Font Forge and adding font weight for Kobo?

[Alanon]

I've been on the lookout for nice fonts since the day that I got my Kobo. I've pretty much been on the excellent ChareInk since the moment I discovered it, but I still enjoy looking up and testing fonts that seem promising. I like some serif goodness in my fonts, but an occasional slab can also be appealing. Anyway, after harassing my friend well and good, I managed to badger him into giving me the full set of those nice-looking "eText" font redesigns that were released a few years back. From the marketing spiel, I was hoping that they would be almost ideal for eInk, due to the "super special" technology that was supposedly used in crafting them.

While I actually love the look and feel of all the fonts - spacing, line height, etc, I honestly wouldn't change any of it - the weight leaves something to be desired. Though not nearly as bad as Adobe's Garamond or Jenson (perfect, beautiful fonts, if only they were not so... spidery on my Aura One), they are still a bit on the thin side. The heavier fonts like Galliard could use about 10-15% more weight to reach perfection. To top it off, about half of the fonts had bad PANOSE settings, which was apparent in the selection menu. So I set out to learn how to fix these things. I tried Koboify Fonts 0.3.1 and the latter Readify Font scripts - both refused to embolden the fonts, and in some cases even failed to alter PANOSE settings. (Note, this might have been a consequence of different Font Forge versions - to be certain that the scripts would work, I used the 2015 and 2016 versions respectively, as those were the versions active when the scripts were written.)

Finally, I gave up on the scripts, opened up the latest release of Font Forge for the very first time and decided to do it all manually. Oh boy, what a garbled mess that thing is. I was able to correct the PANOSE settings, but again the added weight did not work. To add the weight, I simply selected all the glyphs and added some weight in the Element - Style - Change Weight - Embolden by, and left everything else alone. Besides this, the only things I've touched were the font names and PANOSE settings - all other errors were usually ignored. I saw the glyphs become heavier while they were processing, and the files ultimately generated properly. To make things even more confusing, once I figured out that there was a problem, I tried to substitute a medium and medium italic font for the regular ones by renaming the set properly, hoping that that would result in a change - it did not. The regular font remained the same weight, and the italic font became regular bold. (Throughout this process, I made sure to check for leftover Kobo font or reading settings, custom sharpness or weight values.)

It may very well be that these fonts have some special tables that prevent the emboldening to appear on my device? I've placed the typical warnings I get when tinkering in Font Forge in the spoiler below, and I've summarised some of the errors that crop up when adding weight. I've tried experimenting with removing the errors, auto correcting and ignoring them, to no avail.

Spoiler:

The following table(s) in the font have been ignored by FontForge
Ignoring 'ADFH'
Ignoring 'DSIG' digital signature table
Ignoring 'VDMX' vertical device metrics table
Ignoring 'hdmx' horizontal device metrics table
This font contains both a 'kern' table and a 'GPOS' table.
The 'kern' table will only be read if there is no 'kern' feature in 'GPOS'.
Warning: Mac and Windows entries in the 'name' table differ for the
Fullname string in the language English (US)
Mac String: Galliard eText ITC ITC
Windows String: Galliard eText ITC
The glyph named Omega is mapped to U+03A9.
But its name indicates it should be mapped to U+2126.


After modifying the weight, I would also get errors in some of the font points citing "You have changed the point numbering of glyph XY... Instructions in this glyph (or one that refers to it) have been lost".

When generating the font, I'd get "Self Intersecting, "Missing points at Extrema", "Wrong direction", "Non-integral coordinates", and "Bad Point Numbering" errors, that I ignored.

Based on my random tinkering, not ignoring some of these completely garbles question marks and the like.

I've no idea what these errors mean or if they're critical or not. I have no clue what to try next and I'm very close to throwing in the towel and using Galliard as-is, which leads me to the question for all you knowledgeable font nerds around here. Am I doing it wrong? Is there some additional step in Font Forge that I missed, which might cause the changes to go wonky? The errors I've tried to describe might mean something to someone, at least enough to point me in the right direction.

I appreciate you sticking with my long-winded narrative, and I'd also appreciate any thoughts you might have on where to go from here!


As an aside, I've included screenshots of all the eText fonts I have installed. In case you were thinking of, or still considering, getting any of them, you can see if they're worth it. One thing I can say, they look substantially... more substantial on the screenshots than on the device itself. Note that there are more fonts in the pack (like Amasis, Malabar, Caecillia, etc.), but they overlap with what comes default with Kobo, and there seems to be some interference there, so I can tell you nothing about them.

[Sirtel]

Kobo has an inbuilt weight adjustment slider. Why not use that? It gives better results than doing it with FontForge.

[Alanon]

That was my initial thought, until I read the opposite on several places in the forum - that Font Forge's algorithm yields better quality than Kobo's built-in setting and preserves more of the font's qualities than Kobo's solution. I have no basis for claiming this (especially not since I wasn't able to embolden the fonts to see for myself), other than the people who claimed this seemed quite versed in typography.

I had also planned on seeing whether or not there are any visible changes to removing the fonts' kerning and hinting, as well as removing PANOS entries with the program. Given that I was going to mess around with Font Forge anyway, it made sense to try and use it for adjusting the weight. I also find editing the fonts has an added benefit, as I can just set them up and not think about it, I can backup the fonts and store them for a day that I might not use Kobo devices.

[NiLuJe]

It's going to be a mess no matter which way you go, especially with heavily (truetype) hinted fonts, as these appear to be.

If there are CFF variants available, these may be less prone to fits of madness (in general, CFF > everything else, as FreeType is using code contributed by Adobe, and Adobe are pretty much the only people on earth doing font rendering mostly right by default).

[AnimalOfArt]

Originally Posted by NiLuJe

It's going to be a mess no matter which way you go, especially with heavily (truetype) hinted fonts, as these appear to be.

If there are CFF variants available, these may be less prone to fits of madness (in general, CFF > everything else, as FreeType is using code contributed by Adobe, and Adobe are pretty much the only people on earth doing font rendering mostly right by default).

OpenType (OTF) is using the CFF, right?

[NiLuJe]

In most cases, yeah.

But, you can *technically* put TTF curves in an OTF.

Meaning, if a font is offered *both* as a TTF and an OTF, then, yeah, the OTF will probably be using CFF.

If it's only offered as an OTF, all bets are off. Except if it's a variable font, in which case it's probably CFF, too. Not that your eReader would know what to do with a VF though ;p.

[sherman]

I've come to the conclusion that the OpenType font specification is an utter mess.

It seems the big tech companies like Apple, MS, Adobe, IBM all decided to create a universal font spec, and instead of going away and creating a new font spec from scratch, or even carefully selecting the best bits from various formats, it seems that most of the features from most of the existing formats were dumped into a pot, stirred around a bit, and out came OpenType.

And yeah, an OpenType font can contain TT or CFF outlines, and the file extension is more of a polite suggestion as to what it might contain.

[JSWolf]

Originally Posted by Alanon

That was my initial thought, until I read the opposite on several places in the forum - that Font Forge's algorithm yields better quality than Kobo's built-in setting and preserves more of the font's qualities than Kobo's solution. I have no basis for claiming this (especially not since I wasn't able to embolden the fonts to see for myself), other than the people who claimed this seemed quite versed in typography.

I had also planned on seeing whether or not there are any visible changes to removing the fonts' kerning and hinting, as well as removing PANOS entries with the program. Given that I was going to mess around with Font Forge anyway, it made sense to try and use it for adjusting the weight. I also find editing the fonts has an added benefit, as I can just set them up and not think about it, I can backup the fonts and store them for a day that I might not use Kobo devices.

You just need to patch your Kobo to enable the Advanced Font Control for allowing side loaded TTF fonts to have the weight adjusted. Then you can test for yourself which you like better.

But the issue with doing it with Fontforge is that you may have to keep going back and forth to get it the way you want. With the Kobo way, it's just a slider that shows you as you change the slider.