Re: [hylafax-users] 408 Horizontal Resolution

[Lee Howard <faxguy@xxxxxxxxxxxxxxxx>]

On 2004.03.15 17:19 Kris Henderson wrote:
> Hi,
>
> I'm trying to get Hylafax CVS HEAD to send a fax that has a resolution
> of 408x392.  The resolution of my image is 408x392 and is 3456 pixels
> wide by 4227 pixels tall.
>
> I am calling sendfax on the command line like this:
> 	/usr/sbin/sendfax -n -G -d 1234567 file.tif
>
> In /var/log/messages, I am seeing:
> CONVERT DOCUMENT: bin/tiff2fax -o docq/doc37.tif;32 -r 391 -w 1728 -l
> 280 -m 4294967295 -1 docq/doc37.tif.37
>
> I have a few questions:
> 1.  Why is the vertical resolution set to 391?  I thought it was
> supposed to be 392

R8 resolutions are defined by T.30 as 7.7 lines/mm vertically, and R16 
is 15.4 lines/mm.  Since there are 25.4 mm/inch those vertical 
resolutions calculate out to be 195.58 lines/in and 391.16 lines/in 
respectively.  Rounding rules say you round up with the former and down 
with the latter.

> 2.  Shouldn't the width be 3456 or is it ok that -w is 1728 and
> tiff2fax
> won't change the
> Horizontal resolution, 1728/204 and 3456/408 being equal width?

To avoid pixel-width conflicts between resolutions the conversion 
utilities always specify page width in R8 resolution measurements - 
even if R8 resolution is not being used.  Basically when it says "-w 
1728" it means 215 mm; it's specifying a width measurement and not a 
pixel count.

See this thread:
http://www.hylafax.org/archive/2000-10/msg00114.html

> 3.  Anything special I need to do to enable 408x392 faxes?

I don't understand.  You mean 408x392 versus 408x391?

Lee.

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