multichannel => duotone

I received a 2-channel image with the intention to create a duotone PDF or EPS file, subsequently converted to PDF thru Distiller or Ghostscript.
Since the only way i know to convert a multichannel image in a duotone is converting all channels to grayscale, merging and applying the duotone, thus losing all colour infos, is there another way to convert a 2-channel image in a duotone without losing color information for every channel?

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il Clod!/
ICQ UIN 97056271

In article <1i2v7iwkspr3p$>,
ilClod wrote:

Since the only way i know to convert a multichannel image in a duotone is converting all channels to grayscale, merging and applying the duotone, thus losing all colour infos, is there another way to convert a 2-channel image in a duotone without losing color information for every channel?

No. A duotone image is nothing more than a black and white image printed twice in two different inks.

Are you sure that you need to make a duotone, rather than using the image as it is? Many people--especially people inexperienced in prepress--say "duotone" when they mean "spot color"--is it possible the person who gave you the original image made this error and does not actually want a duotone?

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Art, photography, shareware, polyamory, literature, kink: all at http://www.xeromag.com/franklin.html

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On Mon, 11 Apr 2005 10:23:13 GMT, ilClod wrote:

I received a 2-channel image with the intention to create a duotone PDF or EPS file, subsequently converted to PDF thru Distiller or Ghostscript.
Since the only way i know to convert a multichannel image in a duotone is converting all channels to grayscale, merging and applying the
duotone, thus losing all colour infos, is there another way to convert a 2-channel image in a duotone without losing color information for
every channel?

Sure. Copy the composite layer first! :-)
Then: Channel mixer set to monochrome, apply Image|Mode|Grayscale, then Image|Mode|Duotone.

Want more control, more advanced?
How about a dutone, Johnny's way? <g>

Make two copy layers of the composite channel (RGB or CMYK). Set the blending mode on "layer 1" to "normal", and the blending mode of "layer 1 copy" to "overlay".

Use a channel mixer adjustment layer on each new layer (group with
[previous] layer), and use grayscale output (check the monochrome
box).

Make a second adjustment layer to each, above each channel mixer layer, group with previous adjustment layer, and make it a hue/saturation layer, with the "colorize" box checked.

Hide the bottom layer (probably the background), select all and copy merged, new layer as copy, to get a new "flattened" layer. This is your duotone layer.

Now just do a File|New(from clipboard)|Paste, then flatten and save. Voila! Duotone image.

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-john
wide-open at throttle dot info

Il Mon, 11 Apr 2005 14:05:02 GMT, Tacit ha scritto:

Are you sure that you need to make a duotone, rather than using the image as it is?

I'm sorry for my bad explaination. I still have some "foggy" ideas about this project.
Well, i need both spot colours, so i think it is not necessary a real duotone as you define it. Actually it's about "two-plate printing" (hope it's a clearer, if not better, definition :-)
IIRC EPS3 file format supports both duotone and multichannel plates. But if i try to export a two-channel image, i get a DCS file (even if its extension is EPS). So, if i import it in, say, InDesign, i can export a PDF with both channels, and that's fine. But i can't do it if i export a DCS from PhotoShop, so i can't distill it to get a PDF. And I wanted to skip this "layout" step.

Many people--especially people inexperienced in
prepress--say "duotone" when they mean "spot color"--is it possible the person who gave you the original image made this error and does not actually want a duotone?

Well, actually i'm not so experienced about prepress, but i'm trying to learn as fast as i can :)
The fact is, have to design a pricelist booklet for a customer, and, listening to his requests, i thought duotone was fine. But when i received this file i noticed it wasn't as easy as i might think. If i continue using InDesign there's no problem. But i also would like to find a less "trickier" way to get a PDF from a multichannel image

Thank you so much by now :-)

--
il Clod!/
ICQ UIN 97056271