Archived posting to the Leica Users Group, 2015/07/14
[Author Prev] [Author Next] [Thread Prev] [Thread Next] [Author Index] [Topic Index] [Home] [Search]Lossless compression is not new or difficult, even Huffman did it in 1952 as a term paper project :-) On Tue, Jul 14, 2015 at 6:55 PM, Herbert Kanner <kanner at acm.org> wrote: > I was surprised to see in the manual that there was lossless compression > of the DNG. So I thought I'd try it out by taking two shots, one compressed > and one uncompressed. When I looked at my DNG file, I was astounded to find > a DNG of over 40 MB and a compressed one of about half that size. (I > deleted the negatives before thinking of writing this, so I can't give you > exact numbers. > > Well, I was at first astounded that lossless compression could be that > effective. Then I thought about the details of an image. Except where there > is really fine structure in the image, there will be areas where the data > does not change. A simple number triple, one giving a value for, say the > red pixel, the second giving a starting location in the file, and the the > third the number of consecutively stored pixels having the same value, > could easily result in a factor of two compression for lots of pictures. > And what I just described is a very unsophisticated compression method. If > anyone knows more about how this might have been done, I'd be very > interested. > > 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 for more information -- // richard <http://www.richardmanphoto.com> // http://facebook.com/richardmanphoto // https://instagram.com/richardmanphoto