Hide an image in a album (but still process it and allow it as a thumbnail)

[Dave]

I'd like to be able to hide an image in a album, but still have the image available as a resized thumbnail.

Use case

I'd like to create thumbnails for specific albums by cropping a high resolution image to focus/highlight a specific part of the image, but I don't want the thumbnail actually displayed in the album when viewed.

Example implementation:

index.md
thumbnail: mythumb.jpeg

mythumb.md
hidden: true

Alternatively, even a "hide_thumbnail: true" in index.md would be fine, although I can imagine cases where you might want to hide other images.

Thoughts

To simplify for the user, I would still like the thumbnail to be processed/resized as needed, for example, a user might crop a 4000x4000 image to 1000x750, but my thumbnails are (280, 210), the user shouldn't need to know the details of the theme and the theme might change in the future.