Yes, pyvips usually includes openslide, so you can't use both together.
Use .get_fields()
to see all the metadata on an image, for example:
$ python3
Python 3.9.7 (default, Sep 10 2021, 14:59:43)
[GCC 11.2.0] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>> import pyvips
>>> x = pyvips.Image.new_from_file("openslide/CMU-1.svs")
>>> x.width
46000
>>> x.height
32914
>>> x.get_fields()
['width', 'height', 'bands', 'format', 'coding', 'interpretation', 'xoffset', 'yoffset',
'xres', 'yres', 'filename', 'vips-loader', 'slide-level', 'aperio.AppMag', 'aperio.Date',
'aperio.Filename', 'aperio.Filtered', 'aperio.Focus Offset', 'aperio.ICC Profile',
'aperio.ImageID', 'aperio.Left', 'aperio.LineAreaXOffset', 'aperio.LineAreaYOffset',
...
pyvips will open base level of the image by default (the largest), use level=
to pick other levels, perhaps:
>>> x = pyvips.Image.new_from_file("openslide/CMU-1.svs", level=2)
>>> x.width
2875
See the docs for details:
https://www.libvips.org/API/current/VipsForeignSave.html#vips-openslideload