Re: [ft-devel] Peculiar Hinting / Rendering Behavior

[Werner LEMBERG]

Hello Darrell!


> I am using freetype 2.5.0 and have encountered an interesting
> rendering artefact around hinting.

It's not related to hinting...

> I am using the Microsoft "MS Mincho Regular" true type typeface
> (msmincho.ttc) found with Windows 8:
>
> ftview -m "四" -r 150 9 msmincho.ttc
> (that's character 0x56db for the message)
>
> When the viewer loads, do two things:
> (1) Hit 'b' to turn embedded bitmap strikes OFF.
> (2) Hit 'a' to turn anti-aliasing OFF
>
> In my version of ftview, following these two steps results in the
> left vertical bar of the character to go missing.  What I find to be
> rather interesting is that when I hit the 'h' key to turn hinting
> OFF in ftview, then the left vertical bar of the glyph returns!

Here's another recipe to see the artifact even better (I'm using
msmincho.ttc from Windows 7):

  ftgrid -f 4420 19 msmincho.ttc

(value 4420 is the glyph index of U+56DB in this font).  After
pressing key `a', a vertical line on the left is missing in the
outline.  Interestingly, this happens at 100% zooming only.

I've poked around a bit, but I'm still clueless which component causes
this.  This needs more debugging, so it may take a while until I find
time for that – it's one of the weirdest rendering problem in FreeType
I've ever encountered :-)


    Werner