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Re: [Sheflug] PDF Tools
Hi Simon,
Thank you for the DjVu v3 spec. I had not seen that before and the worked
examples are very useful. Effectively. it makes a guess at a background
colour then only has to encode the foreground. Not satisfied, it tries
other backgrounds and compares output sizes. It then reduces its page size
and tries again and will iterate until it is not making a size saving.
The patent coverage is a little worrying although after digging djvubind ->
djvuLibre the page ( https://djvu.sourceforge.net/ ) mentions that
LizardTech release the reference implementation of DjVu under the GNU GPL
in October 2000.
Regards
John
On Tue, 7 Feb 2023 at 10:24, Simon Ward <simon@xxxxxxxxxxx> wrote:
> On Sat, Feb 04, 2023 at 01:22:57AM +0000, John Southern wrote:
> >DjVu has superior compression, but I think it is proprietary.
>
> The DjVu spec is open, although I can’t find it on djvu.org there’s a
> copy on archive.org[1] (they used to support the format for uploads).
> According to Wikipedia there are, however, patents covering it[2].
>
> [1]: https://archive.org/details/DjVu3Spec
> [2]: https://en.wikipedia.org/wiki/DjVu#Format_licensing
>
> Simon
>
> --
> A complex system that works is invariably found to have evolved from a
> simple system that works.—John Gall
>
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