2d image mask support

[briancantwe]

Hello, and congratulations on your awesome work! Now that you've added Colmap support, I'm really excited to dive in.

Question, do you plan to support 2d image masks? These would be used to ignore specific regions of the image during training.

Thanks so much!

[pierotofy]

Hey, 👋 this would be a cool feature for sure; while my focus is going to be on other priorities in the short term, we'd welcome a PR that adds support for image masks!