8

I've been asked to design a poster that will be printed in two inks: black and pantone 631c. It's a simple design, a photograph and text. Should the photo be in grayscale mode + duotone in monocrome (black only) or should it be in duotone black + pantone 631c? or is it up to me and i can just choose whatever? thanks

10

Do whatever you want. But do something interesting.

Starting from a single gray image

A normal duotone is made of a single grayscale image (A) used by two inks (B, C).

enter image description here

You can adjust the curves on one ink to modify the amount of the final ink on that plate. In this case (D), I am lowering the blue ink on the face and adding more on the dark areas. The Z image is a comparison without doing this adjustment.

enter image description here

One typical usage is doing a "sepia look"; the darker zones are exaggerated to add black to the overall sepia tone.

enter image description here

Starting from a color RGB image; Complementary color

But more possibilities arise from using a full-color image to extract the grayscale images from different channels for different plates.

In this case, we want to pop the red of the sweater.

enter image description here

But if we simply convert the image to one grayscale, we will fail regardless of the curves adjustments.

enter image description here

Lets now see the channels of the original image. Which one do you think will work best to print red?

enter image description here

The answer is the green channel. Why? Because an intense red, has little or no green at all, therefore that part is black in the green channel.

The blue channel could work too, but as we want intense red, let's use the more intense black.

enter image description here

Now, that is better, the red is starting to pop. Look how we used the complementary color we needed. We needed red, so we used the green channel.

enter image description here

But nothing is telling us that we should use black ink. If we use now the red channel for some green ink, things are better now.

enter image description here

Sometimes we do need a CMYK Channel

Sometimes, we actually need to use a CMYK channel.

In this image, neither of the RGB channels have good information about the pink zone. So I need to use the M channel. (Some tweaking of the color profile might be needed, but I will try to write about it in another time)

enter image description here

Some curves here, and some contrast there and voilá!

enter image description here

Do not be limited on the original image, saturate it, mask it, use different colors as the original ones... Have fun.

enter image description here

Another related answer: Printing photographs when job is a 2 spot color job

Original images:

https://pixabay.com/es/chica-moda-belleza-modelo-ruso-1848958/

https://pixabay.com/es/bailarina-pared-zapatos-de-pointe-1828541/

https://pixabay.com/es/chica-maquillaje-ruso-modelo-1848455/

https://pixabay.com/es/azul-mezclilla-chaqueta-2564660/


Here is the old version of the post

Do whatever you want. But do something interesting.

A normal duotone is made of a grayscale image (A) and then converted into a duotone (B)

If you edit the curves on one ink, for example, you can have something a bit different (C)

enter image description here

But you can take a more interesting approach.

  • Convert the image to grayscale for the black ink (D) Play with the contrast.

  • But for the 631 ink use the complementary RGB channel, in this case, Red (E) Play with the contrast.

  • Make the 631 to a monotone and assign your Pantone color and put it on top of the other.

  • To preview it use multiply (F). Now that is a cool duotone!

enter image description here

You can mask the sky, mask the skin so no blue color cast on the face, etc.

Note

In some cases, you need to use some of the CMYK channels but start with the complementary RGB. The reason for this is that CMYK channels can decrease the amount of ink when the color is approaching a very dark black.

(I love some results a duotone can achieve) :o)

Original Photo: https://pixabay.com/static/uploads/photo/2016/08/05/14/53/girl-1572419_960_720.jpg

  • Follow-up question on this answer. – Wrzlprmft Oct 19 '18 at 17:51
  • Good clarification. I'm still a tad unsettled by using the term "duotone" and working on an RGB image -- that is really an impossibility - there's no such thing as a 2 "plate" RGB image, but okay. – Scott Oct 20 '18 at 2:40
  • I added: Using a full-color image to extract the grayscale images from different channels for different plates. – Rafael Oct 20 '18 at 6:21

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.