[Openicc] printer, driver, CUPS, PPD, printing GUI, ICC-profiles, colord, Oyranos, taxi....

[Kai-Uwe Behrmann]

Mike,

first of all thanks for the detailed explanations. It helped a lot while 
reading the spec. My comments are below ...

Am 16.01.12, 09:06 -0800 schrieb Michael Sweet:
> [Keep in mind, everything that follows is part of IPP Everywhere and is not specific to CUPS]
>
> On Jan 16, 2012, at 8:39 AM, Kai-Uwe Behrmann wrote:
>> ...
>> How does a CUPS clients provide custom output profiles to the printer?
>> Along a IPP Job ticket?
>
>
> The currently published draft for the IPP Job and Printer Extensions - Set 3 (JPS3) is available here:
>
> 	http://www.pwg.org/ipp
>
> Printers can advertise a list of vendor or site-configured ICC color profiles in the printer-icc-profiles-supported attribute, which tells a client what profiles will be used by default when doing color transforms from non-device color spaces to the device color space for the job.  The client cannot specify which profile is used for a given job in the job ticket (see below).

How does the profile selection work react on user edited options 
like gamma, brigthness ...
In JPS3 I found only the: 5.6.22 printer-icc-profiles (1setOf collection)

> Printers can also advertise a list of rendering intents (the usual ICC stuff plus relative BPC) so that the client knows how those profiles will be applied during printing.  The client can specify which of those intents to use for a given job in the job ticket.

That looks good to me. Great to see "relative-bpc".

> These attributes allow the client to do soft-proofing (for example, in the print preview window/dialog of a client UI) and client-side color management (if you don't like the printer's CMS but do like its profiles).

These are all good things for useability. How does the spec adress your
considerations, which prevented to expose printer profiles in CUPS? 
(http://www.cups.org/str.php?L2894)

> If you want to use a custom profile (or if you are doing client-side color management), you just supply document data using a device colorspace (e.g. DeviceGray, DeviceRGB, DeviceCMYK, etc. for PDF or PostScript).

How does that interact with all of the legacy /DeviceRGB content? 
Specifically: will that new behaviour become a hard cut? Will the filters 
make a difference for device colour spaces depending on old style PPD API 
usage in CUPS and new IPP style submission?

My personal preference is to make a hard cut in not colour converting 
Device colour spaces and allow this way easier client side colour 
management, including relyable profile creation.

Can you confirm, this mechanism is only useful for PDF/PS? Jpeg, PNG and 
SVG have no means to mark colours as being in device space?

I asusme the PDF OutputIntent together with PDF/X/A/E will still work.

> If you want the printer to automatically use a custom ICC profile, the client sends a request to the printer (Set-Printer-Attributes) with the updated list of printer-icc-profiles-supported values.  That list becomes available to all clients of that printer...

Thats a great addition.

> Please let me know if the model we are using in JPS3 is not sufficient (and specifically why) as soon as possible since we are trying to lock down the technical changes for JPS3 for a working group last call in the coming month...

We like similiar mechanism like the PPD ColorKeyWords:
http://www.freedesktop.org/wiki/OpenIcc#PPD_colouring
A keyword like "print-color-keywords" should contain the names of those 
keywords, which are influental to colour like: media, resolution, 
brightness, gamma ...  Contrary, paper size is not colour related.
These informations are needed during profile creation and allow automated 
profile selection.

Having that keyword described inside JPS will cover the ICC requirements 
more completely. Please correct:

5.6.33 printer-color-attributes (1setOf type2 keyword)
The  RECOMMENDED "printer-color-attributes" Printer attribute lists 
all color related operation attributes that are influental to color 
appearance.

You mentioned a similiar to cupsICCProfile qualifier attribute, but I 
could not find it in JPS3.


kind regards
Kai-Uwe Behrmann
-- 
developing for colour management 
www.behrmann.name + www.oyranos.org