LibTiff Mailing List
TIFF and LibTiff Mailing List Archive
November 2007
Previous Thread
Next Thread
Previous by Thread
Next by Thread
Previous by Date
Next by Date
Contact
The TIFF Mailing List Homepage
This list is run by Frank Warmerdam
Archive maintained by AWare Systems
Thread
2007.12.10 06:21 "Re: dpi settings", by Toby Thain
On 10-Dec-07, at 2:42 AM, Ron Croonenberg wrote: >> Sorry, perhaps I overstated it (the centimetre-gram-second system is >> deprecated), but there has certainly been some movement away from >> centi as a preferred prefix. > > Neah, I think it is still in fashion. > > btw, the seconds (minute etc) system isn't metric. metric is base 10, > time and degrees are base 60. That's from the old Greek era. The greek > thought there was something special with the numbers 3,4 and 5 > (remember > that triangle thingy ?) 3*4*5 happens to be 60 It may go back to the Greeks, but the reason why the Imperial system commonly uses highly factorisable numbers (12, 24, 60, ...) is clearly convenience of division into parts, when arithmetic is done mentally or manually. Other ancient systems also used bases such as 60. In these days of rocket science the virtues of the Metric system are more apparent (did Imperial or Metric man land on the moon? it would be interesting to know what Apollo engineers used). > >> I understand the metrication authority is largely disbanded, as their >> primary task is done. > > true, almost everyone uses it now. (except for the US and English > system > and some isolated tribe that was discovered a good while ago. They > use a > base 20 system.) It happens that no system in use is really 'pure'. > Look > at the way we count. It is considered base 10, however we still use > base 20 system 'remnants' for counting in language. When counting from > 10 till 20 we don't say '10 1' '10 2' '10 3'... however after 20 > we do. > That's language, not measurement... which has its own quirks. Not even all European languages are consistent in it. >>> For purposes of resolution, I doubt it. Do you find inches more >>> practical in this connection? >> >> Inches aren't used much, except in translating US based standards >> and documents. If you were to ask anyone aged 30 or less what >> an inch is, or how many inches in a foot, they probably couldn't >> give you a confident answer. > > to me it doesn't really matter what is used, as long as it is clear > what > system is used. I'm a 'hybrid', and am used to both Although 1.7 > inches > still sounds funny to me. (I just flip my ruler back and forth when > that > happens) > > > > ok, back to tiff ... does anyone know of a simple routine to read a > tiff file so that I can stick the pixel colors in a 2D matrix ? Ah, a good old FAQ. --Toby > > thanks, > > Ron > > _______________________________________________ > Tiff mailing list: Tiff@lists.maptools.org > http://lists.maptools.org/mailman/listinfo/tiff > http://www.remotesensing.org/libtiff/