[Openicc] colord 0.1.0 released!

[Robert Krawitz]

On Sun, 16 Jan 2011 13:35:19 -0800, Hal V. Engel wrote:
> On Sunday, January 16, 2011 12:18:18 pm Jan-Peter Homann wrote:
>> Hello Richard,
>> I´m not a developer, so may be my questions are in some cases a little
>> bit simple:
>> 
>> What is a device ?
>> for colormanagement in the printing chain, the printer profile has to be
>> assigned to combination of device/ink, paper and driver settings. How do
>> you solve this with colord / CUPS ? (predifined CUPS queues for every
>> combination of (device/ink, paper and driver settings?)
>
> This is a good question.  When I looked at the colord admin
> interface screen shot I didn't see anyway to specify these things
> and was going to ask about it.  Oyranos has had a lot of work done
> on this part of the printing work flow and I think that whatever is
> being done should leverage that work.
>
> In the CUPS ppd it is possible to specify one or more ICC profile to
> printer mappings that allows for specifying three things.  By
> default these are:
>
> Media type (IE. paper type)
> Resolution
> Color Model (RGB, CYMK...)
>
> Color model is mandatory but the other two can be changed to reflect
> other things like specific driver settings (IE. ink settings for
> example).  I am not sure why Color Model is mandatory or even needed
> since this can be determined by looking at the profile.
>
> Clearly being able to specify three things is not enough and I don't
> see where this issue is addressed with colord.  Would it be possible
> to give us more information on this?

I didn't comment on this in my previous remarks, but this is actually
a very important issue.  Three options simply isn't nearly enough for
Gutenprint.

We've been looking at whether and how to identify options that may
affect the color output.  Many options (including, of course, media
type, resolution, and color model, but also a lot more) affect the
color output, but there are other options (such as media size,
borderless/full bleed, unidirectional/bidirectional head movement)
that don't.  Would it be useful to be able to flag these options in
the PPD file somehow, and if so, how?

This is probably splitting hairs a bit too much, but there are some
options that shouldn't affect color output, but may to a small extent.
For example, high end Epson printers include an option to microadjust
the paper feed to get correct dimensions on different media types
(some people are very sensitive to fractional percent errors in
dimensionality -- if something's supposed to be 500 mm in length, and
it actually prints 502 mm in length, that's a problem).  This will
slightly affect ink density, although *probably* not enough to matter.

The upshot is that in general we don't want the key to be artificially
limited to a small number of options, but we also need to figure out
how to manage it in the common case that a lot of these options take
on default values.  Many of the things that affect color (such as ink
type -- CMYK vs. CcMmYK) are things that users don't normally change
from their defaults.