Unintuitive read_region for levels

[jxu]

Context

Issue type (bug report or feature request): Feature request
Operating system (e.g. Fedora 24, Mac OS 10.11, Windows 10): RHEL 7.6
Platform (e.g. 64-bit x86, 32-bit ARM): x86_64
OpenSlide Python version (openslide.__version__): 1.1.1
OpenSlide version (openslide.__library_version__): 3.4.1
Slide format (e.g. SVS, NDPI, MRXS): SVS

Details

For read_region in non-0 level I've found out that location is relative to level 0 image (stated in docs) but size is relative to level image. The docs say

Unlike in the C interface, the image data is not premultiplied.

but this should be clarified.

[VincePlantItAi]

has anyone provided a solution for this? it's quite unintuitive.
If the admins/managers of openslide-python allow me and give simple example to make things clear,
I could totally fix it (python-side only) myself.

def read_region(<originalparams>):
# do some simple location and size calcuation here before passing to openslide lib
return user_desired_image

[bgilbert]

Premultiplied refers to the pixel data, not the boundaries of the region. We match the OpenSlide API here: location is in level 0 and size is the actual size of the region we're reading.

[VincePlantItAi]

thank you @bgilbert for your reply.

So the main point behind your response is, the original openslide API should be matched, so we cannot change the python wrapper for OpenSlide into its own.

Did I get you correctly?