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April 2012
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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