Recently, I found that I can invert all the colours on my apple laptop via the system preferences*.
It was a fascinating experience for me to go over familiar work of mine and notice new things in the work. All because I was being forced to see it differently through inverting the colour and luminosity.
What was most fascinating for me, was how my perception changed about the work. With some images I was able to see new shapes that had not been apparent upon previous viewings. Other times it was more that I noticed imbalances in the tones between one area of the image to another area. But I also found that sometimes the images just became quite erie in some way. A new mood or feeling was being projected by them.
As a photographer, I'm always looking for ways to see my images anew. The problem with working on images for so long or living with them for a while, is that become invisible. I stop seeing what's really there, and I become blind to potential errors or issues in the work.
Inversion has been a technique used for a long while. When composing, or editing my work, I will sometimes turn the image 180º so that my eye is forced to walk around the image in a different way. Since I am mostly a left-to-right viewer, I find my eye stumbles into things that weren't an obstruction when they were turned the right way up.
So if you can use rotation to invert an image and see it differently, then why not invert it tonally?
* To invert the colours or turn your entire screen monochrome, go to System preferences / Accessibility and choose the Display submenu, you will see the choices 'invert colours' and also 'use grayscale'.