@ajsc4 As a follow up, the first version of my package TiffImages.jl is out on the general registry. It supports opening most common TIFF types (including BigTIFFs, HDR formats, etc) and can load them out-of-memory so it should do what you need. I’m actively working on making it more versatile.
Here’s a link to the documentation about how to read/write TIFFs: Home · TiffImages.jl
It’s a super fresh package so please open issues on the github page if you run into any limitations. I test it thoroughly on many different TIFF types, but it’s not called Thousands of Incompatible File Formats without reason 