Masking colours with material nodes

[Miles_Rat (Miles)]

Hi! I’m trying to mask out some colours for a PCB render. I have several pngs converted from vector drawings for layers like soldermask, pads and copper traces.

What I’m looking to do in this particular case is mask out the purple and only use the blue as a metalness mask. I can only use both as metalness but this doesn’t give the intended result.

Is there any way of telling Blender to hide the purple and then convert the blue to white for metalness? There’s also white outlines which appear that I’d like to mask out. Is it just easier to delete all the parts I don’t want in the original drawing at this point?

Thanks!
Miles

(Extra screenshots had to be removed because I’m new)

[Lumpengnom]

If it is pure blue you can use a separate rgb node and use the blue channel.

If not you will have to plug the blue channel into a color ramp which you need to set to “constant” and fiddle with it a bit:

[Miles_Rat (Miles)]

Thanks for this! This was pretty much the best thing I could do! seperating the rgb based on what I needed to mask out, sometimes boosting that colour with a math node and then using the outcome as a factor. I’ll include a screenshot.