Is there a way to filter/exclude some images from being imported?

My art department likes to deliver me a full complement of textures, some of which are sources for other things, but they should not be imported to Unity (they are large, take forever, and contribute zero to the project). But we want to somehow keep them together for source management. An example might be 4 grayscale images which get 'packed' into a 4 channel texture, and shaders use each channel for different things. We import the 4 channel file, but not the others, if possible.

Is there a way to exclude them from being imported, while keeping them somewhere under Assets and not under StreamingAssets? Like, if we used a naming convention (by file or folder), or some kinda meta file. The idea being to first look for that name or file, and decide whether to allow the import to happen. And, then allow Unity to do its default thing (not write our own texture importer).

Any ideas on how we might accomplish this?

 

Why yes, please see the 'hidden assets' part of this page: https://docs.unity3d.com/Manual/SpecialFolders.html