Add an option to invert colours

[dan1elhughes]

👋 Love this project - thank you for making this!

Describe the problem

My Waveshare appears to be a bit bugged, and presents all images inverted. It might be that I've got the connector upside down, but it only shows anything that way round.

Describe the solution you'd like

An option to invert the presented image.

Describe alternatives you've considered

Inverting the MP4 before uploading somehow 🤔

[dan1elhughes]

oh god.. I was looking at the back. 🤦‍♂️