[Openicc] new: Proof colour space setting
Kai-Uwe Behrmann
ku.b at gmx.de
Wed May 3 02:52:42 PDT 2006
Hello Ann and all,
the idea of mine was to define a system wide proofing colour space, a
profile, which can be used by applications as a predefined and optional
activated profile for poofing on screen and print out. The proofing
profile settings set and activate the simulation of a film stock or a
intended printing condition (SWOP/ISOcoated).
Your idea is more about a single colour space, like PhotoGamut(?), in
differenence to a general system setting.
Sorry if my head line was missleading you. I changed the head therefore.
Of course feel free to continue this interessting toppic.
For the "proofing profile setting", hope this makes a difference now, I
decided to add it to the Oyranos configuration settings.
kind regards
Kai-Uwe Behrmann
+ development for color management
+ imaging / panoramas
+ email: ku.b at gmx.de
+ http://www.behrmann.name
Am 02.05.06, 14:36 -0400 schrieb almccart at lexmark.com:
> Hi Jan-Peter and all,
>
> I would agree that it needs to be a free choosable color space that is
> independent of
> scanner, camera, monitor, types of RGB spaces and that is also independent
> of any
> particular CMYK. Note that Adobe RGB is a monitor type of RGB even though
> it is
> wide gamut.
>
> Yes - I was thinking that a proofing color space would be an intermediate
> between the
> source color spaces [e.g., Adobe RGB, camera Raw RGB] and particular print
> related
> output spaces. One question is how constrained should the gamut be?
> Should it be
> limited to a SWOP-like gamut? Or be like the ISO reference gamut - which
> is a bit larger.
> Another way of thinking about it is -- Would you want a proofing color
> space to contain
> the Pantone colors? Or to be limited to a subset of Pantone colors as many
> real print
> systems are?
>
> I think you got the idea I was putting forth. My question is - is that
> what you and Kai-Uwe
> had in mind?
>
> Best regards,
> Ann McCarthy
> Lexmark CPD
> Imaging Systems Engineering
> ICC Workflow WG Chair
>
>
>
>
>
> Jan-Peter Homann <homann at colormanagement.de>
> 05/02/2006 01:41 PM
> Please respond to homann
>
>
> To: almccart at lexmark.com, OpenICC Liste <openicc at lists.freedesktop.org>
> cc:
> Subject: Re: [Openicc] new: Proof colour space
>
>
> Hello Ann, and all,
> Nice to hear, that leading ICC members are reading and posting to the
> openICC list :-)
>
> I think, your answer is two steps ahead, of the mail of Kai-Uwe.
> As I understand him, he want the possibility of a free choosable
> proofing colorspace independent from the RGB- or CMYK-workingspace in
> ICC aware open source applications.
>
> As I understand your concept of an "proofing colorspace" as an
> intermediate colorspace between widegamut colorspaces like
> camera-profiles on RAW data or AdobeRGB and printoutput.
>
> Finetuning of colors and saturation is done in the "proofing
> colorspace", if the work is done, gamutmapping from "proofing
> colorspace" to print output colorspace needs and can be done either with
> relatice colorinteric and blackpoint-comepnesation or with ICCv4
> perceptual gamutmapping, if the gamut of the "proofing colorspace" is
> similar of a better "reference medium gamut" for ICCv4 profiles.
>
> Do I understand your intentions correct ?
>
> :-) Jan-Peter
>
> almccart at lexmark.com wrote:
> >
> > Hello Jan-Peter and all,
> >
> > So -- if we were to define a 'proofing colorspace' what would the
> > requirements be?
> > For example:
> > 1. RGB encoding
> > 2. Encompassing and similar in shape to the ISO printing gamut defined
> > in ISO 12640-3 Annex B
> > 3. Not significantly larger than the ISO printing gamut defined in ISO
> > 12640-3 Annex B
> > 4. Unambiguously defined transformations to/from CIE XYZ
> > 5. Primaries placed so that if the file is incorrectly assumed to be
> > sRGB, severe hue shifts do not occur.
> > 6. Primaries placed so that HVS response to tone and hue adjustments are
>
> > reasonably homogeneous
> > throughout the space [i.e., perceptual isometry].
> > 7. Adapted white point, color space white point and black point
> > chromaticity = D50
> > 8. Print-referred image state
> > 9. Adapted white point and color space white point luminance: 160 cd/m^2
>
> > [=ICC PCS]
> > 10. Image surround - 20% of adapted white point
> > ...?
> >
> > Does this represent a good initial list of attributes?
> > Is there an existing public domain RGB that meets these criteria?
> >
> > Best regards,
> > Ann McCarthy
> > Lexmark CPD
> > Imaging Systems Engineering
> > ICC Workflow WG Chair
> >
> >
> >
> >
> > *Jan-Peter Homann <homann at colormanagement.de>*
> > Sent by: openicc-bounces at lists.freedesktop.org
> >
> > 05/02/2006 07:41 AM
> > Please respond to homann
> >
> >
> > To: Kai-Uwe Behrmann <ku.b at gmx.de>
> > cc: OpenICC Liste <openicc at lists.freedesktop.org>
> > Subject: Re: [Openicc] new: Proof colour space
> >
> >
> >
> >
> > Hello list,
> > A proofing colorspace would be very helpful.
> > I know several photostudios, which are dealing with agencies, prepress
> > bureaus and print shops.
> >
> > They are working in RGB and deliver RGB and CMYK-Files (ISOcoated) to
> > their clients.
> >
> > Before they are converting to CMYK (ISOcoated) with relative
> > colorimetric and blackpoint compensation, they do a proof and optimize
> > the RGB-file, if colorclipping of saturated colors are occuring.
> >
> > The goal is to build an archive of RGB-files, where all RGB-files can be
> > converted relative colorimetric with blackpoint compensation to the main
> > destination colorspace, without the need to make image by image
> > analysis , which rendering intent fits best.
> >
> > Most uzsers I know prefer to have a special menue for softproofing,
> > instead of doing it in the colorsetting file.
> >
> > Very helpful is also, if the softproof menue is synchronized with the
> > menue "convert to profile"
> >
> > If the softproof is OK, the file can be converted to the destination
> > colorspace with one mouseclick.
> >
> > :-) Jan-Peter
> >
> >
> > Kai-Uwe Behrmann wrote:
> > > Hello list,
> > >
> > > what would you think about a dedicated proof colour space?
> > >
> > > The current situation in CinePaint is: we have RGB/Cmyk image data
> > and can
> > > proof them to whatever colour space on screen. If someone wants to
> > > simulate an special output device like a film stock or a print media,
> it
> > > seems there is no sense by sticking to the editing colour spaces
> > > (RGB/Cmyk). It is not clear if the user wants a RGB or Cmyk colour
> space
> > > to proof against.
> > >
> > > It could as well mean the proofing options should become a separate
> > > advanced configuration group.
> > >
> > > Whats the opinion on the list about this matter?
> > >
> > > regards
> > > Kai-Uwe Behrmann
> > > + development for color management
> > > + imaging / panoramas
> > > + email: ku.b at gmx.de
> > > + http://www.behrmann.name
>
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