bugThe FreeType Project - Bugs: bug #20801, asymmetric glyph rendering in HEAD

 
 

bug #20801: asymmetric glyph rendering in HEAD

Submitted by:  ajaxas <ajaxas>
Submitted on:  Fri 17 Aug 2007 03:57:29 PM UTC  
 
Severity: 3 - NormalItem Group: Incorrect behaviour
Status: ConfirmedPrivacy: Public
Assigned to: Werner LEMBERG <wl>Open/Closed: Open
Planned Release: None

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Thu 22 May 2008 11:55:54 AM UTC, comment #5:

As I said, the problem with the horizontal strokes has been solveed somewhere at the same time this error occurred - it's just I never posted a proper bug report. Though I wrote into ft-devel a couple of times. I even attached two screenshots, now adding them here (let's fix hinting for Cyrillic as we're already here).

Yes, the problem is with this descender, and yes, with freetype-2.3.4 hinting was OK.

Look at the two screenshots of gajim, you will see name 'Александр' in the roaster. Looks like the 'р' glyph is too close to the 'д' on the second one.

PS: sorry for this mess instead of a proper bug report, I will try better next time...

(file #15695, file #15696)

ajaxas <ajaxas>
Thu 22 May 2008 06:09:46 AM UTC, comment #4:

If I understand you correctly: The problem is the missing right descender in letter `д' at certain resolutions, right? Looking at the first image in this bug report, I couldn't deduce this. You were talking about `horizontal strokes', and this confused me.

Before extending the `Latin' autohinter module to cover Cyrillic too, the hinting was fine? It should be easy to adjust.

Werner LEMBERG <wl>
Project AdministratorIn charge of this item.
Thu 22 May 2008 01:15:56 AM UTC, comment #3:

Look at the screenshot I just added.

ajaxas <ajaxas>
Thu 22 May 2008 01:07:39 AM UTC, comment #2:

I've sent you an email earlier, seems like I didn't grasp the situation, sorry :)

I'll quote it here:
=================================================================

It's not bug #20801 (which seems to be solved). I wrote a couple of times about
another bug concerning rendering certain Cyrillic characters, sush as "д".

I will cite myself then:

-------------------------------------------------------------------------------

> As I wrote several months earlier [:)], there's a problem with rendering of
> Cyrillic glyph 'д' with Tahoma (and AFAIR with other M$ Windows fonts as well).
> I'm attaching two screenshots of my desktop - sorry they are so big, but you can
> see the difference when you switch from one to another (look at highlighted
> 'Александр' in the Gajim window). Seems like 'р' is being put too close to the
> previous glyph...
> Though overall rendering is better with 2.3.5.
>
> Regression testing gave me the date when the bug was introduced: 2007-06-15,
> so I hope solving the issue is gonna be a bit easier for you, devs. :)
>
> My configuration is:
>
> rendering - best shapes
> resolution: 96 dpi
> smoothing: grayscale
> hinting: medium
>
> using the autohinter.

------------------------------------------------------------------------------

I have to clear the things out a bit:
First, this applies not only to Tahoma, but for linux original Sans font as
well - at certain resolutions, I think.
Second, seems like it's not this commit that broke font rendering:

> 2007-06-15 Dmitry Timoshkov <dmitry@codeweavers.com>
>
> * builds/win32/ftdebug.c: Unify debug level handling with other
> platforms.


- because this one is pretty much innocent.

I think it must be this commit:

> 2007-06-14 Werner Lemberg <wl@gnu.org>
>
> * src/autofit/aflatin.c (af_latin_uniranges): Expand structure to
> cover all ranges which could possibly be handled by the aflatin
> module (since the default fallback for unknown ranges is now the
> afcjk module). It might be necessary to fine-tune this further by
> splitting off modules for Greek, Cyrillic, or other blocks.

ajaxas <ajaxas>
Sun 18 May 2008 08:19:43 PM UTC, comment #1:

Sorry for the late reply.

What exactly is the problem? For me, the rendering result in the image you've uploaded looks fine (except the letter `I' which is probably hard to fix).

Please test again with the current CVS and be more specific.

Werner LEMBERG <wl>
Project AdministratorIn charge of this item.
Fri 17 Aug 2007 03:57:29 PM UTC, original submission:

System: Ubuntu 7.04
Kernel: 2.6.22.3 (vanilla)
libc: libc-2.5
gcc: 4.1.2 (Ubuntu 4.1.2-0ubuntu4)
ld: 2.17.50 20070103 Ubuntu
as: 2.17.50 20070103 Ubuntu

Video card: NVidia GF-7300GT 256MB
Video driver: NVIDIA-Linux-x86-100.14.09-pkg1

freetrype2 HEAD

When using autohinter, glyphs that have horizontal strokes are rendered asymmetrically at some resolutions. Confirmed with several winfonts (Tahoma, Lucida Sans).

The attached image displays the problem. Image info:

Font: Tahoma (regular)
Resolution: 96 dpi
Font size: 14
Font rendering: best shapes
Smoothing: grayscale (CRT monitor)
Hinting: medium

ajaxas <ajaxas>

 

(Note: upload size limit is set to 16384 kB, after insertion of the required escape characters.)

Attach File(s):
   
   
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Attached Files
file #15695:  ft-2.3.4 (right).png added by ajaxas (35kB - image/png)
file #15696:  ft-2.3.5 (wrong).png added by ajaxas (34kB - image/png)
file #15693:  Screenshot.jpg added by ajaxas (204kB - image/jpeg - An example of strokes gone missing)
file #13680:  tahoma.png added by ajaxas (12kB - image/png - an example of incorrect glyph rendering)

 

Depends on the following items: None found

Items that depend on this one: None found

 

Carbon-Copy List
  • -unavailable- added by pmw
  • -unavailable- added by wl (Posted a comment)
  • -unavailable- added by ajaxas (Submitted the item)
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    Follow 9 latest changes.

    Date Changed By Updated Field Previous Value => Replaced By
    Tue 18 Aug 2009 10:55:00 AM UTCpmwCarbon-Copy-=>Added -unavailable-
    Thu 22 May 2008 05:16:51 PM UTCwlStatusNeed Info=>Confirmed
    Thu 22 May 2008 11:55:54 AM UTCajaxasAttached File-=>Added ft-2.3.4 (right).png, #15695
      Attached File-=>Added ft-2.3.5 (wrong).png, #15696
    Thu 22 May 2008 01:15:01 AM UTCajaxasAttached File-=>Added Screenshot.jpg, #15693
    Sun 18 May 2008 08:19:43 PM UTCwlStatusNone=>Need Info
      Assigned toNone=>wl
    Fri 17 Aug 2007 03:57:29 PM UTCajaxasAttached File-=>Added tahoma.png, #13680
      Carbon-Copy-=>Added ajaxas

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