[Leaplist] HP1100 under XP slow to print some PDFs

[John Simpson]

On 2007-11-07, at 1021, Jason Boxman wrote:
>
> I have a HP1100 that's glacially slow to print some PDF files.  I  
> don't know
> what's special about them, but they may take three or three minutes  
> per
> page.  Being a moderate PPM printer, it can otherwise print quite a  
> few
> pages each minute.

remember what a PDF file actually is- it's a collection of drawing  
primitives. if you decrypt, decode, and interpret the contents of a  
PDF file, it looks something like this:

- unit is "points"
- paper size is 612 horizontal, 792 vertical
- drawing area is (36,36)-(576,756)
- use font "Courier 10 regular"
- move to (36,744)
- draw text "Hello world!"

most of the drawing primitives are self-explanatory. however, one of  
the operations you can do in a PDF file is "draw image". and just as  
"move to" requires coordinates, or "draw text" requires a string of  
characters to draw, the "draw image" command requires an image. which  
is usually sent as a TIFF, because that's the easiest format for a low- 
powered CPU to decode into a bitmap.

so think of it this way: there are two types of PDF file. one contains  
text, along with instructions on where to put the letters, what fonts  
to use, and any line-drawing or simple shapes or shading patterns to  
draw. the other type, which is normally generated by "scanner"  
programs, consists of a description of the page size and a single  
"draw image" command.

so even though it may have a ".pdf" name, it's just a container around  
one or more TIFF files.

many printers support a language called "postscript", which is the  
same basic commands you find in a PDF file, but spelled out in more  
detail, using a backwards notation similar to the RPN notation that  
many scientific calculators use. where a PDF file might say 'move to  
(36,744)' followed by 'draw text "Hello"', in postscript it might look  
like "36", "744", "scale to physical page coordinates", "move cursor",  
"courier", "10", "regular", "select built-in font", "string 'Hello  
world!'", "draw text".

for a real postscript printer, a "printer driver" can print a PDF file  
by translating each PDF command in to a series of postscript commands,  
and letting the printer do all the work. for a PCL printer (like the  
HP1100), it can translate most of the commands from PDF to PCL, and  
the printer does its thing... but bitmaps have to be sent as images,  
with each pixel's colour (or shading level, for a greyscale printer)  
specified.

if a page in the PDF file contains a bunch of text primitives, the  
driver sends PCL text-drawing commands to the printer. if the page  
contains an image, it has to send that image to the printer, one pixel  
(or group of pixels) at a time.

if you have acrobat or something else which can create PDF files, try  
this:

- pull up a document of some kind, with a half-page or more of text.

- "print" that document to a PDF file.

- print that same document to a real printer.

- take the printed output, and scan it back into the computer. don't  
use OCR or anything, just tell the scanner software to "save as PDF  
file".

- compare the sizes of the two files.

> I am considering buying one of those moderately inexpensive print  
> servers
> you plug into the parallel port or USB port of the printer,  
> providing you a
> network-aware printer, so I can spool there.  The Windows print  
> spooler
> reports document sizes from 500K to several MB when printing these  
> PDFs.

i'm using my HP1100A (the one with the scanner/copier attachment on  
the front) with an HP170X print-server box. the only problem i've  
noticed, and i've seen this on the HP1100 with other print servers, is  
that every so often the printer stops responding to print jobs-  
apparently the print server thinks the printer is offline, even though  
it's not. the button on the front of the printer doesn't help, the  
only way to fix it is to pull the power cord on the printer, wait a  
second, and plug it back in.

and if somebody wants to jump my case for helping with a "windows  
related" question on the linux list... i have personally seen the same  
issue (some PDF files taking forever to render and/or print) with  
windoze (as far back as 98SE), linux, and mac osx, so as far as i'm  
concerned, it's on-topic.

besides, what does it hurt to be polite and answer a simple question  
once in a while, especially for a regular? (provided the question  
doesn't demonstrate blatant mental laziness, of course... we all know  
there are limits, but this question didn't even come close.)

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| John M. Simpson    ---   KG4ZOW   ---    Programmer At Large |
| http://www.jms1.net/                         <jms1 at jms1.net> |
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