me. The PDF format doesn't determine whether some is kerned so or ligatured so, because it's all set up by the human being (or the human-software interaction) PRIOR to the creation of the PDF.
[SNIP a bunch of good text about the PDF format]

That's all true -- as long as the display used for the presentation is the same as the designer's intended display.

But while ligature choices likely should survive size-changes and reflow, I'm far less certain about kerning. And the vast bulk of the rest of the careful human design for layout is usually, well, wasted when my viewing display differs substantially from your intended layout in terms of size, aspect ratio, DPI, contrast, color (or lack thereof), etc.

For example, there are plenty of fonts that are absolutely gorgeous when printed at 1200DPI but are unreadable on my ~180DPI Sony PRS-700 -- even when the physical measurements of the characters are identical! And your beautifully hand-tuned layout for an 8.5"x11" page (or A4 page!) won't work well on my 6"-diagonal reader.

On the other hand, the current presentation of auto-reflowed formats such as ePub is often significantly lacking as well. We have poor support for full justification (with embarrassingly hideous rivers of white-space), lousy or just plain missing auto-hyphenation, no ligatures ever, and on and on.

The point I've been trying to make here (at far too much length) is that when reflow is required PDF is even worse than formats like lrf or ePub. Meanwhile the reflow-able formats don't display as nicely as a well-designed hand-optimized document (which must be presented via PDF, or Postscript, or an image file of some sort or...).

The different kinds of formats have different strengths and weaknesses. As auto-layout and presentation software gets better, the reflow-able formats will look better and better. As auto-reflow from PDF gets better, that nice hand-optimized layout will degrade less and less for other page sizes. But today, PDF is the right choice for fixed size and nearly hopeless for reflow. And lrf/epub/etc. are decent for reflow, and ugly for fixed-size presentation.

You pays your money and makes your choice. One format does not yet fit all!

Xenophon