[Gimp-print-devel] questions

[<sh...@al...>]

Ok, so, I've more or less finished adding rudimentary support for all of the
documented Epson Stylus 750 commands to unprint.c.  I'm using the 6clr_99L1.PDF
file which is publicly available on Epson's website as my basis for the
escp2 language should be.  It's not a particularly well written document,
IMO.  It's got several places where it is inconsistant with itself.  It
looks like a case of careless cut & paste writing.  Anyway, I tried to use
common sense where the document appeared to lack it.  If the 750 truly
understands all of the older commands, then unprint.c should be able to
unprint any escp2 file (when finished).

So, I took a small jpg, ran it through the print plugin set to 720 DPI,
ESP750, softweave-mode, and pushed the resulting file back through unprint.

One of the first things I noticed was that it generated an unknown command
error.  gimp-print included an ESC ( K command.  What does this command
do?  It's not listed in my documentation.  Is there a better document
that describes this stuff, or, is this an undocumented feature?  Can we
make a document for undocumented features?

The other error it generated was a malformed page format error.  The
page format command ESC ( c should take a 4 byte format string, but
the one in the file is an 8 byte string.  What does the 8 byte version
of this command mean?


I also have some other, more general questions.  There are two ways to send
raster data to a 750.  Using "ESC i" or "ESC .".   The "." form include
a density number which lets you know what horizontal DPI the raster
data should be printed at, but, the "i" version does not.  What determines
the horizontal printing density for the "i" form?  I assumed that it
would be a function of the relative horizontal units being used.  This
probably relates to the page format specification uncertainty I mentioned
above.  And what exactly are the "page management units" good for?

There were a couple of other things I wanted to ask, but I think I'll wait
until I understand these, and then all may be clear.

Eric