Subject: ISSUE: Differential resolutions

From: Graham Klyne <[email-masked]>
Date: Wed, 30 Sep 1998 14:34:31 +0100

All,

Working on a feature schema for Internet fax has raised some
questions/concerns about the 'base' set of media features, as represented
by the -media-features- draft.

Horizontal and vertical resolution
----------------------------------

Originally, there were separate x- and y- resolution features.  More
recently these have been reduced to just one ('dpi') on the basis that this
is the common case.  I vaguely recall a brief discussion that suggested
differential resolutions should be represented as a resolution ratio
parameter.  Having attempted to describe such a parameter for the fax
schema, the feedback I received was not entirely comfortable, and very
careful description is required if the feature is not to be open to
misinterpretation.

Here is my attempt to describe a differential-resolution feature:

>   dpi-xyratio = <rational>
>
>which is the ratio of dpi in x-axis to dpi in y-axis
>(such that dpi[x] = dpi[y]*dpi-xyratio).
>
>Therefore a resolution of 200*100 has a dpi-xyratio value of 2.
>
>If not specified, a value of 1 should be inferred.
>
>QUESTION: if dpi-xyratio is not unity, to which axis should dpi refer?

Personally, I prefer the separate x- and y- resolution values (e.g. dpi-x,
dpi-y).

#g

------------
Graham Klyne
([email-masked])