[XeTeX] Devanagari rendering with XeTeX - a comparision

[Jonathan Kew]

On 6 Jan 2010, at 18:10, Deepak Jois wrote:

> Hi All
> 
> I have been using XeTeX to test the rendering of Devanagari using
> different fonts and layout engines. Here is a sample containing
> multiple renderings of a word from the Rig Veda.
> 
> Sample Rendering :
> http://farm3.static.flickr.com/2755/4250942627_469615ffbc_o.png
> 
> TeX source : http://gist.github.com/270468
> 
> The first four are using OpenType fonts (Nakula, Sahadeva, Akshar and
> Gargi respectively). The last one uses Devanagari MT. In my (not so
> expert) opinion, the Devangari MT/AAT rendering while not perfect, is
> superior to the OpenType rendering by a fair stretch.

This is quite simply a question of the font designs. There's no reason an OpenType font need be inferior, but the results depend on the quality of the glyph design and the OpenType tables included in the font.

Devanagari MT is a professionally-designed font from a reputable vendor. I'm not familiar with most of the OT fonts you mentioned, but if they're free fonts, perhaps by amateur designers, it's likely that they are not comparable in quality. It would be interesting to compare the results with Devanagari fonts from vendors such as Adobe, Monotype, or Linotype and see how those look.

> I am mailing
> this list to get some insights about the rendering process, and see if
> anything can be done to improve it for OpenType fonts. Specifically :
> 
> 1. Why is the OpenType/ICU rendering bad, compared to AAT. Is it the
> font, or is it the layout engine, or both? My limited understanding is
> that the Devangari MT font contains glyph layout information within
> itself, as opposed to the OpenType fonts which rely more on software
> to layout the glyphs. Is there an inherent advantage in the font
> containing the layout information, or can software be made to
> replicate a similar quality?
> 
> 2. What can be done to improve this? Are there better fonts? Does a
> later version of ICU (i believe XeTeX uses ICU 4.0) contain any
> enhancements?

There are other fonts "out there"; I'm not qualified to assess which ones are best. (Note that which fonts are "better" may depend on the kind of text you're setting, too. A font might work really well for Hindi, but give poor results for Sanskrit - or vice versa - due to the different letter combinations that occur, and different expectations for glyph forms, conjunct formation, etc.)

> 
> 3. Can anyone tell if Uniscribe on Windows Vista does a better job. I
> would appreciate a sample, since I dont have a Windows system here to
> test it out myself.

The primary issue isn't the platform or the ICU or Uniscribe version, it is the font.

JK