RE: [hpoj-devel] Success with G85

[PASCHAL,DAVID (HP-Roseville,ex1) <dav...@hp...>]

Allen Barnett wrote:
> I installed 0.8 of the OfficeJet drivers per the very detailed
> instructions in the README files and have successfully 
> scanned from, and
> printed to, a G85 connected through its USB port.
Hi, Allen.  Thanks for your success report.  I'm glad it works for you.
However, I should point out that this is not version "0.8" yet.  My
references to "0.8" on the "Bugs and TODO" page are meant to indicate what
still needs to be done before the code will be ready for me to create and
release a new official package, which will be numbered "0.8".  I can't give
a definite date for that yet but at this point I think June or July is a
realistic goal, given the large amount of new code I just checked in (and
code I still need to write) and the time it will take to work out all the
problems.  Nevertheless, all the testing you can do on the "unstable" code
in CVS will be greatly appreciated.  :-)

Regarding the "very detailed instructions", do you think they are too
detailed in the README/INSTALL/*-HOWTO files?  I'm thinking they are and
that I should provide simpler (less detailed) setup instructions there and
move most of the details into separate manual pages for each daemon or
application.  Do you have any thoughts one way or the other?

How was your experience with updating printer.c in the Linux kernel source
(if you weren't already running a recent-enough kernel)?  I'm trying to
decide if I need to provide a sufficiently up-to-date version with the hpoj
package so people don't have to mess with downloading and updating their
kernel (or just extracting that file).

> It takes a relatively long time (~4.5 minutes) to scan at 600 dpi. The
> head moves a little bit forward, then backs up a couple of times, then
> goes a little bit further. Is this normal behavior? (Lower 
> resolutions,
> even 300 dpi, seem to zip right through).
The higher the resolution, the more data that needs to be transferred.  At
some point as you increase the resolution the I/O becomes the bottleneck,
rather than the scanner, so the scan-head backtracking you observed is to be
expected.  600dpi is overkill for most applications anyway.  I'm not an
expert on the subject, but I think 150dpi is probably sufficient for photos.
There are various "scanning FAQs" available, though I don't know where
offhand.  I think the on-line documentation to the "xsane" frontend
application has references to some of these.

> (Also, what's the 
> best tool to
> look at a 107Mb TIFF file :-)
For simple viewing I used to use "xv" until RedHat stopped providing it.  I
now use Electric Eyes ("ee"), but I created a xv->ee symlink because I was
so accustomed to typing "xv".  :-)

> The RedHat printtool test page shows the red hat logo and a set of
> sample colors. The red in the "red hat" is a reasonably 
> bright, however
> the red in the sample color bar is much too dark. I guess this is a
> gamma problem, but why would the two reds look so different? 
> Presumably,
> the red in the logo is from a PostScript bitmap and the red 
> in the color
> sample is just a filled rectangle. Is one gamma correction going to
> affect both?
You might get slightly better results by tweaking the gamma correction, but
I don't think it will help much.  The new drivers under development by HP at
http://hpinkjet.sourceforge.net should provide much better output when
they're released.

When I print the RedHat test page on a PostScript Color LaserJet 4500, the
colors come out correctly, but there is a slight difference between the two
reds.  RGB->CMYK color mapping is hard to do, and a slight difference on one
output device can be greatly magnified on another device using a
less-optimized mapping.

> Finally, what does MLC stand for?
Multiple Logical Channels.  MLC is an HP transport protocol for packetizing
multiple data streams, such as printing and scanning, over a single link,
such as parallel or USB.  1284.4 is an IEEE standard based on MLC.

> Many, many thanks to David for making this available.
You're quite welcome; I'm glad it's useful to you.  Thank you for your
interest and feedback.

David