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diff --git a/usergrps/uktug/baskervi/4_5/clark1.tex b/usergrps/uktug/baskervi/4_5/clark1.tex new file mode 100644 index 0000000000..6dc4809a50 --- /dev/null +++ b/usergrps/uktug/baskervi/4_5/clark1.tex @@ -0,0 +1,298 @@ +\providecommand{\ie}{\emph{i.e.}} +\providecommand{\ctan}{\textsc{Ctan}} +\providecommand{\cd}{\textsc{CD-rom}} +\providecommand{\unix}{\textsc{Unix}} +\providecommand{\dos}{\textsc{Dos}} +\providecommand{\ie}{\emph{i.e.{}}} +\let\textss\textsf +\title{Malcolm's Gleanings} +\author[Malcolm Clark]{Malcolm Clark\\ +Computing Services, University of Warwick\\ +Coventry, CV4 7AL\\\texttt{m.clark@warwick.ac.uk}} + +\begin{Article} +\section{True colours?} +The boost given to the use of colour in \LaTeXe\ is not an unmixed +blessing. There are pitfalls and problems lurking round these new +corners. There is always a huge discrepancy between the colours we +can produce on a monitor screen and the hard copy version that a +printer will produce. It can be very frustrating to spend time and +effort getting the colour balances `just right', and then finding that +the hard copy looks nothing like the original. Especially when you +have to pay for the hard copy. Why are there discrepancies? The +mismatch is in the very nature of the processes involved -- it is not +because something has gone wrong. + +Let's start at the beginning, and assume that we are concerned with +the transition from colour on the screen to colour on the page. +Perhaps the first thing we should realise is that no two people see +colour in quite the same way. Intra-species perception is well-known +to be different, but even between individuals (ignoring those with +some physiological perceptual malfunction, like colour blindness), +response to different colours is different -- \ie\ what different +people call `blue' differs -- well, most people agree about blue, but +how many agree about `mauve' or `puce'? Any perceived colour may be +understood as the sum of three primary colours. This gives us a first +clue, since it means that we can represent a colour as the sum of +three stimuli (a tristimulus), and we can think in terms of +characterising any colour by locating a unique point defined by three +(orthogonal) axes. In fact no monitors can represent the full range +(or \emph{gamut}) of colours. Their actual performance falls short. +Even before we start, we cannot hope to represent all possibilities. + +The colours we view on a monitor are emitted colours -- they are +generated by the three electron guns of the device (there are other +technologies, but the principle remains much the same). The advantage +here is that each model of monitor can be calibrated, and in fact the +range of possible colours can be determined. From time to time the +colours may drift, and it is possible that adjacent `identical' +machines may appear to have different colour outputs. If you always +work on the same machine, you can guard against this. Recalibrating +every machine is rather time consuming. Another advantage of using the +same machine every time is that the background and lighting is +unlikely to change to much. + +By virtue of our evolution, our eyes are well adapted to slow changes +in light level, and also to slow, but moderate changes in the major +illuminant (as daylight varies through the day, for example). Changing +the incident lighting does not change the emitted light on the +monitor, but since the frame of the monitor and everything else in the +room is changed by changing the illumination, you can end up thinking +that it looks different. The illumination in many rooms is a bit +arbitrary: it may be fluorescent tubes, which have a rather limited +spectrum, or it may be normal incandescent lights, which have a +different spectrum, and occasionally it is north light (also known as +\emph{daylight}) illumination. + +This last is an interesting diversion. This is the lighting condition +under which most, if not all, standardised colour determinations are +performed. Anyone who is working seriously with colour will use north +light (most artist's studios, for example, will be oriented to be lit +naturally in this way). In fact, this is one of the reasons why the +hard copy will appear incorrect: the lighting conditions are likely to +have changed. And anyway, the hard copy will look different under +different illumination. The hard copy is made visible by reflected +light. What is reflected is dependent on the light source. The +distortions of sodium street lights are well known, but the same sort +of effect is true of fluorescent or incandescent lights. The north +light works reasonably well as a standard because of our environmental +background, and because it is based on the light source which was +available as our eyes evolved. + +There is at least one more factor to be considered: the printer. Just +as a monitor can only produce a proportion of the possibilities, so +too the printer is restricted in its range of possible colours. In +fact it is worse: while the monitor can use the linear additivity of +the primaries, the printer's primaries are anything but linear, and +the mixing is subtractive. Adding the primaries on a monitor gives +white: on the printer it will give a theoretical black (more of a +muddy purplish darkness). It is therefore rather difficult to +transform from the co-ordinates representing the colour on screen to +some faithful (whatever that means) rendering on the page. There are +lots of dodges which can be adopted. The most comprehensive is to +employ some sort of lookup table. This depends on the measurement of +many samples -- it is a lot of rather tedious work, spread over lots +of subjects (remember the underlying psycho physical variation). + +Briefly then: +\begin{enumerate} +\item the colours you see on the monitor are a subset of possible + colours; +\item the illumination of the room can be important +\item the printer does not have the capability of rendering all the + colours visible on the monitor; +\item you will probably view the hard copy under a variety of lighting + conditions. +\end{enumerate} + +Is there any hope? Some printers are better than others. The machine +we use here at Warwick, a Tektronix Phaser, is essentially a wax +crayon machine; it is reasonably good, for the price. The best hard +copy devices are dye sublimation printers and they are very expensive. +If you stick to primary colours, and colour gradation is not a key +issue, the Phaser is excellent. With a lot of time and effort you +might achieve finer quality work with it. If you are looking for a +photographic quality reproduction you would have to use other +technologies -- and even then, you can fail. In many cases though, +hard copy is irrelevant. The display medium is genuinely the monitor +screen. If we think in this way, we realise that many other +possibilities are introduced, like running video clips, or even pieces +of software, within a document or presentation (yes, \LaTeXe\ does not +yet support such extensions explicitly, but a suitable +\texttt{\char'134special} could). We usually have the feeling that +paper is the objective, but it does not have to be. Sometimes it is +more convenient, but at other times it is restrictive. + +Any of the good ideas for this came from presentations by Chris Lilley +of the Computer Graphics Unit at Manchester Computer Centre; the +mistakes are mine. + +\section{Trivial pursuit} +For many years I have been toying with the notion of creating a +special \TeX\ edition of \emph{Trivial Pursuit}. There are those who +contend that \TeX\ \emph{is} a trivial pursuit, but I will have +nothing to do with this view. To assist in the creation of this game, +and to tempt the likes of Waddington's, I will start to include +examples of the questions in this column. The first question is in two +parts. The first part is borrowed from the ACM 1994 Computer Bowl +quiz: ``Only one person in all of computing's history has ever won +both the ACM Turing Award for lasting technical achievement and the +Grace Murray Hoppper Award for work done prior to reaching the age of +thirty. Who is that person?'' + +The second part is this: ``The Computer Bowl quiz was created and +produced by the Computer Museum, Boston. What link does this have to +the answer for the previous question?'' + +\section{Dutch bearing gifts} +I quickly snapped up my NTS \cd{} when it was offered through the +group. I was motivated by a curious mixture of support for the +efforts of another group, and a willingness to get tangled up in a +flashily trendy technology, although +I have to admit that I'm not yet convinced by \cd{} technology. +%But I have to admit that I'm not yet +%convinced by \cd{}. It seems to me like a suspect technology which is +%only half way there, or one which has been rather over-hyped. While +%the shiny disks can contain a fair amount of data -- 640 Mbytes -- +%this seems to me to be pretty inadequate for multimedia applications +%which include still or moving pictures, and the access times for +%random movements around the disk are appalling (almost as bad as World +%Wide Web connections around the InterNet). It is fine for sequential +%text when it is read in a linear fashion. In other words, pretty +%boring stuff. However, as an archiving mechanism it offers some +%potential, ignoring the extreme difficulty with which additional +%material can be added. + +One advantage of the NTS \cd{} is the booklet +which comes with +it. Once you have installed the suite, and basically it wants to run +from the \cd{} drive, you find that it is enormously configurable. +Because of the many varieties of printers, screens and editors which +are available in \dos{} systems, you could have many happy hours ahead +of you getting things right. I get the feeling that it is assumed that +you will like fiddling. There is no doubt that great effort went into +this, and equally, that you can eventually install all the relevant +bits and pieces. I wonder how you would manage to install something +useful if you didn't want to use the 4\dos{} shell which is the +default. Clearly the developers thought this an unlikely decision. +They say ``One might object that using 4\dos{} batch files deprives +the old-fashioned \texttt{command.com} users from the benefits of +4\TeX. We happen to think that this would only be a mild punishment +for not recognizing how good 4\dos{} really is.'' Well, pardon me! +Oddly, they fail to mention that continued use of 4\dos{} involves +payment of a shareware fee. + +Once you do get it installed, you still appear to have great power to +customise the options the shell offers. However, I am still unclear +how to change the drivers (you are provided with a variety of screen +drivers and I really wanted the one which occupied least memory; this +is not the default). I was also surprised that among the huge range of +choices of formats you are offered, the simple \LaTeXe\ or plain \TeX\ +is not among them. It is rather like going into Macdonald's and trying +to get a burger without the limp lettuce or the ketchup. In this case +of the formats, the lettuce and ketchup is Babel. + +On the whole, I suspect the shell is about as good as you can get with +\dos{}. It appears workmanlike. I'm afraid it does look dated though. +Windows is here. The true \textsc{blu}e \TeX ie may resent it, and see +it as a step towards perdition, but for many of us Windows is the +least unacceptable face of the Intel chip's range of operating +systems. + +But compared to PrimeTime's \cd{}, this is a joy. At least the NTG's +offering has the advantage that you can browse it a bit like you +browse \ctan. If there is a useful file there, you can find it and +pull it out. The PrimeTime \cd{} is tarred and feathered (or zipped) +so that you can't actually find anything unless you know where it is. +It contains almost all the contents of \ctan, but nowhere does it +actually give you the date of this snapshot. The sheer mass is +daunting. And layered on the top of this is an assumption that \unix{} +is the way the truth and the life. It makes a point about distributing +source code: ``Binary-only distribution prevents recipients from +modifying or learning from the internals of software.'' I have to +confess that I'm not terribly interested in computer programs. I'm +much more interested with what I can do with the program. The days of +immersing yourself in the exciting details of source code should +surely be passing. The terms `nerd' and `propellor-head' or +`techno-weenie' spring to mind, almost unbidden. People you would +prefer to avoid at parties. Like the ones who want to tell you the +latest exciting details of \LaTeXe\ or \textss{dvips}. If I have to +examine the internals to work out why \TeX\ inserts a skip at some +particular point I'll drift silently to Quark Xpress.\footnote{In + passing, if I had put a fraction of the effort into Quark that I + have in \TeX\ and \LaTeX, I would be emminently employable at any + number of publishers. On the other hand, I would probably also have + a pony tail and an earring.} + +What is the basis for my rant? First, virtually all the discussion in +the handbook is in terms of \unix{}. This is partly fair, since +PrimeTime admit that their experience is almost wholly with \unix{}, +and does not really spread to other platforms. Until you actually look +at the \cd{} itself (and yes, it is readable under \dos{}, Windows and +the Mac), you don't realise that it might just be useful to you. There +are the tools needed to unzip the many files on platforms other than +\unix{}. I was mildly amused that the Windows unzip application came +as a \texttt{.z} file itself (\ie\ \emph{zipped}), but since there is +also a \dos{} executable, that is hardly insuperable. The Mac version +of \textsf{unzip} came in two versions -- one a BinHex file, and the +other a self extracting archive. The latter is the one that most of us +would prefer. Those of us who enjoy the Mac tend to enjoy it because +we don't have to mess around. We can get straight on with the real +jobs. In order to use this archive you woud have had to dust down your +copy of ResEdit and mess around changing file types: this is close to +binary editing. It is not the sort of thing you do every day. So I +BinHexed it, and there was the archive, which worked wonderfully. +Except. There is always an except. Turning it loose on a part of the +\cd, on a genuine \textsf{zip} file, it just wouldn't work until I +realised that you had to copy the \textsf{zip} file to your hard disk +and then unpack it. Otherwise you get unintelligible errors. This is +clearly a failing of this particular implementation of \textsf{unzip}, +but it would have been `friendly' if the manual had pointed it out. +After all, someone must have tested it all out, mustn't they? This +means you have to waste disc space on the \textsf{zip}ped and unzipped +files together. + +This aside, my main complaint is that to find anything you must first +unzip the file you think it might be in. Since the unzipped files +would amount to two gigabytes or so, you cannot really just unzip the +whole archive and browse. Maybe I'm being uncharitable. After all, if +you want a particular driver, you look for that driver, and not +another one. Unzip it and off you go. No-one really wants to browse +through all the bits of particular drivers, do they? But think, +there's all that source to modify and learn from. I can hardly wait. +%Does it have \LaTeXe? you ask. Clearly you haven't been paying +%attention. It is the contents of \ctan. Therefore \LaTeXe\ is there, +%and just where you would expect it. It is also the `current' version, +%rather than the pre-release which the chronologically earlier NTG +%\cd{} contained. + +The text of the handbook is +largely taken up with technical details, but has a foreword +George Greenwade, the \emph{emminence grise} of \ctan, a +note on TUG by Sebastian `\emph{Il Presidente}' Rahtz (in +uncharacteristically mellow and benevolent mode), and one of Kees van +der Laan's idiosyncratic expositions entitled `What is \TeX\dots'. +There is no doubt of Kees' enthusiasm. He writes at a frenetic pace +which often leaves the tedious details of conventional sentence +structure far behind. You will either find it exhilarating or +debilitating. At times he seems capable of raising himself several +feet off the ground purely by belief and pace alone. The ground looms +up very large and unfriendly towards the end. + +I'm a little bemused by it all. In both cases, opportunities seem to +have been missed. Or perhaps worse, \TeX\ is again cast in the light +of the avid techno-whizz. Both of these offerings are just barely +useful, and save themselves from consignment to one of the outer +Hells. What is it that we should be doing? The contents of \ctan\ are +undoubtedly convenient, but the compression of the PrimeTime disc does +erect a barrier which is too high. Better to trim it mercilessly but +make it more accessible (yes, I know there is a problem with depth of +directories: \ctan\ goes deeper than the \cd\ format will allow). The +NTG \cd, thanks to the shareware component, is just waiting to turn +sour. The scrupulously honest will have difficulty creating an +alternative integrated \TeX\ system. And anyway, it still isn't +Windows! Time to get into the 90s, before the century ends. But at +least it is possible to find useful files before you find them disc +space. + +\end{Article} |