widths versus heights

[lumpynose]

If I remember correctly an em is the width of a lower case M character. And an ex is the height of a lower case X character. So why do we use em for specifying things that are heights when we should be using ex?

(And don't get me started about the W3C site using the word alternate when they should be using alternative.)

[dwig]

The ancient and arcane art of typesetting and font design is an ancient art and likely was shaped (warped??) by long term exposure to lead fumes and whatever toxins were in the ink. The theft of some of those mystic terms by modern computer wizards is both evil and usually flawed.

That said, x-height is not a measurement, either absolute or relative, until you add some modifier (large, small, ...) and then is only a relative comparison to other aspects of the characters (usually baseline to a vaguely defined line marking the top of most majuscule letters). It is of no real absolute relation to the point size of a font.

Em, on the other hand, refers to a space normally equal to the width of a majuscule (captial, upper case, ...) M, though many fonts define their em space to a slightly different width, especially italic and various ornamental types.

[Hitch]

Originally Posted by dwig

The ancient and arcane art of typesetting and font design is an ancient art and likely was shaped (warped??) by long term exposure to lead fumes and whatever toxins were in the ink. The theft of some of those mystic terms by modern computer wizards is both evil and usually flawed.

That said, x-height is not a measurement, either absolute or relative, until you add some modifier (large, small, ...) and then is only a relative comparison to other aspects of the characters (usually baseline to a vaguely defined line marking the top of most majuscule letters). It is of no real absolute relation to the point size of a font.

Em, on the other hand, refers to a space normally equal to the width of a majuscule (captial, upper case, ...) M, though many fonts define their em space to a slightly different width, especially italic and various ornamental types.

Yes, and if I may hijack this thread a bit, just for a moment, to rant, the idiots who are posting dreck all over the net about how "tall/high x-heights" are better for readability should be hunted down and shot. I now get to hear this repeated often, by print designers who are INSISTING that the fonts that they used in their print design must be used for eBook layout, due to "tall/high x-heights and improved readability."

Even when they look bloody AWFUL/OFFAL.

Or worse, they say, "sure, you can replace it if you think that the font is too light for eInks," but they expect you to kill yourself finding another font with an "equal" x-height (uuuuuhhhhhhh) that will work with their accent fonts, yadda. OH, yeah, 'cuz, EVERY font lists its relative x-height, right? NOOOOOOooooo, folks, they don't, and nor do most font managers. Surprise! (for that matter, other than Typograf, I defy you to find a font manager that even lists the font metrics....and the guy who developed Typograf kind of rolls his own, really. When I tried to get MainType to add font metrics, they seemed to think I was insane.)

Oh, and let's not get into, "oh, yeah, and while we're at it, since we're talking eBooks in a world where not every reader can/will display embedded fonts, you also have to make sure that on a reader that doesn't display embedded fonts, the set font-size for this large x-height font will be something normal, like 1em, not .8 em or 1.4em or whatever, screwing up the book when a default font is used to display the content."

Do we have an emoty for "locking myself in a soundproof room and screaming myself hoarse?"

/rant

Sorry, now back to our regularly-scheduled program.

Hitch

[lumpynose]

This all reminds me of long ago back in the 1980s when we got a laser printer, before Apple started selling them. I can't remember who made ours but it was big and smelled like kerosene. I got a bunch of bitmapped fonts, perhaps from Stanford, but they were for a 200 dpi printer and ours was 300 dpi. The point sizes were part of the name of each font file. I hunkered down and wrote some code to convert them to the file format that our printer used.

I'll always remember how perplexed and amazed I was that the point sizes of a font were just some apparently arbitrary and random number. I.e., that a 9 point Times Roman wasn't the same size as a 9 point Courier.

[dwig]

Offal is right. IMO, large X-height fonts are only suitable in situations where you need to use extremely small text and then only with reasonably large leading, relative to the point size. When the larger leading ("line spacing" in newspeak) is used, the whitespace between lines of body copy remains reasonable and readability is maintained. There may be some actual improvement resulting from the relatively smaller ascenders and descenders and the reduction of visual conflicts between descenders on one line and ascenders on the line below.

For some comic relief, track down a copy of Fredrik Brown's short story ETAOIN SHRDLU, though some basic knowledge of the use of Linotype machines and terms is helpful.