This is an episode of room transformation video, and this may be the cheapest and most immediate way to improve projection image quality.

Disclaimer: For those with a living room at home, please be prepared for some scolding before you start the operation...

Darkening material: Non-woven velvet fabric

Friendly reminder: If you're planning to do this too, it's best to buy enough materials at once, as there can be differences in brightness between different batches.