Image Help - - Colour separations for duotones

Lidia2 · #1 09-03-2004, 02:22 AM

Hi guys, would really appreciate some advice or a nudge in the right direction to go to find out. I've just done a poster as a favour for my friend's theatre production company all in Photoshop 7...it was originally going to be printed digitally but due to quantities they went for offset printing last minute. Now I know absolutely nothing about the process and the printers have been on to me every day with new problems and I'm struggling to understand what they want me to do. The file I supplied to them was full A1 size, not flattened and 2 colour in content (black, white and red). Trouble is on the red image (a feather) where there's shading I think what they're saying is that they can't print the various shades and have said I need to supply them with .tif files, consisting of 2 layers each and colour separated to black and red. Can anyone please tell me (as simply as possible please) what it is I actually need to do, I've spent hours on the poster and typical of me concentrated on making it 'pretty' without having a clue that there was a whole technical world to take into consideration with it....help please!

Lidia, New Zealand

Hunter · #2 09-03-2004, 09:38 AM

Well, I must say I'm a bit confused - since when can TIFs have layers?

Let's back this all up a bit. You say you want to print this in 2 colors, but then you mention 3 colors: "black, white, and red."

Duotones (or monotones, tritones, quadtones) as I understand them (and I make no claims at being the supreme font of knowledge here) would be where you're specifying the color range to be made up of two specific Pantone colors. Say I wanted a "warmish" photo. I'd change my color mode of my photo from 24-bit RGB to Duotone (which is 8-bit, BTW) and select Pantone Process Black and Pantone Warm Gray 8 as my two colors - of course you would tweak the tone curve of the two colors to whatever you like.

This would then be saved off as either an EPS or a DCS (desktop color separation) file - ask your printer which one they need.

Of course you could choose other color swatches, too, but these colors are applied to the entire photo, not specific areas. Duotones are usually used when you're printing in a publication that has been limited to two specific spot colors. "White" is not a color in these instances, it's an illusion. The shading is achieved by various percentages of the ink values. Pantone 1585C is a somewhat "pumpkiny" orange color at its full 100% value. But if I wanted to place text in a photo that had was using this as its color base and I needed the text as "white", I could not use "white" as a color for the text as that would make the color separators think I was printing in CMYK plus a spot color and thereby increasing my print costs. So what you would do is to create your text and use the color 1585C *but* mark it as using 0%, which would essentially be white.

So.... if you really are trying to print a duotone where you have a background as one PMS (Pantone Matching System) color and a separate object as a second PMS color, what you'll probably need to do is have two separate files. One file will be your "background" file with an area cut out (clipping path/alpha mask) where your feather will be, the other file will be your "feather" with the background cut out/alpha masked out. Each file will need to be exactly the same size. Double-check with your printer again, because if it is a real duotone, I do believe it will have to be an EPS or DCS file format and not TIF.

I hope this is what you were meaning by "duotone" and I've not just rambled on incessently

Lidia2 · #3 09-03-2004, 03:17 PM

Thanks so much for coming back Hunter. The printers are calling it a duotone as apparently black doesn't count for a colour (I designed in RGB thinking it was straightforward to just convert to whatever they required as they originally told me that for 2 colour printing a CMYK file was no good anyway) . The poster is black background, white text and a stylised large red feather (with shading on it to give it some depth) and I think that's where the problem is. Where the black shading lying along the veins of the feather creating shadows on feather vary slightly in tone in a browny red and where the highlights fall on the feather the colour is a blood red. The pantone colour I supplied them for the red was 485c (or DS 74-1C) as they didn't tell me what material they were printing to, anyway it's a blood red colour and I'm happy for them to match to as closely as possible. They definitely said to do 2 layers but think I read somewhere that the word layer may mean something else to a printer (it's all double Dutch to me). What I don't get is why they keep sending the file back to me asking me to do something different every time, (last time they asked me to resend a full size photoshop file with layers and now they've come back saying they can't print at all because of the red), surely they should be able to do what they need to do their end even if they charge for it or is that not reasonable? I really appreciate you taking time out on this one thanks Hunter as you can see I really don't understand the process too well and the printers are shouting deadlines. One last thing although they haven't mentioned supplying an EPS file can you explain what advantage this has? I'll give the 2 file thing a go though so thanks for that.

Lidia

Flora · #4 09-04-2004, 04:12 AM

Hi Lidia,

Quote:

Originally Posted by Lidia2

(it's all double Dutch to me)

...well...that makes the two of us .....

Anyway, I had a look at the Photoshop Help files under: Printing duotones where you can find a link to: Printing color separations .... where you can find a link to: Saving files in Photoshop EPS format (Photoshop)

... Don't know if this can be of any help, though ....

Doug Nelson · #5 09-04-2004, 08:43 AM

It sounds like there's some miscommunication going on. A "duotone" is an image printed with two different colors of inks. PS has some very advanced controls over this, and it's a very complex subject.

But I've found a lot of people (incorrectly) call all images separated for offset printing duotones. I've even come up against this while talking with pre-press experts. So just keep in mind it could be their ignorance, and not just yours.

It sounds like they either want a separated CMYK image (the EPS), or (since you're specifying a Pantone color) separated spot-color plates. "Spot color" is the offset term for any ink that isn't cyan, magenta, yellow, or black.

It sounds like they're asking for two channels, one for the black and one for the red. If you compose it with one black layer and one red layer, I'm sure they'll be able to use it. (which, by the way, would actually be a duotone, since there's only two colors of ink, black and red).