I want to share my tiff reader and writer, maybe someone finds it useful. It supports only a subset of the tiff format (like most). It is native, but uses openg's zip and g-image for jpeg compression.
I tested in in my use cases, but there will still be bugs and unsupported features. Please post issues at github.
If your are interested, visit https://github.com/kleinsimon/LV-Tiff