RE: CMYK separations on Adobe Photoshop

You print the Red channel with cyan, the Green with Magenta, and the
Blue with Yellow.
It sounds crazy but it's true!!!
Cheers
Kate

-----Original Message-----
From: gdimase@hotmail.com [mailto:gdimase@hotmail.com]
Sent: Saturday, 30 October 2004 4:48 p.m.
To: alt-photo-process-l@sask.usask.ca
Subject: Re: CMYK separations on Adobe Photoshop

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? Giovanni

----- Original Message -----
Wrom: ZXUWLSZLKBRNVWWCUFPEGAUTFJMVRESKP
To: <alt-photo-process-l@sask.usask.ca>
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
>
> >>> jsmigiel@kvcc.edu 10/29/04 8:56 AM >>> mgalanmolina@hotmail.com
> >>> 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
>
>

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