[Leica] Yet another surprising fact about the M (240)

[Richard Man]

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.
>
>
>
>
>
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