TTFAutohint: Grayscale / GDI / DW ?

Ramiro Espinoza

Hi there,

Can someone explain (or point a webpage where it is explained) in what occasions it's necessary to choose each or all of the 3 "Strong Stem width and positioning" TTFAutohint options (Grayscale / GDI Cleartype/ DWCleartype) ?
Thanks in advance.

(BTW, I managed to bottle TTFAutohintGUI for Mac with Wineskin :) )

Ramiro Espinoza

I've found: http://www.freetype.org/ttfautohint/doc/ttfautohint.html
but I still don't know when it's better to click GDI and DW together or to leave only GDI (default option).

Jason Campbell

This is a question of market share, from my perspective. Currently Win 8 (using DW) has a smaller share of the market place, so I lean towards GDI, which was used up to Win 7. Likewise, Grayscale's only going to be seen by those with Win XP and Cleartype disabled, which hopefully is a small and shrinking portion of the market.

Ramiro Espinoza

Does it make sense to click the 3 checkboxes?

Thierry Blancpain

I'd say probably GDI for now and DW to make it future-proof – depends on filesizes and usage.

Jason Campbell

Agree with ThierryBlancpain

Werner Lemberg

It's hard to give a recommendation. It really depends on the font.

With some simple shell scripting it's very easy to create a set of fonts using the available combinations of option -w which can then be tested with various browsers on various platforms.

DaveCrossland

Werner, could you provide an example of such a shell script? :)

EbenSorkin

To extend what Werner said the "strong" setting in TTFA is there to indicate that in a give rendering mode you want to have TTFA to err on the side of rendering whole pixels. This makes font stems more solid but there are tradeoffs. The rounds can look overly blocky. The best thing to do is to try browser and OS combinations that let you see/test Greyscale, GDI and DW. Then you can decide of you want to use strong for each instance.

The other point that is worth making because I can see that there is confusion about this is that you are not choosing GDI vs DW. You may have the font render in any of these. You are just setting a strong vs softer setting for each of these 3 instances.

My question is which of these 3 check boxes (if any) is relevant to Freetype rendering. Werner?

jmsole

In Windows, a batch CMD file that should help with testing the different options will look like this:

@echo off
:: set basics
set DESTPATH=%~dp1
IF %DESTPATH:~-1%==\ SET DESTPATH=%DESTPATH:~0,-1%
MD "%DESTPATH%autohint"
if [%1]==[] goto :eof
:loop
set fullfile=%1
set filename=%~n1
goto :MAINACTION
:: do the deed
:MAINACTION
C:\wfont-tools\ttfautohint -G 200 -l 8 -r 72 -c -n -w "" -x 0 -f %fullfile% "%DESTPATH%autohint\%filename%-none.ttf"
C:\wfont-tools\ttfautohint -G 200 -l 8 -r 72 -c -n -w gGD -x 0 -f %fullfile% "%DESTPATH%autohint\%filename%-all.ttf"
C:\wfont-tools\ttfautohint -G 200 -l 8 -r 72 -c -n -w g -x 0 -f %fullfile% "%DESTPATH%autohint\%filename%-grayscale.ttf"
C:\wfont-tools\ttfautohint -G 200 -l 8 -r 72 -c -n -w G -x 0 -f %fullfile% "%DESTPATH%autohint\%filename%-GDI.ttf"
C:\wfont-tools\ttfautohint -G 200 -l 8 -r 72 -c -n -w D -x 0 -f %fullfile% "%DESTPATH%autohint\%filename%-Directwrite.ttf"
C:\wfont-tools\ttfautohint -G 200 -l 8 -r 72 -c -n -w gG -x 0 -f %fullfile% "%DESTPATH%autohint\%filename%-gG.ttf"
C:\wfont-tools\ttfautohint -G 200 -l 8 -r 72 -c -n -w gD -x 0 -f %fullfile% "%DESTPATH%autohint\%filename%-gD.ttf"
C:\wfont-tools\ttfautohint -G 200 -l 8 -r 72 -c -n -w GD -x 0 -f %fullfile% "%DESTPATH%autohint\%filename%-GD.ttf"
shift
if not [%1]==[] goto loop

"C:\wfont-tools\" is where I keep the ttfautohint.exe file. You should replace this with the path where you keep it. This script creates a new folder adding "autohint" to the name and then puts each new autohinted file inside this folder with it's respective name. It's better if you have the source files in a specific folder for it rather than your desktop or something like that. When you've set everything up you simply need to drag and drop your source TTFs on top of the CMD file. Also, it should work for multiple files.

One last thing, the other flags are the ones I usually use. You may want to modify them to your liking.