Re: Mitsubishi printers

Solomon Peachy <[email protected]> Wed, 20 Apr 2022 15:47:41 -0400
Newsgroups	gmane.linux.printing.gimp-print.devel
Message-ID	<[email protected]>
On Tue, Apr 19, 2022 at 07:25:07PM -0500, Matt Broughton wrote:
>    The user has a Mitsubishi CP-D70DW-S printer.  It is said to be a 
>    System model made for a kiosk.  Is this printer supported by 
>    Gutenprint? 

Yes, it is, as of... March 2020.

> The News for v5.3.4 says there is now support for the 
>    CP-D70DW-S but cups-genppd.5.3 doesn't have it as an available 
>    model. 

The 5.3.4 tarballs were uploaded in December 2020, so tha should be good.

BTW, the D70-S and D707-S models did not get different USB IDs or 
iProduct strings; they need to be detected at runtime based to the 
response to a special query, which enables a few minor tweaks to the 
command stream when printing thigns. They also do not accept the same 
media kits as the non-S variants.

> Also, is there a way to test the gutenprint53+usb backend 
>    without a printer?  That would be of great benefit in 
>    troubleshooting. Matt

There are some test modes, but it's mostly limited to printjob parsing 
and validation.  Anything requiring communication to the printer is 
bypassed.  (I have a CI setup that validates the backend against 
gutenprint's output for every supported model, with a stragetic set of 
print options)

That said, as I already mentioned in the forum discussion, the other 
thing these Mitsubishi models require to print is the "image processing 
library" needed to convert the 8bpp RGB output of gutenprint to the 
14bpp CMY gamma/thermal-corrected data the printer needs.  (All but one 
of Mitsubishi's color photo printers for the past decade have required 
host-side image processing)

I reverse-engineered Mitsubishi's algorthms and re-implemented them in a 
runtime-loaded GPLv3 library that lives outside of the Gutenprint 
repository.  I did it this way to protect both myself and Gutenprint in 
case Mitsubishi went all squirrely.

For Linux users, it's been easy enough to compile this for themselves, 
but this doesn't help folks on MacOS -- but at the same time, I've not 
generally cared about MacOS as Mitsubishi has historically provided 
drivers for that platform.  Notwithstanding special variants (-S, etc)

More recently, Mitsubishi has exited the printer business, so it might 
be worth revisiting the decision to keep this library and data files 
separate, bundling it with the rest of Gutenprint.

(FWIW, a similar-in-spirit, external run-time loaded library is also 
 needed for two Sinfonia printers..)

 - Solomon
-- 
Solomon Peachy			      pizza at shaftnet dot org (email&xmpp)
                                      @pizza:shaftnet dot org   (matrix)
High Springs, FL                      speachy (libra.chat)

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