From: Joachim Oppenheimer (joachim@microdsi.net)
Date: 04/24/03-04:34:22 PM Z
I never cease to learn from you - I appreciate your useful comments. My next
computer will be a Mac. Joachim
-----Original Message-----
From: FDanB@aol.com [mailto:FDanB@aol.com]
Sent: Thursday, April 24, 2003 10:22 AM
To: alt-photo-process-l@sask.usask.ca
Subject: RE: Digital Negative CurvesThe Lost Transfer Function
Joachim said in his message...
>It is worth considering Harald Johnson's comments in his recently
>published "Mastering Digital Printing" on the subject of TRANSFER
>FUNCTION. He states that this was created to help printers compensate for
>dot gain and that it is seriously flawed in comparison to PS curves, chief
>of which is that there is no way to preview the image in transfer function
>(page 150).
You CAN preview the effect of a Transfer Function. Just Go to Curves in
Photoshop and click Load. Navigate to where you saved the Transfer
Function and Load it.
Note: Macs are smart enough to know that Transfer Functions and Curves
are really the same thing so you can load a Transfer Function in the
Curves dialog and, likewise, you can load a Curve in the Transfer
Function dialog. Very simple. Windows users have to jump through some
hoops (what's new).
If you want to preview a Transfer Function on a Windows machine, save the
T.F. with the .acv extension (used for Curves). Your PC will then be able
to see it (and load it) from the Curves dialog. Similarly, if you'd like
to load a Curve in the T.F. dialog, save the Curve with the .atf
extension (the Transfer Function extension).
For advanced readers and Photoshop nerds only: Now here's an arcane
anomaly. Because Curves can have up to 16 points but T.F. can only have
13, it's possible to design a wacky Curve that won't be accurately
reflected as a Transfer Function. So now you know the one and only REAL
reason Transfer Functions are inferior to Curves (talking
grayscale--let's not even get into color).
Hope this helps!
Dan (who thoroughly enjoys his never-crashing, never virus-plagued OSX box)
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