Dan Margulis Applied Color Theory
The Uses of Multichannel Mode
Date: Mon, 05 May 2003 22:43:22 -0400
From: Susan E. Hoffman
Subject: Grayscale - adding spot color
I work for a small newspaper and we are mainly B/W but
we get one spot color each week for the front/back spread.
I had something come up at work today and I think I
should have been able to resolve in Photoshop but for some reason I could
not figure out how to do it. I have a piece of grayscale line art (drawing
of a rose) and I want to print one spot color with this artwork in CMYK
(that is, color the rose cyan and leave stem and leaves B/W). My thought
was to make the cyan somewhat transparent so that the black line art would
show through.
First I opened it in Photoshop and converted to CMYK,
but I end up with 4 channels, and I am thinking I don't need the M and Y,
but when it converted to CMYK, it turns out that all 4 channels would
combine to make the black. I tried ditching the 2 unneeded channels but the
black channel alone was not strong enough without the MY. At that point I
was not sure how to do what I wanted, so I ended up going into Illustrator
instead (which maybe I should have done in the first place), and creating a
separate C layer to color above the original B/W line art and that seemed
to work OK.
But ... is there a way to do what I was starting to do
in Photoshop, and how would you suggest I approach this?
Susan E. Hoffman
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Date: Tue, 06 May 2003 08:57:31 -0000
From:Stephen Marsh
Subject: Re: Grayscale - adding spot color
Susan, I would probably do this -
i) Grayscale > Multichannel
ii) Add three _white_ channels to the single channel
file
iii) Drag the original K channel to the last or bottom
or fourth position in the stack.
iv) Multichannel > CMYK
v) Add the data to the C channel that is being used in
lieu of spot channel data.
Multichannel is _the_ mode to think of when moving
between spaces and you need to keep the original channel data intact.
Regards,
Stephen Marsh.
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Date: Tue, 06 May 2003 08:58:07 -0400
From: Lee Clawson
Subject: Re: Grayscale - adding spot color
Susan,
From grayscale file (1 Channel) convert to
"multi-channel" mode. Add 3 more
channels. The 1st channel here later becomes the cyan
channel (CMYK). If you
want it be the black channel drag it to 4th place. Then
convert to CMYK
mode.
Lee
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Date: Tue, 06 May 2003 10:51:41 -0400
From: david ridderhof
Subject: Re: Grayscale - adding spot color
Susan,
Another method.
Start with grayscale image. Background color should be
white.
Select all, copy. (Command A, Command C)
Mode, convert to CMYK.
Command 1 (cyan channel) Delete (clears to white) or
Paste ( Command V. puts
full grayscale data in Cyan channel)
Command 2 (magenta) Delete
Command 3 (yellow) Delete
Command 4 (black) Paste (Command V). This
puts the full grayscale data in the
Black channel.
Command ~ (tilde) This brings back the CMYK composite.
This can be done quickly with the key commands.
If you pasted into the Cyan, you have CK duotone and
need to delete the info
from each channel as desired.
If you left the Cyan channel white and are looking to
add a cyan tint behind
the black, select the cyan channel from the channel
palette, turn the eyeball
on next to the CMYK channel and paint with default
foreground black, fill with
a selection, etc as desired.
David Ridderhof
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Date: Tue, 06 May 2003 20:24:24 -0400
From: Susan E. Hoffman
Subject: Multichannel
Stephen, thanks a million for this suggestion. It is
exactly what I should have done! (I may still have time tomorrow to do this
before press time.) I've never used multichannel before and am glad to get
this tip.
What else does multichannel do, or in what other
situations might you use it?
Susan E. Hoffman
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Date: Tue, 06 May 2003 08:00:50 -0700
From: Mac Townsend
Subject: Re: Grayscale - adding spot color
While you could manage it in cmyk, as suggested, it
would be easier to use multi channel. using a magenta as a spot is in this
case not really different from using a pantone color.
But, and this is important, you cannot then save the
file as a jpg or tiff. you will need to save it as a dcs. i suggest dcs
multiple file, color tiff preview, binary encoding. This will produce (in
your case) 3 files, xxx.eps (which is a low resolution composite to be used
as the "placeable" image) and a xxx.m (magenta separation) and
xxx.k (the black separation). Spot colors will use xxx.1...2.3.4., etc. ALL
3 are essential because the application will need the separation files when
printing.
Mac Townsend
Adcom Graphics, Digital Imaging
Fairfield, California
www.adcomgraphics.com
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Date: Tue, 06 May 2003 20:33:14 -0700
From: David Creamer
Subject: Re: Grayscale - adding spot color
I have a piece of grayscale line art (drawing of a
rose) and I want to
print one spot color with this artwork in CMYK (that
is, color the rose cyan
and leave stem and leaves B/W). My thought was to make
the cyan somewhat
transparent so that the black line art would show
through.
But ... is there a way to do what I was starting to do
in Photoshop, and how
would you suggest I approach this?
Select all and cut the grayscale image
(you should have a totally white document now)
Convert to CMYK
Select the K channel and paste
Select and cut the parts of the image you want to the
cyan channel
(removing them from the K channel)
Save as TIFF
Also, here is how to make a "real" Pantone
spot color:
Select all and COPY the grayscale image
Go to the channel palette
Add a new alpha channel
Double-click on the new channel icon
Convert the alpha channel to a spot color channel
Click on the color box and select the Pantone color of
choice
Set the opacity to 100% (this is for preview only, it
does not affect print)
Make sure the spot channel is selected and paste
Erase the non-color parts of the image from the spot
channel
Switch back to the gray channel
Erase the non-black parts of the image
(if any of the colors overlap, the spot color will
overprint the black)
Save the file as DCS2
Place in page-layout program
(Note: DCS2 files to not work well when making PDFs
from your page-layout
program)
David Creamer
I.D.E.A.S.
http://www.IDEAStraining.com
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Date: Wed, 07 May 2003 11:42:00 -0400
From: Terry Wyse
Subject: Re: Grayscale - adding spot color
on 5/6/03 10:51 AM, david ridderhof wrote:
Another method.
And another:
1) Open grayscale image.
2) <Select all> and <Copy>.
3) <Command+N> for new image, change mode to CMYK
(check for proper resolution and dimensions but it should be fine) and
press <OK>.
4) Go to Black channel <Command+4> and
<Paste>.
You should now have a new CMYK image with your
grayscale image pasted in the K channel and blank CMY channels.
Terry
--
__________________________________
WyseConsul
Color Management Consulting
v 704.843.0858
__________________________________
________________________________________________________________________
Date: Wed, 07 May 2003 10:50:50 -0000
From:Stephen Marsh
Subject: Re: Multichannel
Stephen, thanks a million for this suggestion. It is
exactly what I should
have done! (I may still have time tomorrow to do this
before press time.)
I've never used multichannel before and am glad to get
this tip.
What else does multichannel do, or in what other
situations might you use
it?
Hi Susan, as suggested by another list member - the
good old copy/paste of the K channel before going into CMYK, then paste
into the K can be good - then clean the CMY up (yet another way to remove
unwanted CMY channel data is with a curve, making the CMY shadow endpoints
0%).
Multichannel is good in that more than one channel can
be handled at once, so it is not as critical for monotone originals.
Where Multichannel really gets a workout is in
converting a Duotone mode file into a spot channel file for use as a EPS
DCS 2 file. This is the bulkiest of modes - the same data in MC mode should
be bigger than in GS mode (don't know why, perhaps less efficient
encoding).
I personally do not often use MC mode for final
delivery of data - unless I have to, for me it is a transition between
modes and it is rare that spot channel jobs do not have a CMYK or Grayscale
parent file instead of Multichannel (most spot work is with K or CMYK inks
and not pure spot only).
The help guide will also fill you in on the 'pitfalls'
to using this mode and is worth a read or two.
Hope this helps,
Stephen Marsh.
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Date: Wed, 07 May 2003 13:08:34 -0700
From: Jono Moore
Subject: Re: Grayscale - adding spot color
on 6.5.03 8:00 AM, Mac Townsend wrote:
But, and this is important, you cannot then save the
file as a jpg or tiff.
you will need to save it as a dcs. i suggest dcs
multiple file, color tiff
preview, binary encoding. This will produce (in your
case) 3 files, xxx.eps
(which is a low resolution composite to be used as the
"placeable" image) and
a xxx.m (magenta separation) and xxx.k (the black
separation). Spot colors
will use xxx.1...2.3.4., etc. ALL 3 are essential
because the application will
need the separation files when printing.
Just wanted to post a warning about DCS files. They
work fine if you are using a pre-separated workflow (ie: separating from
Quark) but don't work in a composite workflow (in RIP separations or colour
lasers) unless you convert them to a proper EPS file with a program like
DCSMerger.
Why Adobe went with DCS files for this application no
one can figure out...It's old technology.
...Jono
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Date: Wed, 7 May 2003 16:48:26 -0700 (PDT)
From: Horacio Peña
Subject: Re: Grayscale - adding spot color
A very quick way to do a Cyan/Black image is:
1- convert the grayscale to CMYK
2- open the Hue/Saturation dialog
(Image/Adjust/Hue/Saturation)
3- check Colorize and move the Hue slider to 180
degrees. You should now see a blueish image. You can
increase/decrease the amount of Cyan with the Saturation Slider (more
saturation, more Cyan). You can control the amount of Black with the
Lightness slider (more lightness means less black).
Verify that the Magenta and Yellow channels are empty
and save your CMYK file. When printing, use only Cyan and Black Plates.
With different angles (Hue slider) you can get 2 or 3
colors images easily (I use 20 degrees for sepias).
Best Regards
Horacio
=====
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Horacio Peña
- Argentina
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Date: Thu, 8 May 2003 02:44:35 +0100
From: Christian Macey
Subject: Re: Re: Multichannel
Hi list,
Adding to Stephen's previous suggestions, multi channel
mode is also a good way to split a duotone file, into seperate
greyscale channels, so I can apply individual curves-to each colour
if needed.
HTH,
Christian Macey
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Date: Wed, 07 May 2003 17:32:36 -0700
From: Mac Townsend
Subject: Re: Grayscale - adding spot color
Yup. Old Tech, but what else can be used for bitmaps
with Pantone colors, such as scanned logos and such? Nothing else. Unless
you want to trace them and muck about with them in a draw program.
Why Adobe went with DCS files for this application no
one can figure
out...It's old technology.
...Jono
Mac Townsend
Adcom Graphics, Digital Imaging
Fairfield, California
www.adcomgraphics.com
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Date: Thu, 08 May 2003 08:20:41 -0700
From: Mac Townsend
Subject: Re: Re: Multichannel
Adding to Stephen's previous suggestions, multi channel
mode is also a
good way to split a duotone file, into separate
greyscale channels, so
I can apply individual curves-to each colour if needed.
Christian Macey
You can do this already, in the duotones box
Mac Townsend
Adcom Graphics, Digital Imaging
Fairfield, California
www.adcomgraphics.com
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Date: Thu, 08 May 2003 09:22:07 -0700
From: Jono Moore
Subject: Re: Grayscale - adding spot color
on 7.5.03 5:32 PM, Mac Townsend wrote:
Yup. Old Tech, but what else can be used for bitmaps
with Pantone colors, such
as scanned logos and such? Nothing else. Unless you
want to trace them and
muck about with them in a draw program.
If the guys that made DCSMerger can make a proper L3
EPS file out of a
Photoshop DCS file why can't Adobe? ;-)
...Jono
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Date: Fri, 9 May 2003 02:30:22 +0100
From: Christian Macey
Subject: Re: Re: Multichannel
Hi Mac,
I should of explained myself better. Not only can you
edit the individual spot colour channels with curves etc which I think is
an added bonus, you can also use painting tools to mask out a specific
colour area if required.
Then save as DCS 2.0.
Christian Macey
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Date: Fri, 09 May 2003 07:49:09 -0700
From: Lanny Lathem
Subject: Re: Re: Multichannel
on 5/8/03 8:20 AM, Mac Townsend wrote:
you can do this already, in the duotones box
This is true; however, when an image is converted to
multichannel mode from duotone mode, selections can be made that will allow
one to adjust the curve on portions of the image in each channel. This is
impossible with a duotone.
Lanny Lathem
Bennett Graphics
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Date: Fri, 09 May 2003 10:34:29 -0700
From: Mac Townsend
Subject: Re: Re: Multichannel
ah! yes.
Hi Mac,
I should of explained myself better. Not only can you
edit the
individual spot colour channels with curves etc which I
think is an
added bonus, you can also use painting tools to mask
out a specific
colour area if required.
Then save as DCS 2.0.
Christian Macey
Mac Townsend
Adcom Graphics, Digital Imaging
Fairfield, California
www.adcomgraphics.com
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