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RE: Announcing new font compression project

From: Levantovsky, Vladimir <Vladimir.Levantovsky@MonotypeImaging.com>
Date: Mon, 2 Apr 2012 16:41:45 +0000
To: Chris Lilley <chris@w3.org>, Jonathan Kew <jonathan@jfkew.plus.com>
CC: "www-font@w3.org" <www-font@w3.org>
Message-ID: <79E5B05BFEBAF5418BCB714B43F441990C5B7B@wob-mail-01.agfamonotype.org>
On Monday, April 02, 2012 12:25 PM Chris Lilley wrote:

> JK> I think there would be merit in separating - both for discussion and
> JK> in implementation - the two logical stages that are being done here.
> 
> I agree. 'Lossless' can have various meanings, depending on what one
> considers important.
> 

I agree, this is something we need to discuss. The proposed compression is "lossless" in a perceptual sense as the functionality of a font that has been compressed and decompressed is preserved 100%. However, due to data optimization steps that are taken by the compressor to reduce data size, the binary input and output files aren't likely to be identical. In essence, the functionality of the compressor can be loosely compared to an optimizing compiler - the same source code compiled with different optimization levels (e.g. with or without DEBUG option, etc.) would produce executable binary files that are not binary-identical but have 100% guaranteed, identical functionality.

<snip/>

> WOFF 2.0 compression requires an optimised font as a starting point and
> is then lossless.
> 

I am not sure we'd have to go this far and require optimized font as a starting point. The optimization will come naturally as an added benefit, but I agree it needs to be discussed and probably captured in the spec in sufficient details.

> There might be merit in defining a 'visually lossless' concept but I
> suspect that might be hard to define rigorously.
> 

Another alternative would be a 'functionally lossless' concept and it may be easier to define.

Thank you,
Vlad

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> --
>  Chris Lilley   Technical Director, Interaction Domain
>  W3C Graphics Activity Lead, Fonts Activity Lead  Co-Chair, W3C
> Hypertext CG  Member, CSS, WebFonts, SVG Working Groups
> 
Received on Monday, 2 April 2012 16:42:16 UTC

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