Re: [hylafax-users] 2D encoding

[Lee Howard <faxguy@xxxxxxxxxxxxxxxx>]

On 2003.10.19 08:15 Steve Underwood wrote:
> Hi all,
>
> Looking at the source code for HylaFAX it seems that 2D encoding 
> isn't really supported.

It depends on what you mean.  HylaFAX uses Ghostscript and libtiff to 
prepare documents for outbound transmission, and both adequately encode 
2-D lines for use in both MR (partial 2-D) and MMR (full 2-D) images.  
HylaFAX can send such images just fine.  However, HylaFAX's own TIFF 
encoder which is primarily used to image the tagline onto the outbound 
images only does 1-D encoding.  That's why no taglines are imaged on 
MMR documents yet... the encoder needs some enhancement... but this 
shouldn't cause anyone to say that HylaFAX doesn't support 2-D MR or 
2-D MMR, because it does.

> Although 2D is an option, it seems to be a fake, using 1D coding in 
> reality.

I assume you refer to the tagline imaging function that I mentioned 
already.

> Since libtiff appears to do 2D coding properly, the 2D infrastructure 
> seems to exist.

libtiff doesn't provide any memory-only encoder/decoder functions as 
far as I'm aware.  So we can decode it from a filesystem or encode it 
to a filesystem, but we cannot do those from or to memory, thus HylaFAX 
must have its own encoder and decoder for memory functions.  The 
decoder came from the same source as libtiff's (Frank Cringle's 
viewfax), so it was easy to keep updated by comparing with libtiff 
sources.  The encoder seems to be unique to HylaFAX... at least it 
didn't seem to compare well to libtiff's encoder when I last looked.

> Is it something that has just not been finished, or is there some 
> solid reason for not doing full 2D encoding.

The encoder for tagline imaging could most certainly use some 
enhancement, and contributions are welcom ;-)

Lee.

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