Re: CMYK separations on Adobe Photoshop

From: [email protected]
Date: 10/29/04-09:48:24 PM Z
Message-id: <>

Sorry, but...
How do you get the Cyan channel from a RGB file without going to CMYK?
Isn't this the question?
How do you get the Cyan colors?

----- Original Message -----
To: <>
Sent: Friday, October 29, 2004 10:22 AM
Subject: Re: CMYK separations on Adobe Photoshop

> I forgot to mention a fairly obvious thing: once you have the channel
> saved as a positive grayscale file you have to invert the positive to a
> negative. This can be done under Image--> Adjustments-->Invert or by
> having the printer set to invert the files during printing. I also flip
> the image horizontally when printing so that the ink surface is next to
> the emulsion of the paper.
> By sheer coincidence, yesterday and today I have been testing separation
> negatives made for gum printing on a new Epson 2200 printer using both
> the CMYK mode and the RGB method I described earlier. I'll scan the
> prints as soon as they dry today and put them online. Once on the web,
> I'll post the URL in case you wish to see a visual comparison of the
> results of both methods.
> Joe
> >>> 10/29/04 8:56 AM >>>
> >>> 10/29/04 5:57 AM >>>
> Hi list, there is a easy way, or not easy, to make cmyk separations on
> photoshop other than change image mode to cmyk. I want to obtain the
> separation channels as layers in order to apply curves over every layer
> independently and save it as different files.
> Thanks
> Manuel, from Spain
> Wih an RGB file (e.g., image.psd), open the channels window and select a
> channel. For example, select the red channel. Then change the mode to
> grayscale and discard the other channels. At this point, ***be sure to
> rename the file*** (e.g., image_RED.psd). You now have a grayscale
> positive of the Red channel and you have the original file still intact.
> Do the same with the other channels (G+B). Then, using the original
> file, change the mode to grayscale (or desaturate the RGB file) and
> rename it for the black channel.
> Be aware that this set of negatives will be distorted in terms of color
> printing characteristics compared to those made using the CMYK mode and
> selecting those individual channels for negatives. The info preserved
> just isn't the same, but can be interesting nontheless.
> Also, why not use the channel mixer (Image-->Adjustments-->Channel Mixer
> IIRC) to get the effects you desire in RGB and then switch to CMYK and
> print out the separations?
> Joe
Received on Fri Oct 29 21:49:07 2004

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