Re: Support for Vector Images

Chris Lilley (Chris.Lilley@sophia.inria.fr)
Sun, 30 Nov 1997 22:46:31 +0100 (MET)


Date: Sun, 30 Nov 1997 22:46:31 +0100 (MET)
From: Chris Lilley <Chris.Lilley@sophia.inria.fr>
Message-Id: <9711302246.ZM10793@grommit.inria.fr>
In-Reply-To: Peter Flynn <pflynn@imbolc.ucc.ie>
To: Peter Flynn <pflynn@imbolc.ucc.ie>, www-html@w3.org
Cc: chris@w3.org, www-style@w3.org
Subject: Re: Support for Vector Images

On Nov 28,  2:34pm, Peter Flynn wrote:

> EPS is not necessarily vector-based, it can contain bitmaps too.

As can most vector formats (although not necessarily with great efficiency)

> The best choice would be CGM,

I agree that this is a fine choice in some circumstances; it is not a
universal panacaea though...

> which is the international standard

So is SPDL. Being an ISO standard is not, of itself, sufficient reason
for choosing a format. It's nice to have, especially where this enhances
portability by reducing the number of incompatible variants. In the case
of CGM, mutually incompatible variants are a known problem and result in
the need for profiles to ensure mutually comprehensible interchange.

Unfortunately, packages often have weak support for writing to a
particular named profile.

> and is
> supported in most vector graphics packages

To an extent - many support exporting as level 1 CGM, with no particular
guarantees of creating a valid metafile or even of being able to read
the same file back in without loss. Support for level 3 CGM, which is
where you get all the good stuff like curves, stencilling, control over
line termination and mitring, is patchy at best. I am always happy to
hear about programs with good CGM import and export facilities, BTW.

> (and even in some bitmap
> ones).

Although if all the original information is rasterised, saving as CGM
buys you little except wildly increased storage size (rather like EPS
in that respect ;-)

> SGML browsers like Panorama and MultiDoc Pro already support
> it.

Panorama I already know about, tell me more about MultiDoc Pro (in
private mail, if you wish). There are also assorted plug-ins for
Netscape, MSIE, Amaya etc which implement CGM (generally level 1
support with a smattering of level 3 features).

> But the W3C can recommend until they're blue in the face: if
> browser makers don't see $$$ in it, they simply won't bother.

True (and note that CGM is not a formal W3C Recommendation). We do have
a NOTE about it [1] and it certainly shows promise as a vector format for
the Web, with some work on profiles and hotlinking functionality.
It may even be possible to inherit CSS style information into the CGM
using bundle tables (he said noticing the CC list).

[1] http://www.w3.org/TR/NOTE-cgm


-- 
Chris Lilley, W3C                          [ http://www.w3.org/ ]
Graphics and Fonts Guy            The World Wide Web Consortium
http://www.w3.org/people/chris/              INRIA,  Projet W3C
chris@w3.org                       2004 Rt des Lucioles / BP 93
+33 (0)4 93 65 79 87       06902 Sophia Antipolis Cedex, France