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2007.12.10 01:43 "Re: dpi settings", by Toby Thain
On 9-Dec-07, at 11:01 PM, Graeme Gill wrote: > Bob Friesenhahn wrote: >> Here in the US, the ruler that I have available is marked with >> inches and centimeters. Are you saying that rulers in the rest of >> the world are no longer marked with centimeters? If they are not >> marked with centimeters, then what are they marked with? A ruler >> marked with millimeters or meters would not be so convenient. > > I'm saying that for some time, cm is a deprecated unit, > and mm is the preferred unit. How is it even possible to deprecate a Metric unit? It's only a prefix, and the prefix exists in order to control magnitudes. What evidence is there that centimetres are being "phased out"? The metrication committee in Australia produced a truly excellent document nearly 30 years ago which covered "preferred" and "non- preferred" units... I don't recall if suffixes were treated in the same way, but I think so. Do Australian standardisation authorities still retain the ability to produce clear guidelines? If so, perhaps you can cite them. But I don't see how this is going to affect TIFF one way or the other. > Yes, many rulers > sold here are marked only in mm (although, naturally the > markings are at 10mm intervals :-) In some senses this is > a subtle distinction, but it's still an irritation to > be converting to/from cm, and adds possibly confusion > and room for misunderstanding. For purposes of resolution, I doubt it. Do you find inches more practical in this connection? > >> It seems natural that centimeters was used since it is easiest to >> measure the width and height of a computer screen or page-sized >> object (e.g. sheet of paper) in centimeters rather than in meters >> or millimeters. > > I know what you mean and had a similar reaction myself initially, > but it > turns out in practice that mm is pretty convenient, especially for > paper > size, which is where I trip over the cm/mm thing all the time with > desktop > applications. I never found that when I was working in pre-press in Australia. It was dpi all the way. > It's a whole number with adequate precision for very many > everyday tasks (woodworking is another one that springs to my > mind). For > grosser scales, a one digit decimal on the meter is often the way > to go > (ie. 3.1 meters). It's true though that in advertisements, cm is > used for > TV display sizes. I guess for screen rulings and pixel density > pixels/mm > isn't so great, although it is something I've standardized on > internal in > my software (reduces my confusion). > > In much official usage (ie. rainfall - when there is any!), mm are > what's > used. We're wildly off topic now. > It's hardly uniform amongst the population - when the metric system > was introduced here we were taught cm, since they where closer in size > to inches, but since then there has been an attempt to standardize on > prefixes that are a multiple of 1000, that's been partially > successful. > > I think that Andrey's observation about technical and non-technical > use probably reflects the situation here in Australia It's not just technical versus non-technical; it's also subject matter. For instance, why do you not question the ubiquity of Imperial INCHES in the pre-press/publishing context (TIFF's home turf)? In a metricated country, isn't that infinitely more confusing than using a metric prefix for a metric unit? > as well to a fair > degree, and it will come down to what's currently being taught in > schools as to what future trends in popular usage are. One should only hope the trend of Americanisation there does not lead to abandonment of Metric in toto. --Toby > > Graeme Gill. > > _______________________________________________ > Tiff mailing list: Tiff@lists.maptools.org > http://lists.maptools.org/mailman/listinfo/tiff > http://www.remotesensing.org/libtiff/