How to render separate monochrome layers? I have this logo:


.blend file: https://www.dropbox.com/s/1bib5ds8oufc9s9/logo.blend

The thing is I'm trying to make it lasercut. My lasercutter supports two colours - that is black and white (monochrome).
So, with the above logo I made it monochrome in Photoshop:


As you can see, no matter how I try, the logo will not actually work (the text is not readable)

But, this can be repaired by rendering each part of the logo black or white. For example, the background splodge could be in places white, and where there are the holes, black.

Then each of the circles could have an outline of black and the text could appear white, but to create the tilt effect, the sides of the text could be in black.

As you can see, I am trying to make the text visible by making certain parts black and some white. I could change the material colours in Blender, or something, but then it will do a gradient, which is the issue.

Thank you for reading my essay! ;) And I look forward to hearing from answers
Actually, monochrome effect can be easily done by ColorRamp node:



To your question:

As you mentioned, it seems that the only problem now is the tilt/side area on the text. I suggest to consider taking the advantage of Material Index here:



To do so:


First, convert the Text objects to mesh (Shortcut is AltC. You may want to remove doubles and correct normal directions after that);
Select all sided faces, then assign a new material to the selection (even can be the exact duplication as the original one, if necessary);
Set a different Pass Index value in setting of this material;
Toggle Material Index passes in Render Layer setting for outputting. You can then use it to separate the tilt/side area and have it controlled separately.




If you don't want to do it for compositing use, using plain materials with Shadelss toggled can also be an easier way:





UPDATE:

Inspired by gandalf3's cool answer, here is the option for outlined result, also with more control by ColorRamp.



You may also consider to generate outlines by FreeStyle, though relatively inefficient and less flexible in this case.