223 lines
9.0 KiB
HTML
223 lines
9.0 KiB
HTML
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 3.2 Final//EN">
|
|
<HTML>
|
|
<HEAD>
|
|
<META NAME="GENERATOR" CONTENT="SGML-Tools 1.0.9">
|
|
<TITLE>PPA Printer calibration for pnm2ppa</TITLE>
|
|
|
|
|
|
</HEAD>
|
|
<BODY>
|
|
Next
|
|
Previous
|
|
Contents
|
|
<HR>
|
|
<H1>PPA Printer calibration for pnm2ppa</H1>
|
|
|
|
<H2>The pnm2ppa project team
|
|
<A HREF="mailto:ppa-rpms@sourceforge.net">ppa-rpms@users.sourceforge.net</A></H2>v0.4, October 28, 2000
|
|
<P><HR>
|
|
<EM>Information and instructions
|
|
for printer calibration using pnm2ppa.
|
|
<A HREF="http://sourceforge.net/projects/pnm2ppa">http://sourceforge.net/projects/pnm2ppa</A>
|
|
(Updated for pnm2ppa-1.02 and later.)</EM>
|
|
<HR>
|
|
<P><B> Overview of Printer Calibration.</B>
|
|
<P>There are three main tasks you may need to carry out to fine-tune
|
|
your PPA printer:
|
|
<UL>
|
|
<LI>Adjust the x-offset and y-offset to <B>correctly center
|
|
the printed page on the paper</B></LI>
|
|
<LI>Adjust the relative offsets between black and colored ink
|
|
printing - <B>this should be done each time you replace an ink
|
|
cartridge</B>.</LI>
|
|
<LI> Match the colors of printed images to some other output device
|
|
- this is <B>color correction</B> and is
|
|
described in
|
|
<A HREF="./COLOR.html">COLOR.html</A> (or COLOR.txt).</LI>
|
|
</UL>
|
|
<P>These instructions assume that you are already able to print postscript
|
|
files with your PPA printer. If your print filters
|
|
are properly configured, something like "<CODE>lpr test.ps</CODE>"
|
|
will successfully invoke ghostscript and pnm2ppa
|
|
to print the postscript file test.ps. Alternatively, you may be using
|
|
shell scripts like "lprbw", "lprcolor"
|
|
and "lpreco" supplied with the
|
|
pnm2ppa source code, and modified by you for your defaults; you may also
|
|
have defined special printing devices in <CODE>/etc/printcap</CODE>, e.g.
|
|
a "coloreco" device so you print
|
|
with <CODE>lpr -P coloreco test.ps</CODE>. These details vary with
|
|
the operating system and distribution you use.
|
|
<P>
|
|
<P><B> (1) Centering the printed page on the paper. </B>
|
|
<P>This is done by adjusting the x-offset and y-offset parameters
|
|
<B>xoffset</B> and <B>yoffset</B>
|
|
in the <CODE>pnm2ppa</CODE> configuration file (usually
|
|
<CODE>/etc/pnm2ppa.conf</CODE>). The parameters are given in units of
|
|
1/600 inch; increasing <CODE>xoffset</CODE> moves the image
|
|
to the right, and increasing <CODE>yoffset</CODE> moves it downwards.
|
|
These offsets now have default values defined for each printer model,
|
|
and you will probably not need to adjust them.
|
|
Uncomment and make small adjustments to the default
|
|
values for these in the configuration file, until the printout is satisfactory.
|
|
(You can also use the '-x' and '-y'
|
|
command-line parameters.)
|
|
<P>
|
|
<P>There are two ways to check the offsets.
|
|
<UL>
|
|
<LI>either <B>using the "<CODE>calibrate_ppa</CODE>" program.</B> </LI>
|
|
<LI>or <B>printing a suitable test page</B>.
|
|
</LI>
|
|
</UL>
|
|
<P>
|
|
<P>The "<CODE>calibrate_ppa</CODE>" program is a
|
|
stand-alone program distributed with <CODE>pnm2ppa</CODE> which
|
|
creates various test patterns in the raw
|
|
pixmap format accepted by pnm2ppa. (The three paper sizes,
|
|
US Letter, US Legal, and A4, are supported).
|
|
If your paper size is A4, and your printer filter accepts
|
|
the "<CODE>-l</CODE>" (direct output) option to <CODE>lpr</CODE>,
|
|
the command to run is:
|
|
<BLOCKQUOTE><CODE>
|
|
<PRE>
|
|
calibrate_ppa -s a4 --center | pnm2ppa --bw -i - -o - | lpr -l
|
|
</PRE>
|
|
</CODE></BLOCKQUOTE>
|
|
|
|
(Substitute "letter" or "legal" for "a4" to change
|
|
the papersize; if no paper size is specified, it is assumed to
|
|
be <CODE>letter</CODE>.)
|
|
<P>
|
|
<P>
|
|
<P>If "<CODE>lpr -l</CODE>" is not valid, you need to know which port your
|
|
printer is attached to. Assuming it is <CODE>/dev/lp0</CODE>, the above
|
|
command becomes
|
|
<CODE> calibrate_ppa -s a4 --center | pnm2ppa --bw -i - -o /dev/lp0</CODE>.
|
|
<P>
|
|
<P>The pattern shows distances from the edge of the printed page
|
|
in units of 50 dots (1/12 inch), and diagonal lines that should
|
|
point to the corners. Change <CODE>xoffset</CODE> and <CODE>yoffset</CODE>
|
|
in the configuration file (usually <CODE>/etc/pnm2ppa.conf</CODE>
|
|
to center the pattern. The configuration file is
|
|
supplied with commented-out entries like
|
|
<CODE>#xoffset 160</CODE> showing the default value. Remove
|
|
the "<CODE>#</CODE>" to activate the entry.
|
|
<P>In Red Hat or Mandrake Linux distributions, a suitable test page is
|
|
<CODE>/usr/lib/rhs/rhs-printfilters/testpage.ps</CODE>
|
|
(US Letter paper) or
|
|
<CODE>/usr/lib/rhs/rhs-printfilters/testpage-a4.ps</CODE>
|
|
(A4 paper). (If these are not available, similar test pages
|
|
are supplied in the pnm2ppa source distribution.)
|
|
These pages have margins drawn at standard distances from the
|
|
edges of the paper, and can also be used to check the centering,
|
|
but are not as accurate
|
|
<P>
|
|
<P>
|
|
<P>
|
|
<P><B> (2) Calibrating the X and Y Color Head Offsets. </B>
|
|
<P>The color ink offsets now have to be calibrated with respect to the black ink.
|
|
Because the relative position of the two ink cartridges
|
|
can move slightly,
|
|
<B>this must be done whenever an ink cartridge is removed and replaced</B>.
|
|
<P>To print an alignment calibration pattern on a4 paper, run
|
|
<BLOCKQUOTE><CODE>
|
|
<PRE>
|
|
calibrate_ppa -s a4 --align | pnm2ppa --fd -i - -o - | lpr -l
|
|
</PRE>
|
|
</CODE></BLOCKQUOTE>
|
|
<P>On the printed page, there are four alignment patterns,
|
|
corresponding to configuration file
|
|
parameters <B>ColOffsX</B>, <B>ColOffsY</B>, <B>colorshear</B>
|
|
and <B>blackshear</B>. The central alignment patterns,
|
|
labelled "0" should be perfectly aligned. If they are
|
|
not, first
|
|
correct the shearing patterns, (see below).
|
|
Then identify the best-aligned <B>ColOffsX</B>
|
|
and <B>ColOffsY</B> patterns, and add or subtract the
|
|
positive or negative number below the pattern from the value in
|
|
the configuration file.
|
|
<P>Check the result by printing the alignment test pattern:
|
|
<BLOCKQUOTE><CODE>
|
|
<PRE>
|
|
calibrate_ppa --test | pnm2ppa -fd -i - -o - | lpr -l
|
|
</PRE>
|
|
</CODE></BLOCKQUOTE>
|
|
|
|
The lines in the cross and square should be perfectly straight now.
|
|
<P>The calibration can also be done by printing the test page
|
|
<CODE>test.ps</CODE> (found in the tarball
|
|
<CODE>pnm2ppa-1.0.tar.gz</CODE>; or installed
|
|
with the <CODE>pnm2ppa</CODE> documentation. (This is often in
|
|
<CODE>/usr/doc/pnm2ppa*/</CODE>.)
|
|
<P>On the printout you see several images:
|
|
<UL>
|
|
<LI>top left, you see a square with both black and colored items.
|
|
These should align correctly, or you have to change your settings.</LI>
|
|
<LI>You see a large vertical bar, and also a horizontal bar.
|
|
On the sides of the vertical bar there are a blue and a green line.
|
|
These should align with the 0 mark.</LI>
|
|
<LI> You also see a small vertical, and horizontal, bar, with a
|
|
red bar on its side.</LI>
|
|
</UL>
|
|
<P>If these items do NOT line up, you should take the following steps:
|
|
<UL>
|
|
<LI>(1) take for the large bar the number of the tickmark just smaller
|
|
than the place where the green and blue lines point to. The minor
|
|
tick marks are 25 points.</LI>
|
|
<LI>(2) To this number, add the number of the tick mark at which a red tick
|
|
mark exactly lines up. This might not work if the offsets are way off;
|
|
in that case, apply the correction of step 1, and print again.</LI>
|
|
<LI>(3) Add the horizontal offset to the value
|
|
of <B>ColOffsX</B>, and the vertical offset to
|
|
the value of <B>ColOffsY</B> in the configuration file.</LI>
|
|
</UL>
|
|
<P>Now you can print test.ps again to see whether this procedure worked.
|
|
<P>
|
|
<P><B>Shearing adjustments</B>
|
|
<P>If bidirectional printing causes "shearing" of vertical lines
|
|
(horizontal offsets of those parts of the line printed
|
|
by left-to-right print-head sweeps relative to those printed on
|
|
right-to-left sweeps) you can make small adjustments (in 1/600 inch)
|
|
units using the <B>blackshear</B> and <B>colorshear</B>
|
|
parameters in the configuration file. You can also suppress
|
|
bidirectional printing with a <B>unimode 1</B>
|
|
configuration file entry.
|
|
<P>The third and fourth lines on the color head offset calibration page
|
|
(see above) correspond to color and black print head shearing corrections.
|
|
If the central alignment patterns (labeled "0")
|
|
are not aligned, add or subtract the positive or negative number
|
|
below the best-aligned pattern from the <CODE>colorshear</CODE>
|
|
and <CODE>blackshear</CODE> values in the configuration file.
|
|
<P><B>Cleaning the Print Heads</B>
|
|
<P>You can use <CODE>calibrate_ppa</CODE> to clean the print heads by
|
|
printing patterns that exercise all the ink nozzles:
|
|
<BLOCKQUOTE><CODE>
|
|
<PRE>
|
|
calibrate_ppa --clean | pnm2ppa -p -i - -o - | lpr -l
|
|
calibrate_ppa --clean | pnm2ppa --bw -i - -o - | lpr -l
|
|
</PRE>
|
|
</CODE></BLOCKQUOTE>
|
|
|
|
The first of these commands prints a cleaning pattern
|
|
with colored ink, the second uses black ink.
|
|
<P>
|
|
<P><B>Other adjustments</B>
|
|
<P>The parameter <B>blackness</B> adjusts the number of black ink
|
|
drops printed per pixel. It takes values 1, 2, 3, or 4 (2 is the
|
|
default). Other values, like 0, suppress black ink.
|
|
<P>Inks can also be suppressed by configuration file
|
|
entries
|
|
<CODE>black_ink 0</CODE>,
|
|
<CODE>color_ink 0</CODE>,
|
|
<CODE>cyan_ink 0</CODE>,
|
|
<CODE>magenta_ink 0</CODE>,
|
|
or <CODE>yellow_ink 0</CODE>.
|
|
These are mainly useful for debugging
|
|
the printer driver.
|
|
<P>
|
|
<HR>
|
|
Next
|
|
Previous
|
|
Contents
|
|
</BODY>
|
|
</HTML>
|