Neumes in Generated Background Images Appear Different to Different Users

It appears that the output of the Fast Pixelwise Analysis has some issues with the background layer output file.

This is what the image is supposed to look like:

and that is the case with certain images we've used to test text_alignment. However, certain other images have white or black neumes depending on the user examining them. This may be an issue with the OS version or theme (Dark/Light).
Here is an example:


vs.


The problem is, images that appear black to certain users will NOT work with text_alignment. This is not an issue of simply not being able to see the image the right way. The images in these pictures are the same on a binary level via `diff`.