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Re: Apple raster, PWG raster and non-free filters/drivers

Apologies for the delayed response but at the time I had nothing of
interest to say. After some research, (and the Christmas/New Year
period), I think have.

On Wed 21 Dec 2016 at 18:52:28 -0200, Till Kamppeter wrote:

> On 12/21/2016 05:27 PM, Brian Potkin wrote:
> >This was a main part of what I wanted. I think you are saying that if
> >avahi-browse shows image/pwg-raster the rule-of-thumb would indicate it
> >is an Everywhere printer.
> >
> Yes, that is what I wanted to say:
> image/pwg-raster -> IPP Everywhere
> image/urf        -> AirPrint
> >That still leaves (for me) the lack of information in a vendor's
> >literature. Taking the Lexmark CS720de as an example. It's specs do not
> >mention pwg, so how is a user to know it could be an Everywhere printer?
> >How did you get to learn it had image/pwg-raster support?
> I know about this only from my phone call with Aveek Basu from Lexmark. He
> has used this printer to test my newest developments. He simply installed
> all the latest and greatest following instructions which I have sent him and
> said printer showed up supporting image/pwg-raster. After setting it up
> using the driverless methods it ended up printing PDF because it also
> understands PDF and PDF is the preferred format.
> This means that the current printing stack auto-detects driverless printers
> and uses them as such, but if you did not buy the printer yet you still do
> not know whether it works driverless if the manufacturer does not tell so.

Basically, a user needs to know whether the printer will accept PWG
raster. From a cursory reading of the Developer Guide for Printers and
Connectors at


it would seem that PDF and PWG raster are the formats that a Google
Cloud Print Ready printer should accept. I cannot work out whether PDF
is the preferred format to send when a printer supports both but (like
AirPrint-capable printers having to support Apple raster) it would not
be unreasonable to assume PWG raster *has* to be present on the device.
PDF does not appear to come with most low-end printers so that makes it
likely that all printers claiming to be GCP-compatible would do PWG
raster. The Lexmark CS720de does claim this.

Unless a manufacturer takes the time and trouble to self-certify a
printer for IPP Everywhere use there is no way of knowing how much of
IPP it supports without trying it. But, thinking on, printouts should be
reasonablely good if the manufacturer has done a good job for GCP.

That is my contention, then. You can be confident "GCP Ready" gets you
PWG raster on the printer. And this can be known beforehand.


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