Trouble using freeimage plugin on MacOS arm64

[aknoerig]

I just ran into a number of strange issues with the freeimage plugin and am wondering if it's just me. :)

Side note: Initially, I had trouble using imageio.plugins.freeimage.download() causing SSL certificate errors, so I used the command line alternative imageio_download_bin freeimage.

Running something as simple as:

import imageio
img = iio.imread('imageio:chelsea.png', format='PNG-FI')

results in the error: OSError: PNG-FI can not handle the given uri.

From the traceback, it seems to be related to how LegacyPlugin handles the Request

self = <imageio.core.legacy_plugin_wrapper.LegacyPlugin object at 0x106069390>
request = <imageio.core.request.Request object at 0x106068af0>
legacy_plugin = <Format PNG-FI - Portable Network Graphics>
...
        if not self._format.can_read(request):
>         raise InitializationError(f"`{self._format.name}`" f" can not read `{source}`.")
E     imageio.core.request.InitializationError: `PNG-FI` can not read `imageio:chelsea.png`

I tested on a Ubuntu system, too, and there it's working as expected.

My setup:

• imageio v2.33.0
• installed via conda environment
• MacOS 14.1.1
• MacBook with M2 chip (arm64)

[aknoerig]

Upon further digging, it does seem to be caused by the fact that the freeimage library can't be loaded properly.

Unfortunately, there is no error logged that indicates this:

• _format.can_read returns False if the freeimage library can't be loaded, but it just prints the above error message
• iio.plugins.freeimage.download() doesn't throw any errors, just returns None
• imageio.plugins._freeimage.get_freeimage_lib() doesn't throw any errors, just returns the path the library was downloaded too
• imageio.plugins._freeimage.fi.load_freeimage() finally returns a message that the library can't be loaded

If this is validated by other users, I'd suggest to include an appropriate error message for the above functions.

[aknoerig]

Ah, I just discovered the related discussions in #628, which has more about how to fix the arm64 support.

Leaving this here to suggest an update to the documentation and possibly an enhanced error message.