Archived posting to the Leica Users Group, 2011/12/30
[Author Prev] [Author Next] [Thread Prev] [Thread Next] [Author Index] [Topic Index] [Home] [Search]Herb raised a good point, if the compression is simply as stated, then it's not a variable length compression, but simply a 12 bits (in a 16 bit word) to 8 bit/byte conversion. The fact that it's variable size means that they have some other minor compression going on. On Fri, Dec 30, 2011 at 1:18 PM, Tina Manley <images at comporium.net> wrote: > That's true of other kinds of compression like the LZW. Photos with lots > of color and detail do not compress as much as simpler photos. > > Tina > > On Fri, Dec 30, 2011 at 4:10 PM, Jim Nichols <jhnichols at lighttube.net > >wrote: > > > Herb, I can only offer an opinion. I suspect that the compression is > > somewhat dependent on the content of the image, resulting in the > variation > > that you find in the size of the compressed files. > > > > Jim Nichols > > Tullahoma, TN USA > > ----- Original Message ----- From: "Herbert Kanner" <kanner at acm.org> > > To: "Leica Users Group" <lug at leica-users.org> > > Sent: Friday, December 30, 2011 3:00 PM > > Subject: [Leica] DNG compression > > > > > > > > I'm probably flogging a dead horse, but there is one unanswered > question. > >> In view of the slgorithm that showed up in a forum: multiply the value > that > >> is between zero and 4096 by 16 and take the square root, thus mapping > the > >> 12-bit number into an 8-bit one, i.e. 0 to 256, how come uncondensed > DNGs > >> are all exactly 36.4 Mb, but the condensed ones have varying sizes? > >> > >> > >> -- > >> Herbert Kanner > >> kanner at acm.org > >> 650-326-8204 > >> > >> Question authority and the authorities will question you. > >> > >> ______________________________**_________________ > >> Leica Users Group. > >> See http://leica-users.org/**mailman/listinfo/lug< > http://leica-users.org/mailman/listinfo/lug>for more information > >> > >> > >> > > > > > > ______________________________**_________________ > > Leica Users Group. > > See http://leica-users.org/**mailman/listinfo/lug< > http://leica-users.org/mailman/listinfo/lug>for more information > > > > > > > -- > Tina Manley, ASMP > www.tinamanley.com > > _______________________________________________ > Leica Users Group. > See http://leica-users.org/mailman/listinfo/lug for more information > -- // richard <http://www.richardmanphoto.com>