Photoshop & Indesign - changing a colour

[Ally C 25]

Hi All, 

Not sure if i am in the right place, but bear with me. 

I have kind of been taught this by a previous manager, but I dont recall the steps, hoping someone here knows what I am referring to. 

I have a file in photoshop supplied, its like a honeycomb texture. I need to create a spot colour the same as this, that my printers will print as white ink. 

From what I recall, I have created a layer the same as the honeycomb shape. I have made it black. I should then be able to place the file in indesign, and selecting that layer only, change it to a spot colour (with the necessary attributes) that the printer will pick up. 

Can anyone help me? I havent found a tutorial for it, and chat gpt has told me its not possible - but i know it is. 

Thanks in advance, 

Ally. 

[Stephen Marsh · Accepted solution]

You will need to make a copy of the file and save it as a 1-bit TIFF in order to colour it in InDesign. First using Image > Mode > Grayscale, then Image > Mode > Bitmap, selecting 50% threshold. As this is now "lineart", what is the effective PPI resolution of the image when placed in InDesign at final print size?

[Ally C 25]

Is it possible to have them both in the same file i.e. the colour layer and the layer i need to change in indesign? or am i remembering incorrectly? 

[Stephen Marsh]

You need to use either duotone mode > monotone or spot colour channels if you wish to have a single file with a single spot colour populate into Illustration or Layout software.

[Ally C 25]

Ive been able to get it working 🙂 Thank you! 

[Stephen Marsh]

Ive been able to get it working 🙂 Thank you! 

By @Ally C 25

You're welcome! And what is the effective PPI resolution of the bitmap mode TIFF that you have coloured in InDesign?