Split shaders by color?

[yaschancool]

Is it possible to somehow separate shaders by color value? For example if I have a model textured with red paint.
Would it be possible to create a shader that automatically masks out red areas and assigns a car paint shader for the red areas?

Maybe using color tint or something, but does that work with UDIMs?

Having ten million UDIMs, creating the mask manually is going to be a challenge.

[hermit.crab]

Not sure if there is a direct approach, however, it is possible with texture baking and extracting the red as a mask. Try the following setup. Bake a VRayDiffuseFilter for your model through Render to Texture/Bake to Texture, load it as an input image to a 'Color Key' node, set the key color (to red in your case), and extract the Key result (this will be the mask). Use the result to mask the VRayCarPaintMtl in a VRayBlendMtl.