Re: Support for Vector Images

Chris Lilley (
Sun, 30 Nov 1997 23:04:36 +0100 (MET)

Date: Sun, 30 Nov 1997 23:04:36 +0100 (MET)
From: Chris Lilley <>
Message-Id: <>
In-Reply-To: "David Perrell" <>
To: "David Perrell" <>, <>,
Subject: Re: Support for Vector Images

On Nov 29,  7:19pm, David Perrell wrote:

> I believe CGM (Computer Graphics Metafile) supports clipping paths.

Yes. It calls the concept stencilling.

> It
> certainly can use bitmaps as texture fill, which is basically the same
> thing. A CGM can contain vector graphics (e.g., polylines,

yes, right from level 1

> ellipses, NURBS),

in level 3 and 4. NURBS with trimming curves gives a considerable degree of
expressive power (the ellipses, conic sections, etc can be considered mere
syntactic sugar for NURBS)

> raster graphics (e.g., tile array), and text.[1]

Yes. The text suffers a bit from lack of downloadable fonts and is a
little I18N challenged but is otherwise okay.

> Postscript is a page description language; an EPS file is actually an
> interpreted program. CGM is a graphics file format. CGM files require less
> processing overhead to display.

The old declarative vs procedural comparison again, which also implies
that CGM is easier to read in, edit a bit, and save back out again.

> They also require less bandwidth to move
> around. I did a comparison of image formats as exports from CorelDRAW!. A
> simple logo was 1.5k bytes as a CGM file. It was 24k as an EPS.

Did this saving carry over to other files, or did you just test a single

Chris Lilley, W3C                          [ ]
Graphics and Fonts Guy            The World Wide Web Consortium              INRIA,  Projet W3C                       2004 Rt des Lucioles / BP 93
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