It is a sample code for

1. loading masks
2. generating an overlay between an original image and a mask
3. resizing to make an image fit into simple viewers (e.g. Windows default viewer, Fiji, etc.)

Please note that this code is not providing svs loading part because there are several well-known open source library for this. (e.g. openslide, pyvips, etc.)

It is another extremely simple code for

1. loading a mask
2. saving after applying ADOBE_DEFLATE level 9 compression with the same filename (may overwrite)
3. the output will have around ten times smaller file size compared to the original uncompressed tif