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Re: 16 bit quadtone process PhotoShop 5 Action



 Hisun wrote:
>Dan, I have getting good result from the PS5 Action. But I cannot apply
>the curve, otherwise the light tones will be gone. I simply do not use
>any curve. =20
>
>The black channel is not selected after the Action is completed. If it
>is not, the printed image is not as black. Is there a way for me to
>change the Action so that the last step is change to "Multiply" and
>select the Black Channel as well?

Hello Hisun,
If using the final curve adjustment "*layer* in the first action makes the
final CMYK file too light then undo the steps of the action (using the
history palette) and run it again.  This time when you load the curve
called "B-16 bit sep curve b.ACV" make it a bit darker by dragging the
curve a bit.  It may take a little bit of adjustment to get the curve right
for your images.  I've preadjusted the CMYK composite curve to preserve
shadow detail and for some images you will need instead to preserve
highlights more. You might want to save a few versions of this curve for
different image types. If you *never* use this first curve, however, you
will not have a very well separated set of channels.  The first curve is
necessary or you will really not have much more than four exact copies of
the original grayscale file with some light inks removed from the dark
tones.  This will print but it will not eliminate the dark inks from the
light tones and you will have black ink spots in the highlights.  This
first curve is essential to eliminate this. The second curve (the curve
layer used after the action is complete) is entirely optional and is
sometimes not necessary. But if you use it you should adjust each channel
separately, not use the CMYK composite curve.  The image at this point has
been separated into tonal zones by ink density and if you want to darken
the highlights you would use the Cyan channel (25% ink) all by itself, or
with a little bit of the yellow (50% ink) darkened as well.   If the total
ink gets too high however, you may have to add another adjustment layer
(channel mixer) to remove some more of the light inks from the dark
channels or drop the dark side of the black or magenta channel inks to
lighten the overall image.  On some images it can get rather complex trying
to optimise both highlights and minimize total ink.  With this type of
image it is easiest to use a paper like Sommerset Enhanced which can take a
rather heavy ink load.

For the second action (which converts the CMYK file into an RGB (K) file) I
haven't quite yet figured out how to make it select Multiply for the right
layer in the action.  It is definately still a Beta copy.  Somehow I made
it so that it sets the opacity of the background layer to 25% instead of
the Background Copy layer. In fact, it seems to do something different
every time it runs!   But selecting Background layer after the action has
ceased and resetting it to 100% and then selecting the "Background Copy"
layer and then setting the mode to multiply and 25% is fairly easy.
Whenever I fix this I'll resend the action (probably Rev C by then!).

Dan Culbertson




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