A

Anonymous

Question

Converting duotone to CMYK for print

Forum|Forum|8 years ago
October 3, 2017
5 replies
4714 views

I have a full colour RGB image of an explosion of mulitple paint colours on a black background. I want to change the explosion of colours to our brand teal green colour, with the background C 0%, M 0%, Y 0%, B 100%.

I have converted the RGB image to greyscale and then to duotone. Then set up my two inks. A 100% black and a CMYK teal green colour.

The image will be professionally printed. To avoid any problems with the duotone I want to convert it to CMYK. But when I do this, the black background becomes C 91%, M 79%, Y 62%, B 97%.

This is way too much ink density.

I was hoping that the the black would simply stay C 0, M 0, Y 0, B 100%. i.e. overprint / knockout the teal green that is 'behind' it. Instead the two inks (the black and teal green) and combining, making the black unprintable.

1. Any idea how I convert the duotone to CMYK without the black ink density becoming unprintable?

2. Or how I change the colours in the explosion to our brand colour (without using a duotone) and the rgb background to a solid CMYK (100%K) black

Thank you

ps. I've tried converting the RGB image to greyscale and then importing it into InDesign and then changing the background colour to our brand teal green. This works, but it doesn't look at good as the duotone.

This topic has been closed for replies.

J

JJLAPIN

Participating Frequently

The Black in this file will print fine in all the mediums you listed.

c.pfaffenbichler

Community Expert

The image seems to show traces of previous editing:

A

Anonymous

I've just had a quick look. I think that is the only example of something odd. I bought the image from Adobe Stock, so I'd be upset if there were more issues with the image

T

Test Screen Name

Legend

If you don't know what CMYK profile you're using you have a problem. You need to use one designed for your press conditions. CMYK isn't a generic thing.

c.pfaffenbichler

Community Expert

Test Screen Name makes a valid point.

While the pure »green« might appear similar in several print processes (at least while one does not actually hold one product directly up against another) the different gains may affect the appearance of the image’s brightness differently and thus affect the overall impression.

A

Anonymous

Wow thank you for your help. This is well outside my comfort zone and I don't understand how to do your suggestions.

Could I simply create a CMYK file and two layers. The bottom layer would be solid teal green C100, M0, Y45 K40. I would then paste into the top layer the greyscale image. Then remove all the CMY from this layer (using Curves??).

Then set the blending mode for the top layer to be Multiply. Then flatten the image. The background colour is now (as expected) C100 M0 Y45 K100. A combined TIC of 245%. Considerably less than the previous 329% and therefore much more likely to print and dry okay?

A

Anonymous

Original full colour RGB image.

Duotone image

I need the black background to be C 0, M 0, Y 0, K 100%

And the explosion to be our brand green C 100%, M 0, Y 45%, K 40%

But when I convert from duotone to CMYK the black background ends up as C 91%, M 79%, Y 62%, B 97%

which no printer will want to print cos' there is too much ink.

c.pfaffenbichler

Community Expert

I asked for meaningful screenshots and the TAC seems unproblematic unless you have specific, conflicting information about the actual print process that you have not divulged.