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April 2012

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2012.04.11 09:48 "tiff2pdf fit image to page - how does it scale?", by David E Meier
2012.04.11 10:25 "Re: tiff2pdf fit image to page - how does it scale?", by <pullmoll@t-online.de>
2012.04.11 12:20 "Re: tiff2pdf fit image to page - how does it scale?", by David E Meier
2012.04.11 14:49 "Re: tiff2pdf fit image to page - how does it scale?", by Lee Howard
2012.04.11 22:38 "Re: tiff2pdf fit image to page - how does it scale?", by James Cloos
2012.04.12 01:49 "Re: tiff2pdf fit image to page - how does it scale?", by Steve Underwood

2012.04.12 01:49 "Re: tiff2pdf fit image to page - how does it scale?", by Steve Underwood

On 04/12/2012 06:38 AM, James Cloos wrote:
> Some fax software -- and perhaps some fax hardware -- prepends the
> header to each page rather than overlaying the header on top of the
> first so many mm of each page.
>
> I suspect your tiff has been through such an xform.
>
> All a4, letter and legal faxes should be 1728 pixels wide, which is
> approx 104 dpi wide.
>
> A4 paper is 595.27559 x 841.88976 (ps/pdf) points.  IIRC, low and high
> res faxes are 98 and 196 dpi tall.  841.88976 * 196 / 72 = 2291.81,
> which suggests that your fax is about 30 pixels (11 pt; 3.9 mm) too
> tall.  That suggests the header was prepended instead of overlaid.
>
> It looks like the /mm numbers are 3.85/mm and 7.70/mm; that would mean
> an a4 page should be 297.0 * 7.7 = 2287 pixels, making you tiff 35 px
> too tall, or 4.55 mm.  Still about right for a prepended header line.
>
> -JimC
Its worth noting that the FAX spec precisely defines the width of a 
normal sized FAX page as 1728 pixels, and its resolution as 204dpi x 
98dpi (196dpi for fine mode). However, it fails to specify the length of 
a any page type (A4, legal, etc) in pixels. This leads to various quirky 
behaviours between FAX equipment, where a page that is perfectly good 
according to one piece of equipment gets split into 2 pages by another. 
This probably stems from the fact that all early FAX machines used a 
continuous roll of paper, so specifying the exact maximum length of a 
page didn't seem important to them. Its sad that later revisions of the 
spec didn't introduce some guidelines on this topic.

Steve