Re: ensuring no conversion
Re: ensuring no conversion
- Subject: Re: ensuring no conversion
- From: "Roy Harrington" <email@hidden>
- Date: Sat, 27 Dec 2008 22:50:05 -0300
Hi Chris,
Maybe "fooling colorsync" isn't the best term. But as the author of
QuadToneRIP
which does grayscale printing exclusively, there appears to be no way to keep
ColorSync from converting whatever comes out of PS/CS4. On the PS print page
you can select either Photoshop or Printer Manages Color (No Color Management
is NOT selectable) and in both cases ColorSync will convert whatever you send
it to Generic Gray. This nullifies whatever profile is applied by Photoshop.
Being the author of QuadToneRIP I know that it has no color management info
whatsoever -- its a pure OSX CUPS driver that takes standard
rasterized input which
hasn't any profile info left by then. Whether this is the exact same issue as
Epson ABW I can't tell for sure. I do know that QTR has worked perfectly in
this regard with PS 7, CS, CS2, CS3 on Jaguar, Panther, Tiger, Leopard. Only
CS4 and LR has introduced this problem.
I've very interested in getting this to work for QuadToneRIP. If
there is something
else I should or could be doing, I'd really like to know.
Thanks,
Roy Harrington
On Fri, Dec 26, 2008 at 8:05 PM, Chris Cox <email@hidden> wrote:
> 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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