Re: [Gimp-print-devel] The Truth Behind ESC ( D

[Robert L K. <rl...@al...>]

   Date: Thu, 2 Mar 2000 10:42:53 -0500
   From: Karl Heinz Kremer <kh...@kh...>

   > The ESC (D command is supposed to be "secret".  That is, we
   > cannot release information on it without a Non-Disclosure
   > Agreement.  However, by looking at a description of the command,
   > I cannot justify withholding it. It doesn't make sense to me that
   > knowing how to use this command will allow the public in on a
   > trade secret of any kind.  If anything, it will allow us to
   > capitalize on the talents of the Linux community to develop
   > better drivers for us.  Our liaison from Japanese HQ agrees with
   > me.  So here is the info you wanted.

Well, this is a win for everybody concerned, or at least for Epson,
Linux users in general, and us.  I'm glad to see Epson taking steps
like this.  This will definitely give them a competitive advantage
(until the other printer companies figure out that doing this is in
their best interests, too).

   > ESC (D nL nH rL rH v h			[Set resolution of raster image]
   > nL=04H, nH=00H
   > 0<=v<=127
   > 0<=h<=127
   > vertical resolution is v/(rH*256+rL) inch
   > horizontal resolution is h/(rH*256+rL) inch
   > available resolutions are (depending on model):
   > 	1/120, 1/180, 1/360, 1/720, 1/1440

Very interesting.  From two output samples from a 750 (one at 720, and
one at 1440), I got this:

00000083  1b  (  D 04 00 40 38 78 28 

These numbers correspond to

r = 14400
v = 120		(1/120", or 6 rows)
h = 40		(1/360")

Both a 640 and a 740, at 720 dpi, give the same numbers.

Another printer (a 900, I think), gives:

00000083  1b  (  D 04 00 40 38 28 28 

That corresponds to v = h = 1/360".

Somebody else (might have been me) reported these results:

> 1) ESP750, 1440 DPI:	00000083  1b  (  D 04 00 40 38 78 28 
> 2) ESP750,  720 DPI:	00000083  1b  (  D 04 00 40 38 78 28 
> 3) ESP900,  360 DPI:	0000008a  1b  (  D 04 00 40 38 28 28 (grayscale)
> 4) ESP900,  720 DPI:	0000008a  1b  (  D 04 00 40 38 28 50 (grayscale)
> 5) ESP900, 1440 DPI:	0000008a  1b  (  D 04 00 40 38 28 50 (grayscale)

There's something here that doesn't make a lot of sense.  Why on earth
does anyone need to *set* the printer resolution, anyway?  Isn't it
fundamentally a property of the printer hardware?

-- 
Robert Krawitz <rl...@al...>      http://www.tiac.net/users/rlk/

Tall Clubs International  --  http://www.tall.org/ or 1-888-IM-TALL-2
Member of the League for Programming Freedom -- mail lp...@uu...
Project lead for The Gimp Print --  http://gimp-print.sourceforge.net

"Linux doesn't dictate how I work, I dictate how Linux works."
--Eric Crampton