Re: ensuring no conversion
Re: ensuring no conversion
- Subject: Re: ensuring no conversion
- From: Chris Cox <email@hidden>
- Date: Fri, 26 Dec 2008 15:05:02 -0800
- Acceptlanguage: en-US
- Thread-topic: ensuring no conversion
That is not "fooling colorsync" - that is what is required by the Apple printer and ColorSync APIs (we worked with Apple quite a lot on that) when the application does the color conversion (otherwise it is likely to be converted again). But Epson's ABW printing has a bug - it expects all data in gamma 2.2, regardless of what the driver says. Until Epson fixes their ABW code, you'll need to preconvert the image to a gamma 2.2 colorspace (like sRGB). Hopefully Epson will fix their driver bug soon so users won't have to keep manually applying the workaround.
In 90% of cases, the printing in Photoshop CS4 and LR2 is working correctly. But in about 10% of drivers, the manufacturer has failed to update the driver to Tiger or Leopard standards, or has bugs with their profile handling. In every problem case that we know of, Adobe and Apple filed bugs with the manufacturers, and are eagerly awaiting bug fixes from those manufacturers. But the code in Photoshop and Lightroom are doing exactly what Apple and Microsoft say they are supposed to be doing.
Chris
Message: 1
Date: Thu, 25 Dec 2008 09:37:31 -0300
From: "Roy Harrington" <email@hidden>
Subject: Re: ensuring no conversion
To: "Tyler Boley" <email@hidden>
Cc: email@hidden
Message-ID:
<email@hidden>
Content-Type: text/plain; charset=ISO-8859-1
Currently it seems CS4 and LR try to fool ColorSync
by tagging the output with the Generic profile so colorsync
stays out of the way. Trouble is that it fails in some
cases '-- in particular with B&W output i.e. QTR and
Epson ABW. There is also a complication in that
colorsync can also apply a real print profile.
(its a bit of a mess in my opinion)
Roy
On 12/23/08, Tyler Boley <email@hidden> wrote:
> Eric, Roger, and Roy, thanks for your input. The current situation is for
> from ideal, and of course further issues remain, for example if the OS only
> hands tagged "Generic" off unaltered, one wonders what is going on with
> Photoshop managed data tagged with output profile. Of course I know what
> should happen, and what happened for years, but confidence is lowering
> lately.
> Tyler
>
>
>
> Eric Chan wrote:
> > Tyler and Roger,
> >
> > Unfortunately this is not a long-term solution. It assumes, for instance,
> that Apple will be substituting Generic RGB and Generic Gray as the default
> profile in case the printer driver does not register a profile. That is true
> for 10.5.x (Leopard) but will not be true of 10.6 (Snow Leopard), when Apple
> will switch to using sRGB as the default profile. As you know, sRGB uses a
> gamma encoding that is approximately 2.2, whereas Generic RGB & Generic Gray
> of 1.8 gamma encodings. Thus you would still need to provide users with
> system-specific information, e.g., "If you are on 10.5.x, do this ... and if
> you are on 10.6.x, do that ..."
> >
> > The real solution is to get all the clients (i.e., printing applications
> and printer drivers) fully compliant with the latest Apple printing APIs so
> that users don't have to resort to these (fragile) workarounds. Some apps
> and drivers are already there, but others require an update.
> > Eric
> >
> >
> >
> > > To me, any DeviceRGB_X to DeviceRGB_X should result in a
> > > null conversion. But is that always the case, provided a
> > > RelCol rendering intent? I can't say for sure but it seems
> > > the way to go. I agree.
> > >
> > >
> >
> >
> > >
> > > > If I have an RGB chart (or anything RGB I want to print
> > > > un-managed to consider raw output), if I assign "generic
> > > > RGB", have Photoshop manage colors, and then select
> > > > "generic RGB" again for output profile, can I force a
> > > > null conversion, and insure a tag OSX feels all warm and
> > > > fuzzy about passing on to printer drivers unaltered?
> > > >
> > > >
> > >
> >
> >
> >
> >
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