Font Rendering, etc.

Asked by linuxsapien on 2011-06-05

First things first, I am glad to be part of this, even if I am probably of not much use. Ill try my best to poke around..

I have been more than impressed with these installed fonts. The recent addition with a mono font is obviously very exciting for us Ubuntu users. As well as it holding the brand together so well, personally I find it a very pleasing and beautiful type-face!

My question, or query is:

What font rendering technique is suited best. Obviously by default we have sub-pixel, but there are three other techniques to use if so desired. However in sub-pixel we are able to change smoothing, hinting and order also.

at the mo, I have it set at sub-pixel smoothing, full hinting and VRGB order. Resolution is as always, kept at 96.

Thank you.

Question information

Language:
English Edit question
Status:
Solved
For:
Ubuntu Font Family Edit question
Assignee:
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Solved by:
Paul Sladen
Solved:
2011-06-06
Last query:
2011-06-06
Last reply:
2011-06-06
Best Paul Sladen (sladen) said : #1

Hello linuxsapien: regarding pixel-ordering, it is possible to give a purely technical answer—it needs to match your physical display. Most TFT screens available at (and even Sony Trinitron CRT monitors) have horizontal RGB ordering in their default orientation.

This exact setting is important on a tablet or netbook (where the display might be the "wrong way" up). If the machine's display is rotated by 180-degrees then the ordering of the sub-pixels becomes blue-green-red (BGR). You can check this using a magnifying glass.

If the same netbook or tablet display is used in portrait mode then the ordering would be either vertical-RGB or vertical-BGR (depending on which orientation). Having the wrong setting for sub-pixel is ever worse than having no setting at all.

Hinting is the amount of intentional distortion applied to the characters, in order to bend them to align to the low-resolution pixel grid. No hinting (no distortion) is closer to what Apple use (which some people might say is blurry, but natural as a result). Full Hinting are the human-defined distortions created by the font designer and is closer to MS Windows' rendering (which some people might say leaves the fonts distorted, or sharp).

Slight hinting does not use the manual hints, but instead uses an automatic algorithm that applies distortion only in the vertical positioning; this is the default that Ubuntu currently uses.

Resolution (dots-per-inch) should ideally be set to the settings reported by the monitor; unfortunately most software does not cope with scaling properly and so leaving it at 96 DPI is a very common practice.

linuxsapien (linuxsapien) said : #2

Thank you very much for taking your time to explain this in detail. Its more than I expected, so if I could add a wee dram to "this solved my problem. Then I would.

Slainte.

Nikolaus Waxweiler (madleser) said : #3

Speaking of rendering, is there any possibility of switching to unhinted font display by default using www.infinality.net's FreeType patches? See my example pictures at http://imageshack.us/g/594/bildschirmfotoam2012031.png/ -- I'm using OSX mode and like the undistorted display :) Has the nice side effect of all fonts looking slick without hinting while remaining readable. Basically, what's done on Mac OS X.

Paul Sladen (sladen) said : #4

Hello Nikolaus. It might be good idea to raise this as a separate question so that we don't risk diluting the question above (see below).

For several years in Ubuntu we've been shipping with patches—and an assoicated default configuration—that applies a level of sub-pixel anti-aliasing, along with some vertical-only hinting. This is perhaps "a middle way" between what other common operating systems are doing by default. A somewhat simplified overview would be:

  a. "Mac", no hinting (no distortion). To a Windows user this tends to appear "blurry". To a Mac user it looks "accurate".
  b. "Ubuntu", vertical hinting (vertical distortion). This is somewhere in the middle.
  c. "MS Windows", hinting (distortion) in both horizontal and vertical. To a Mac user this looks distorted. To a Windows user it looks sharp.

(* The exact rendering settings continue to vary slightly with new releases of various operating systems).

The best thing to do would be to open a new bug report with a suggestion documenting exactly which options/settings you believe would be an improvement for future versions of Ubuntu, along with before/after screenshots. This would allow a wider range of people to talk part in a discussion. It would certainly be good to have another look at what we can do to make people's reading experiences even better.

Nikolaus Waxweiler (madleser) said : #5

Alright, will do when I get the time. Thanks for your long explanation :)