Duotone Problems

[berniebernie]

First of all having 2 colors is a black and white image without any gray tones (reaally rough image)

You can achieve duotone look with color gradients (just use a gradient with only two colors). Remember duotone is used for printing plates and is just there to have accurate colors. It's not really meant as an 'effect' for your image...

[Swizzle]

True, you can get a look similar to duotone with gradient maps. But there's a huge problem with that. Generally you're going to work in RGB color mode in Photoshop, but when you're preparing an image for printing you will almost always work in CMYK mode to achieve the most accurate print colors. One of the problems with CMYK printing is that it generally uses only black ink for printing grays (in a grayscale image), so sometimes you need to make the shadows and highlights richer by using two (or more) inks. One ink will be black and one will be another color that will serve to give it a bit more depth. You can't do that with gradient maps since they really just don't work the same way as duotone, i.e., they can't use special colors like metallics.

Remember that gradient maps deal with the whole image while duotone is really only the shades of gray. If it's pure white it will not be affected by the colors you use in duotone since printers don't print white and the white parts don't matter.

In short, duotone uses two (or more) inks to produce the image that you want. Even if it seems like glorified grayscale, it most certainly is not. Keep that in mind and don't cheat. Cheating now will reinforce cheating later, and you never want to cheat when dealing with professional printing. Do the work and it'll pay off with a slick image.

By the way, you do know how to work with duotone... right?

[jumbo]

It seems like you are saying duotones are an enhancement for grayscale images. What I am trying to do is make the best of my limitations.

Often times, graphic designers have to work with only two colors/inks. My instructor set that as a criteria for this project so we would face the design challenges it presents.

When I see this project with its two color limitation, I think about the hundreds of shades I can get from them, and that is why Photoshop's duotone process frustrates me when it just mixes the two colors into a muddy single color.

Here is an example of what I'm talking about. I've taken an old render of mine and applied the same two colors to it, using a gradient map, (top), and duotone, (bottom). The two Pantone colors are Pantone 2597 C, (purple), and Pantone 185 C, (red). (I put a square swatch of each on the image for more clarity).

Unfortunately the more dynamic gradient map doesn't preserve how much of what inks it should use in each spot, so duotone seems to be my only option.

Does anyone know of a way to get Photoshop to identify the Pantone inks in its channels or something?

[halo]

Does anyone know of a way to get Photoshop to identify the Pantone inks in its channels or something?

you aren't limited to duotones for pantone use, you can add pantones as spot channels, but you will need to save the files out as DCS 2.

When you use spot channels for pantones, they sit along side the cymk channels so leave them blank. You will also have work with the preview problems as PS doesn't display overprint on spot channels like duotones do...your limited in opacity, which doesnt reflect the print output unless you use knockouts. Remember when you do use knockouts to set your trapping if your sending to a sheetfed press.

Working in a restrictive colour set as you describe in PS can be a bitch. Look into the curves of duotones to avoid mixing colours. You may find that working with spot channels is beter under certain circumstances or even working with 2 monotone images and pulling them together in a layout application may be better.

The main problem with "specials" is that, unlike process cymk, pantones aren't printed the same way under all circumstances...you may need to trap certain colours when one colour is used and sometimes not, sometimes you may print one colour first sometimes not...and then there is the screen to think about for when they are blended.

Still learning about they're limitations and how to work with them is valuable lesson for print design...you'd be amazed how many people out there don't understand this stuff and consquently make pretty designs up in rgb and then expect someone to make them work in two colour...it often leads to increased costs or a failed design. Sometimes what is required isn't acheivable within the software and the file either needs fettling or rebuilding by an experienced printer specifically for his press. It's often forgotten today what the dissapearing art of prepress entails...not everything can work straight out of PS and quark :)

[jumbo]

Thank you, halo. That was exactly what I was looking for. http://cgtalk.com/images/smilies/thumbsup.gif It's a little weird because you work with channels more than the actual layer/layers, but it works and works well.

For an update, here is the same image with the two colors using the spot channels. I don't know how it will look when it prints, but so far it looks nice. In fact, it almost looks like it's full color. It's unfortunate that this is not one of the images that I am using for the project.

Do you know if Quark will accept it like this? That's the program we are using for the project, and, come to think of it, I need to get all my other stuff set with the two colors, too.

I have a graphics class next term on print and production methods, so I might have learned about the spot channels there anyway, but its good to know it now.

[halo]

Do you know if Quark will accept it like this? That's the program we are using for the project, and, come to think of it, I need to get all my other stuff set with the two colors, too.

yes, you need to export the file as DCS 2 file, which will make a composite preview and make a file for every channel used...you need to keep these together and open the preview file in quark as far as i remember.

[jumbo]

For some reason, when I try to print something from the document, it displays a warning message about some of the eps files containing binary. I usually ignore it when it displays a message like that, but tonight I tried to print the separations, the printer went psycho and started shooting out paper with one line or less of weird characters on most pages.

What's going on here?

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