Re: Article on Photoshop CS4 and DeviceLink profile
Re: Article on Photoshop CS4 and DeviceLink profile
- Subject: Re: Article on Photoshop CS4 and DeviceLink profile
- From: Koch Karl <email@hidden>
- Date: Wed, 03 Dec 2008 16:02:48 +0100
Chris,
Am 02.12.2008 um 20:22 schrieb Chris Cox:
Wow. Someone should have done some fact checking before sending
that out.
I did quite some fact checking before sending this out and I can back
all of my factual statements. My opinions, though, are subjective, as
is the nature of opinions ;-)
Yes, there are a lot of corrupt multichannel profiles out there -
mostly from older profile makers that didn't test interoperability.
Adobe applications do check for profile validity before offering the
profiles for use. So, not all of your installed multichannel
profiles may show up in Photoshop - because they may not be valid
profiles.
Strangely enough, these profiles work well in other applications (not
only those which created them). ColorSync Profile Repair doesn´t mark
them as invalid or corrupted, either. I admit that these were old
v2.0.0 profiles, not really state of the art.
The PhotoYCC profile is interpreted correctly - but the result is
YCC, displayed as a multichannel document.
I never doubted that the profile is interpreted correctly in the B2A
direction, it´s just A2B that sucks or in other words, is not
suppoerted.
There currently is no way to provide realtime previews or display of
multichannel profiles with more than 4 channels - so Photoshop opted
to get users the basic functionality requested (making separations)
and use the existing multichannel mode. The preview during the
conversion is limited by what is in the multichannel profile plus a
few limitations of how Photoshop creates the preview (it could be
improved, but it'll take a lot of work).
Accepted.
Um, yeah - most multichannel profiles don't have enough information
to correctly convert back to the original data.
Agreed. You will never get back to the original data. But there are
users out there who have the crazy wish to print proofs from
multichannel data, so they need to go from multichannel to proofer
CMYK (or RGB).
And you're in multichannel mode without any information about the
destination colorspace.
This I don´t understand. As far as I thought I had understood the
innards of Photoshop, you always have the information of your monitor
color space which acts as a destination colorspace.
The author should spend some time reading about how multichannel
mode in Photoshop works (it is not a new thing).
OK, so it´s the same old mechanism, just pimped with a multichannel
profile conversion.
Abstract profiles convert through the PCS. The source and
destination can easily be the same profile (like the current
document profile).
Agreed – "can" but doesn´t necessarily have to, except in Photoshop 11
where the user doesn´t have the choice.
Abstract profiles are used to "change the look" -- that's what
they're for.
I think I understood that much.
The author seems to think they have some other purpose, but does not
explain what that purpose might be.
Maybe it´s a problem of not being a native English speaker. I thought
I had made myself clear. And I asked some precise questions which you
didn´t bother to answer:
"When you select a rendering intent, where is it applied? On the way
from working space to PCS, on the way back, or in both directions? I
haven´t found out yet. If you want to apply the abstract profile on
the way from your working space to an output space, you need to
transform another time – you lose flexibility and each transformation
costs image quality."
Nothing was goofed up for device link profiles. The primary demand
for them was CMYK->CMYK (for print), and RGB->RGB (for non-print
folks). Adobe has a limited number of engineers, a limited number
of testers, and a limited amount of time to develop and test
features. Rather than delay support of device link profiles until
time became available to test every possible combination of input
and output color mode, Adobe focused on what was requested by the
users to solve real world problems.
Also, yes, after a device link conversion document remains in the
original colorspace, because currently devicelink profiles do not
contain information about the destination profile so that Photoshop
could assign the correct profile after applying the device link.
AFAIK it was Adobe who requested a new tag in ICC profiles (pseq) that
provides exactly this information. So, why don´t you use the
information for applying the correct profile after applying the device
link WHEN it is there?
The ICC has recently approved standards to improve the situation,
but there were no samples available to test that before Photoshop
shipped.
Maybe you should have asked basICColor ;-) (this was not meant as
advertising!)
The author seems to have drawn several bad conclusions from a severe
lack of knowledge, and a failure to do background research on the
topic. This article is worse than useless, it is seriously
misleading.
I´m always eager to learn. Unfortunately your anwers to my article didn
´t really enlighten me. There is no new information and nothing that
would make me take anything back. I´m not quite as dumb as you seem to
believe.
What magazine was this published in?
It´s not yet published, I wrote, I had written an article, not that I
had had one published.
And was it correctly labeled as advertising for basICColor?
Because I mentioned, that there is a solution out there? That doesn´t
have Adobe´s name on it? Being the CEO of basICColor GmbH, I take the
liberty to mention solutions that are working, although they bear the
basICColor brand.
The article was not about Adobe-bashing. I wanted to warn the
Photoshop 11 users of some pitfalls when working with the "new" type
of profiles. Especially the device link conversions are error-prone.
Not every user out there will understand that she/he will have to
assign a different profile after a device link conversion. Converting
again (e.g. to a proofer space) without having done so will wreak havoc!
The multichannel support is only half-hearted and the abstract profile
support is a pragmatical approach – at best.
Best regards,
Karl Koch
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basICColor GmbH
Maistraße 18
82377 Penzberg - Germany
phone: +49-(0)8856-932505
fax: +49-(0)8856-932503
email: email@hidden
http://www.basICColor.de
Managing Director: Karl Koch
Registered Office: Penzberg
Commercial Register: 172485, AG München
VAT No. DE814946213
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