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Re: Problem in understanding relation b/w printer resolution and CSS 'position' attribute

From: Ian Hickson <py8ieh@bath.ac.uk>
Date: Mon, 21 Jun 1999 19:33:16 +0100 (BST)
To: Amit Rekhi <amit@abinfosys.com>
cc: www-html@w3.org
Message-ID: <Pine.GSO.4.04.9906211927560.29384-100000@mary.bath.ac.uk>
On Mon, 21 Jun 1999, Amit Rekhi wrote:

> My problem is not understanding 
> * How the print is coming proper inspite of the my changing the
> resolution from 600 dots to 75 dots per inch?
> * Who is controlling this proper printing of the text inspite of the
> width being fixed and the resolution being changed?

See CSS2, section 4.3.2, which says: 

# Pixel units are relative to the resolution of the viewing device, i.e.,
# most often a computer display. If the pixel density of the output device
# is very different from that of a typical computer display, the user
# agent should rescale pixel values. It is recommended that the reference
# pixel be the visual angle of one pixel on a device with a pixel density
# of 90dpi and a distance from the reader of an arm's length. For a
# nominal arm's length of 28 inches, the visual angle is therefore about
# 0.0227 degrees.
# For reading at arm's length, 1px thus corresponds to about 0.28 mm (1/90
# inch). When printed on a laser printer, meant for reading at a little
# less than arm's length (55 cm, 21 inches), 1px is about 0.21 mm. On a
# 300 dots-per-inch (dpi) printer, that may be rounded up to 3 dots (0.25
# mm); on a 600 dpi printer, it can be rounded to 5 dots.


Note. This is off-topic for www-html. CSS issues should be discussed
in www-style.

Ian Hickson
: Is your JavaScript ready for Nav5 and IE5?
: Get the latest JavaScript client sniffer at 
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Received on Monday, 21 June 1999 14:33:26 UTC

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