Re: Regarding opening untagged images (long post)
Re: Regarding opening untagged images (long post)
- Subject: Re: Regarding opening untagged images (long post)
- From: Joel <email@hidden>
- Date: Tue, 24 Jul 2001 17:10:50 -0500
Since the list is on summer vacation I thought I would add another
thread I've been mulling over whilst wobbling through
AdobeUserForums>ColorManagement
Veli asked:
Joel, you say that you open the raw scan by assigning Adobe RGB, and
then convert it to Adobe RGB, i.e. both ends of the conversion
procedure is the same color space. Why?
joel answered on the AdobeUserForum:
The actuals you get are only relative to:
A.> the accuracy of your monitor profile (for softpreview)
B.> the monitor profile relationship to actual file data (for
softpreview/editing)
C.> the file data's relationship to your output profile (for
editing/conversion)
D.> the accuracy of your output profile. (for conversion/printing)
E.> the maintainance state of your printer (printing)
So... same color space? Let's address B and C as A has been bypassed
(Veli is roughly using Adobe Gamma for monitor profiling).
*"One can change the meaning of the numbers in the file as far as
Photoshop 6 is concerned (AssignProfile), or one can actually change
the values of the pixels (Convert to Profile)."(Andrew Rodney
...methinks)
I happen to have a multitude of clients, each with their own specific
workflows and I flip flop wildly. I make no mistakes by Converting.
Why? No variables. Just actuals.
ASSIGN simply tags without converting data (thus x=1 where the variable is 1).
CONVERT changes the data and assigns a tag (thus x=1).
The variable results because Assign Working RGB "is directly
analogous to opening up a particular RGB image in Photoshop 5, then
going to the RGB Setup and changing the Working Space, thus changing
the meaning of the RGB numbers." (Andrew Rodney)
Meaning:
OPEN OPTIONS fall into place like this:
(Option 1) Do Not Color Manage is not recommended.
(option 2) If you Assign Working RGB the Assigned(unsaved) file
varies according to your RGB setup.
(Option 3a) If you use Assign a Profile and do not convert, you have
tagged-only and a variable still exists until you save. You end up
saving, in essensce, an unconverted file which opens again as a
converted file, yet no true conversion has taken place.
(Option 3b) If you Assign then Convert the file is not bound by other
variables and it's preview relationship is profile-to-profile. (Note:
some RGB files contain more data than a monitor profile can display.)
I just take Option 3b one step further by doing my own conversions
because I like to watch (nudge nudge wink wink) and...
...what does it leave you with?
Convert displays x (actual data) against the accuracy of your monitor profile.
Assign displays how your RGB color setup renders variable data
according to your monitor profile.
Working with actuals enables you to eliminate variables and move on
in your troubleshooting:
See actuals (A thru E) above and break it down:
A: your monitor profile is currently a variable thus eliminates both
A and B, therefore softproofing and accurate editing (WYSIWIG) is not
attainable.
C: is only as actual as the fixed values of your data. You know that
conversion from C (Input) to D (output) is only as accurate as to
what you establish as C, thus Convert is arguably more actual than
Assign. You know that conversion from C (Input) to D (output) is
only as accurate as your conversion rendering intent (I prefer
Relative Colormetric with Black Point Compensation) and the accuracy
of D (your Output Profile) and the CMM engine used, thus, if you put
C in a position of being an actual value and your profile-to-profile
is sound, you can move on to...
D: is a 'canned profile' (Veli is using Epson and Epson canned
profile) the accuracy is only relative to conditions which existed at
the time and place for the creation of that profile and the specific
device(s) it was created on; but it is better than nothing. The only
cure for canned profiles not doing the trick is to create your own or
subscribe to a service which does that for you.
E: it's a good idea to regularly clean your printer.
It's also a good idea to read a bunch of stuff... :}
PS: the differences in Assign Working RGB (AdobeRGB), Assign
(AdobeRGB) with no conversion, Assign and then Convert (AdobeRGB) can
be viewed by 2d graphing transformed target tiffs using Steve Upton's
ColorThink 1.1
http://www.chromix.com
Though the differences are slim, they are there nonetheless.
Anyone care to jump in?