PW1 and Kerning

[mandy314]

my rig: PW1 with 5.3.9 FW jailbroken and USE_ALT_FONT mod via fontconfig (hidefont.cfg and alternate.cfg)
(thank you to all who do these things and share them )

the font I use (Amasis MT) has some pronounced kerning pairs (We / Yo etc) and I'm sure there is no kerning on the PW1
with the stock Palatino I'm not as sure but I would say there is no kerning too

so my question: is there an option to enable kerning for the PW1 (stock and/or custom fonts)?

after long deliberation I even tried the fonthack but with all FT overrides I couldn't get kerning
FT should be able to do this I think

BTW: I use the alternate.cfg to enable Antialiasing and disable Font Hinting and I'm very pleased how the fonts look (font size 3-4)

[HeyPretty]

[Katsunami]

I don't know if this is fixable. I've never seen kerning problems with the inbuilt fonts, but I have seen some with several custom fonts. For example, Charis SIL Modified (which floats around this forum) has a pronounced problem if a word contains an i. A word such as "him" looks like "h im" (but with smaller white space), while "intimidating" looks like " int im idat ing".

[mandy314]

thank you for your replies ... and lol

@Katsunami
I have Charis SIL Compact direct from the SIL Homepage. This font has no kerning information (ie the kerning table is empty). I don't know about the Modified version you mention. But the letterspacing issues you describe could be (if there is no kerning) a problem of font hinting. Hinting alters the glyph outlines afaik which may result in not so nice letter spacing.

With 200+ dpi and anti-aliasing the PW isn't really high resolution but it isn't low-res either. I have disabled Font Hinting and have "true" glyph outlines (and "good" letterspacing) for the cost of some edge-enhancement. All this is a matter of taste and in the eye of the beholder imho.

Here is my simple alternate.cfg - this works for all fonts

<?xml version="1.0"?>
<!DOCTYPE fontconfig SYSTEM "fonts.dtd">
<fontconfig>
	<match target="font">
		<edit name="antialias" mode="assign">
			<bool>true</bool>
		</edit>
		<edit name="hinting" mode="assign">
			<bool>false</bool>
		</edit>
	</match>
</fontconfig>

what I'm hoping for is an expert (and there are so many here) saying: yeah with some patches of system files /or/ yeah with a FT override we may be able to turn Kerning on
I would be very glad indeed ...

[Katsunami]

It is possible in Linux, when using unofficial versions of FreeType. These versions have better anti-aliasing and kerning algorithms that are not in the official FreeType.

I do not know if the Kindle uses FreeType and if it does, if you could replace it. I'm a software engineer, but I'm not into Kindle hacking.

[mandy314]

thanks again
I've added an image to illustrate what I hope is achievable
four fonts (Palantino, Amasis, Concorde, Charis): first line no kerning / second line with kerning
except for Charis (which has no kerning information) for some letter-combination the spacing is altered with kerning
the glyphs are "overlapped" or "undercut" - Yo and VAT are the best examples

as I said: I'm not sure but for me it looks like the PW doesn't do any kerning for stock and custom fonts

[NiLuJe]

@mandy314: I can't speak for Amazon's FT implementation, since I pretty much got rid of it on every device except my K4, but I'm pretty sure the KF8 reader (if not the legacy M7 one too) should handle kerning (since it's basically FT+FC+Pango).

That said, I'll check that more throughly tomorrow, because the whole font rendering/script layout stack of the Kindle sometimes does crazy things for no apparent reason .

EDIT: Hmm, I might have been dreaming that. Or remembering old tests w/ a different ft build/font, because, yup, no kerning w/ my current setup. Will check in detail tomorrow.

[mandy314]

thank you for all the information
further tests (for the kf8 reader) ... that sounds great

in the meantime I learned from the FT website that FT doesn't do kerning (they say FT is a glyph based service, all spacing stuff must be done by a higher level) (btw for a non-linux person all the builds, patches etc are quite confusing)

and a small amendment for the "turn off all hinting" lark
to make really sure you may use this in the alternate.conf
(a further option could be to disable hinting for bold fonts only)

<?xml version="1.0"?>
<!DOCTYPE fontconfig SYSTEM "fonts.dtd">
<fontconfig>
  <match target="font">
    <edit name="antialias" mode="assign"><bool>true</bool></edit>
    <edit name="rgba" mode="assign"><const>none</const></edit>
    <edit name="lcdfilter" mode="assign"><const>lcdnone</const></edit>
    <edit name="embeddedbitmap" mode="assign"><bool>false</bool></edit>
    <edit name="autohint" mode="assign"><bool>false</bool></edit>
    <edit name="hinting" mode="assign"><bool>false</bool></edit>
    <edit name="hintstyle" mode="assign"><int>0</int></edit>
  </match>
</fontconfig>

[NiLuJe]

@mandy314: Yup, that would be the job of the script layout engine. Pango, in the KF8 reader case .