% notes on 1st meeting of UK TeX Users' Group
% held on 15 March 1989 at London School of Economics
% 
% hastily put togther under conditions of pressure and duress by
% David Osborne, Cripps Computing Centre, University of Nottingham
% email: d.osborne@uk.ac.nott.clan
%
% ==use plain format==
%

\def\Item{\item{$\bullet$}}
\def\Itemitem{\itemitem{\ --\ }}
\def\\{$\backslash$\relax}
\def\specials{{\tt \b special}s}
% define the LaTeX logo in two parts (we want the La separately)
\def\La{{\rm L\kern-.36em\raise.3ex\hbox{\sc a}}}

% now some other useful odds and ends


\article{\bf Notes on 1st meeting, UK \TeX\ Users
Group} 
The London School of Economics was the venue on 15th March for the
first meeting of a UK \TeX\ Users' group (numbering November's
inaugural Nottingham meeting as the `zeroth'.
Unlike the earlier meeting, the LSE meeting took a theme for all the
talks: `Graphics and \TeX'.  Because more time had been available to
plan and publicise the event, it was good to see a broader
representation of \TeX\ users instead of the bias towards those from
academe and a rough head-count gave between 40 and 50 attendees.

\section{`Business meeting' ({\it Malcolm Clark\/})}
As the gathering was intended to be the first official meeting of a
national UK user group, Malcolm Clark began with what he called a
`business meeting' to discuss matters relating to the organisation
of a user group, such as a constitution and the formation of an
organising committee.  Malcolm had prepared a draft constitution for
the group, copies of which he distributed.  This covered not just
administrative matters, such as arrangements for annual meetings and
the number of members at these to form a quorum, but also raised some
questions which he asked those present to consider and decide at the
next meeting.  These covered important issues such as the relationship
of a UK group to other European \TeX\ user groups and to TUG itself,
together with the financial (and political) implications of membership
fees.  Clearly, these will require a good deal of discussion to sort
out but Malcolm argued for co-operation with other groups, where
possible.  Communication of information between users in the group and
between this and other groups is obviously an important point and some
suggestions were made regarding a newsletter.  Malcolm offered to make
the \TeXline\ mailing list available, though \TeXline\ will continue
as an independent publication.  An {\it ad hoc} election of a
committee to organise the group's future activities was then
conducted.

Finally, to lead in to the theme of the day's meeting, \TeX ed copies
of a recent article by David Rogers were distributed; this had first
appeared in the \TeXhax\ digest, 89(8), 
 later printed in \TUGboat\ as
`Computer Graphics and \TeX\ -- A Challenge'.

\section{Picture Languages ({\it Sebastian Rahtz\/})}
Sebastian had, at last, a chance to give this talk, which had to be
postponed from the Nottingham meeting for lack of time.  It was worth
waiting for and he described the many approaches which can be taken to
include graphics in \LaTeX\ documents.  The hardware he used at
Southampton for this was a Sun 3/50 workstation with some unspecified
(large) number of megabytes of memory.

He began by surveying the field to assess the range of
pictures/graphics which someone might want to include in their
(\La)\TeX\ documents.
\Item colour photographs  --   not yet possible;
\Item halftones;
\Item line (`art') graphics  --  hand drawn;
\Item computer generated, bitmaps  --  `black boxes';
\Item structured computer graphics  --  object-oriented;
\Item algorithmic graphics  --  generated from data;
\Item bitmaps  --  e.g., digitally transformed images;
\Item character graphics
          \Itemitem simple {\sc ascii} characters
          \Itemitem Costabel's sprite macros (as described in \TeXhax
                88 \#106)
           which take a bitmap diagram and generate a character;
\Item dots  --  \PiCTeX's way of generating graphics: hungry of time and memory;
\Item Renner's category structure diagrams  -- 
          these use \LaTeX's picture commands and fragments of lines and arcs;
\Item {\tt epic} and {\tt eepic}  -- 
      as above, but supplemented using \specials;
      {\tt eepic} is the extended version
          \Itemitem these require a \dvi\ driver which understands
                    {\tt tpic} \specials
          \Itemitem {\tt tpic} is the front-end software
\Item \MF  --   single \MF\ characters  representing diagrams -- 
    again, a black box
\Item \TeX\ halftones  --  e.g., Knuth's \TUGboat\ (8,2) paper
\Item graphics using \specials\  -- 
    no standardisations yet; this introduces the problem
    of \PS\ versus non-\PS\ printers and what is acceptable as a lowest
common denominator
\Item graphics produced by post-processing the \dvi\ file  -- 
    \specials\ in the \dvi\ are
    treated by a \dvi\ transformer which writes a new \dvi\ file;
    e.g. John Renner's \TeX tyl,
    but this introduces problems in reliability and restrictions on text
    inclusion.
\smallskip\noindent
He suggested that it would be useful to agree that standard
graphical objects, (e.g.~a circle), are available -- not everyone
wants to use a picture language to obtain these.  He then discussed
some examples of `interactive graphics' ({\it MacDraw\/}; \PS\ `in the raw';
and more sophisticated tools such as {\it Adobe Illustrator\/}) before
considering Fig, a {\it MacDraw\/}-like package on Sun workstations
(also available as {\tt xfig} to users of the X-Window system).

Fig generates a description of objects in the drawing in its own
graphics language.  This is translatable into \PS\ (richer than Fig,
so presenting no translation problems); {\tt tpic} code (with some
loss of Fig facilities); and into \LaTeX\ picture primitives.
Sebastian showed some examples of output from each of these methods on
a sample graphic and demonstrated that some produced good
approximations to the desired results, while others diverged a long
way from them.

He drew the following conclusions:
\Item graphics primitive objects (lines, rectangles, circles) can be
    filtered through drawing programs and included in (\La)\TeX\ documents
    with varying success;
\Item the best results are naturally obtained when there are no constraints
    (from hardware, for example;
     graphics standardisation is doomed when we have to conform to the lowest
     common denominators;
\Item \TeX's graphic primitives require picture drawing in ways that
     people don't find convenient.

\section{\PS\  ({\it David Marx\/})}
Dave Marx of Imperial College described the basic features and
capabilities of the \PS\ page description language.  He noted that for
typesetting applications, it is not intended to be used directly and
is consequently not as powerful in this area nor expressed at as high
a level as \TeX.  His talk was a useful reminder of \PS's
capabilities, since most of the other speakers during the day
introduced the topic of
\TeX's relationship with \PS, or methods for introducing graphics described in
the \PS\  language into their documents.

\section{\PS\  in \TeX\ ({\it David Brightly})}%
Following the \PS\ theme, David discussed \psfig\ as a means of
incorporating \PS\  graphics into a (\La)\TeX\ document
(see David's article on this subject in
           \TeXline\ 7, Feb 1988.
\psfig\ was written by Trevor Darrell and described by him in
`Incorporating \PS\ and Macintosh figures in \TeX', part of the \psfig\
documentation and
          available from good archives everywhere.

David began by stating what \psfig\ is not: it is not a drawing
program like {\it fig} or {\it MacDraw\/}; not a picture language like
{\it pic\/}; not a \TeX\ macro package like \PiC\ or the \LaTeX\
picture environment; nor is it a \dvi\ post-processor like \TeX tyl.
He described it as `electronic cut and paste for \PS\ graphics'.
\psfig\ is available as a \LaTeX\ style option or a \TeX\ macro package
and allows the user to scale, translate and clip an image described in
\PS.  The \psfig\ code consists of about 300 lines of \TeX\ and
requires a \dvi\ driver which supports two simple, though
\psfig-specific, \specials.  These allow `inline' \PS\ and the
insertion of a file of \PS\ code and can be easily modified in the
\psfig\ code to work with specific
\dvi\ drivers which support \specials\ of this form.
David said he had successfully used \psfig\ with {\tt
dvi2ps} (which one?) and with Arbortext's {\sc dvilaser/ps}.

The \psfig\ macros propagate information from pre-existing \PS\ files
into the \dvi\ file by means of \specials, though the \PS\ files are
required to  include the
|%%BoundingBox| comment.  This gives the co-ordinates of the bottom
left and top right corners of a rectangle enclosing the graphic
described by the \PS\ code and is used by \psfig\ to scale the graphic
to fit the space chosen by the document author.  This space need not
correspond to the aspect ratio of the graphic, since
\psfig\ is capable of unequal scaling in $x$ and $y$.
In fact, by making the `box' into which the graphic will be included
of zero size, it is possible to overlay the \PS\ with normally
\TeX-typeset material.

David outlined the advantages of the \psfig\ approach: it is not
limited to specific types of graphic, e.g., line graphs; graphics from
any package which can generate \PS\ can be included; and it is simple
to use, so there is not much to go wrong.  There are disadvantages:
output can only be to \PS\ devices -- in the light of the \TeX-and-\PS\
coverage during the meeting, plus some comments that no-one venturing
into `serious' typesetting would consider a non-\PS\ printer these
days, this doesn't seem much of a restriction; and there would be
typeface mismatch between annotations in the graphic and the body text
of the document (assuming use of CM fonts in the body text).

\section{Chemical diagrams ({\it Tony Norris\/})}
The typesetting of chemical disgrams integrated with scientific text
was described by Tony Norris, of the Polytechnic of the South Bank,
London.  The advantages of being able to accomplish this task were
obvious, with `traditional' methods costing in the region of \quid40
per page and being very time-consuming.  However, the nature of the
diagrams introduced particular problems: they have a precise,
predefined geometry; must have consistent ring-sizes between diagrams
and it must be possible to tesselate different rings; correct
relationships of atoms and bonds must be preserved; and the annotation
of the diagrams, which makes heavy use of subscripting, should ideally
be unified with the body text.  One approach which had been tried and
rejected was to store each ring or bond as a \MF\ character; however,
this was not feasible as the diagrams might require a bond at any
angle and do not allow `quantised' angles.

Tony described the DrawChem program, an interactive graphical editor
which had been designed for this application.  It allows structured
editing of a diagram, permitting duplication and modification of
structures (i.e., rings), and results can be exported to PageMaker or
Ventura (maybe
\TeX, too).

\section{Typesetting pictures in \TeX\ ({\it Adrian Clark\/})}
Adrian discussed the techniques for using \TeX\ to typeset pictures
which could be included in a \TeX\ document.  The ability to do this
brings advantages of economising on cost, improved quality of results,
shortened turn-around time compared with traditional methods, and user
convenience.  He pointed out that traditional methods of including
computer graphics as illustrations in documents introduce distortions
from photographing display screens and that there is the added cost
and time due to film processing.  Adrian went on to describe
commercial uses of halftoning.  A magazine illustration, for example,
would use a resolution of approximately 150\,dpi.  Resolution of
book illustrations is usually expressed in terms of the screen
frequency used; monochrome illustrations using a screen of 600
lines/inch, and colour using 1800 lines/inch.

Methods for halftoning in \TeX\ were then covered.  These include
\Item \specials\ and bitmaps  -- 
    these are device-specific, though efficient for
    processing with \TeX; however, the size of the picture
    must be known and specified in advance;
\Item using \MF\  --  the picture can be set as a single, large glyph;
    this can cause problems on some printers and you might run into
    problems with your \dvi\ driver;
\Item halftone fonts  --  as described by Don Knuth in his TUGboat article;
    care is needed with calibration of the typesetter to obtain the best
    results.  Adrian showed some very successful examples of images
    he had typeset using this last method.
\smallskip\noindent
Summing up, Adrian looked to future developments in this area.  He
confirmed that, as might be expected, typesetter output gives
publication-quality results.  For non-typesetter output, higher
resolution devices (e.g., 1200\,dpi laser printers) will make a big
difference to the results which can be achieved, although current
laser output is probably adequate for internal reports.


Following a question and answer session, the meeting closed with
thanks being expressed to Carol Hewlett of LSE who, with Malcolm
Clark, had arranged the meeting.  The date of the next meeting wasn't
announced, but has subsequently appeared in the bytes of {\sc uk\TeX}.
It will take place on Wednesday, October 11th at Aston University,
Birmingham, the theme being `Fonts -- Design and Use'.  
\author{David Osborne}
