[1 mod] Hinting: lowercase w on MS Windows

Bug #801716 reported by Ryan O'Shea on 2011-06-24
This bug affects 2 people
Affects Status Importance Assigned to Milestone
Ubuntu Font Family

Bug Description

Hinting bug on lowercase 'w' on Microsoft Windows 7 Service Pack 1.
Rightmost stroke of lowercase 'w' is squeezed into a near-vertical line, making the letter disproportionate. See attachment for example.
Text displayed rendered with Mozilla Firefox 5.0 (DirectWrite + ClearType). Only happens at a specific size, but across browsers and applications.

Ryan O'Shea (rinoshea) wrote :
Paul Sladen (sladen) wrote :

This has been puzzling me; the debug is reporting 39 PPEM, but it looks more like ~16 PPEM. If it was giving the sub-pixels it would be 13 PPEM.

Interesting to know what the DejaVu PPEM debug reports in the same circumstances.

Changed in ubuntu-font-family:
importance: Undecided → Medium
milestone: none → 1.00
status: New → Triaged
tags: added: uff-hinting uff-latin uff-w uff-win32
removed: hinting windows

I spotted something similar when using the Ubuntu fonts in Google Docs.

 From a quick test in VTT, it appears that it only happens when the MS
Cleartype rasterizer is in B&W-metrics-compatible mode. This is a
surprise, as the changes the rasterizer makes to outlines in that mode
are usually quite subtle. We'll investigate and see if we can adjust the
hints so it "does the right thing" by default.


David: GETINFO bit 7 appears to return if ClearType post-hinting width fix-ups are in use:


if that any use for conditionally doing something else when CT is active?

On 27/06/2011 12:39, Paul Sladen wrote:
> if that any use for conditionally doing something else when CT is
> active?

Yes, it's perfectly possible to have conditional hinting and deltaing
for the various rasterization modes, but we may be able to do it more
simply than that - replacing some horizontal hints with interpolations
etc. that cover more conditions in a single instruction.


Ryan: if you rotate your display to be in portait mode, (ClearType operating in the vertical direction), or you find any other strange issues start to pop up too?

Paul Sladen (sladen) wrote :

David: +1 for having a single codepath from a maintainable point-of-view.

I'm actually having the exact opposite problem under Windows XP. The right-most stroke is at much less steep angle than the rest of they lower case 'w'. I also attached an upper case 'W' that looks good. It appears the lower case 'w' is not hinted correctly.

Attached is from the Ubuntu web page rendered in Firefox 21.0 on XP.

truly (trulyhealthy) wrote :

Letter "w" misbehaving once again.

Some examples:
Font-weight:300 between 16px and 20px;
font-weight:400 between 8px and 20px;
font-weight:500 15px;
under Google Chrome and Safari (appears to work fine under FireFox and IE10).
Windows 7, Cleartype on.

I was forced to change website's css into different weights and/or sizes to show prpoerly.

Paul Sladen (sladen) wrote :

Joe/Truely: Oooh, that is quite exciting. It's definitely an issue; though I had to re-read this after having not focused on it for a couple of years! Thank you for the screenshot.

You said you had to force the Website CSS; could you paste in exactly how/what you found the best way of doing that was (so that whoever is working on debugging it can replicate it in the same way).

truly (trulyhealthy) wrote :

Created simple html to help analyze all weights of different sizes.

The "w" works for some and does not work for others in what appears to be random.

Google Chrome and Safari use a different render, which makes a mess of the "w", compared to FireFox or IE10. Make sure to test on all browsers.

truly (trulyhealthy) wrote :

Added to the above html which particular weight/size/upper-lower shows incorrect in Google Chrome.

truly (trulyhealthy) wrote :

I have to mention the issue with "Ww" is only the right half size of the letter (the right "V" if you wish). The left size seems ok at all weight/sizes.

While we're all here, the letter "v" has similar issues as "w" at about the same weight/sizes.

Also, the letter "M" @ 700 @ 8px 10px 13px, and @ 300 @ 17px 18px looks weird. "M" is the mirror of "W", so probably the same bug.

truly (trulyhealthy) wrote :

Wonder if you have had time to fix the "W" and "w" as mentioned above.
They still look having the same issues:

New issue:
New Google Chrome Version 32.0.1700.76 does not like Ubuntu "Light 300" and shows it as "Medium 500".
You can review at: http://www.google.com/fonts#UsePlace:use/Collection:Ubuntu

Both issues above disrupt the visual quality of any website.

We'll appreciate your time.

summary: - Hinting: lowercase w on MS Windows
+ [1 mod ] Hinting: lowercase w on MS Windows
summary: - [1 mod ] Hinting: lowercase w on MS Windows
+ [1 mod] Hinting: lowercase w on MS Windows
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