Re: [Gimp-print-devel] was - P700 and P900 full channel support

[Robert K. <rl...@al...>]

On 11/2/21 1:25 PM, Walker Blackwell wrote:
> Yes, but some people's motivations are much more elaborate: aka addressing individual channels for silk screens dye ink transparency printing, monochromatic ink sets, white inks, allowing for over-inking or under-inking (uncoated papers, fabric, etc). 

Exactly, and in the context of a printer app this is why we need all of the detailed ink options:
there are people who use them, and 32 options simply isn't enough to cover these use cases.  There's
no way the T-shirt people could print with IPP Everywhere.

In a lot of ways, I'm more concerned with these exotic uses than with day-to-day printing,
especially with IPP Everywhere and driverless printers.  These are niche markets, but they're
underserved and as we're not a business we're in a good position to support these use cases.

>> On Nov 2, 2021, at 8:22 AM, Michael Sweet via Gimp-print-devel <gim...@li...> wrote:
>>
>> FWIW, the P900 is an AirPrint printer, which means you should be able to use it out of the box without drivers using CUPS' IPP Everywhere support.  And it should support both sRGB and AdobeRGB like the P800...
>>
>>
>>> On Nov 2, 2021, at 8:06 AM, Walker Blackwell <fo...@wa...> wrote:
>>>
>>> I just got a P900 in-house. I gotta boot a linux machine and start cracking. . .
>>>
>>> I’m going to assume the P900 requirements are pretty close to the P800 (2 picoliter SureColor head though so maybe close to P600) but won’t know for sure until I get at it.
>>>
>>> Best,
>>> Walker
>>>
>>>
>>>> On Nov 2, 2021, at 3:00 AM, Oliver Kowalke <oli...@gm...> wrote:
>>>>
>>>> I checked out the git repo (branch master) and I started reading "The Developer’s Guide to Gutenprint".
>>>> Unfortunately I can not find the printers.xml as mentioned in the guide - instead ./src/xml/printers/escp2.xml contains the Epson models. Is this the correct file? Maybe the guide is not up-to-date?
>>>>
>>>> In ./src/xml/printers/escp2.xml the SC-P700 and SC-P900 is not listed. Does this mean that both models are not supported yet or is it the wrong file?
>>>>
>>>>
>>>> Am Mo., 1. Nov. 2021 um 23:47 Uhr schrieb Robert Krawitz <rl...@al...>:
>>>> On 11/1/21 1:29 AM, Oliver Kowalke wrote:
>>>>>
>>>>>    It should be possible to support this, other than the violet channel.  We could support the violet
>>>>>    channel for raw printing (i. e. the user has to do the separations), but actually supporting the
>>>>>    violet ink for normal printing would be a fair bit of tuning work and would need to be hands-on.  If
>>>>>    you're interested in doing this, be prepared to put a lot of time and a fair bit of consumables
>>>>>    into it.
>>>>>
>>>>>    The first thing to do would be to look at src/xml/escp2/inks/cmykrb.xml in the Gutenprint source
>>>>>    tree to see an example of what we did for the R1800 and R800, which is CMYK+red+blue (which is
>>>>>    actually closer to purple, but Epson calls it blue).  The most non-standard part of this is the
>>>>>    <Curves> section, which is a set of transfer curves for each ink channel by hue, starting with
>>>>>    blue=0.  I always tested these by printing a rainbow sweep pattern and trying to get as good of a
>>>>>    match as I could with ordinary CMY(K).
>>>>>
>>>>>    My thought about this is that we should at least at first only support the violet ink in raw mode,
>>>>>    as effectively a spot color.
>>>>>
>>>>> Your description applies to the violett channel?!
>>>>> Because I'm new to print driver development I'd like to start with supporting the matte black
>>>>> channel. At least I think it should be easier, right?
>>>>> What  would be your advice to start?
>>>>
>>>> The channel ID for matte black will probably be the same as it is on every other printer that uses
>>>> matte black.