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Re: Pixel densities (was RE: Best practice for font control)

From: Matthew Brealey <thelawnet@yahoo.com>
Date: Wed, 26 Jan 2000 02:58:47 -0800 (PST)
Message-ID: <20000126105848.2231.qmail@web901.mail.yahoo.com>
To: www-style <www-style@w3.org>
--- I wrote:
> In addition, I would recommend a visual angle of 1/2380 rad, since 85ppi
> is  more typical for a  computer display (although I'm sure the 'Windows
> is best' mindset will triumph).

Using 96ppi is deeply misguided, confusing the two things, conversion
factors and true pixel density.

The 96ppi value used by Windows is simply a conversion factor used to
convert from real-world lengths into pixels suitable for rendering. This
has absolutely _nothing_ to do with px as a CSS unit (as used in
font-size: 16px). If there really is a desire to select a value that
resmbles that of the average Joe Windows, it is necessary to have the
following information:

1. screen resolution
2. the physical dimensions of the monitor

This will result in a value that gives the size of a rendered pixel - a
true pixels-to-points value as opposed to points-to-pixels.

This value in no way relates to either the 72ppi or 96ppi used by typical
Mac or Windows systems.

To approximate what the average user has, 85ppi is much more reasonable.

From Matthew Brealey (http://members.tripod.co.uk/lawnet (for law)or http://members.tripod.co.uk/lawnet/WEBFRAME.HTM (for CSS))
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Received on Wednesday, 26 January 2000 05:58:49 UTC

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