If you are looking for a lightweight image effect or something minimal but effective for decorating your game or project, here is Effects Pro - Simple Image Effects.

This tool can be useful for adjusting contrast and brightness. Also it can provide real time image effects or camera effects. Now this asset contains three image effects. More image effects will be added to this asset in future updates. So why not give a try. The image effects are

Greyscale

Sepia

Negative

This package is also lightweight. Even you can adjust the style strength for those applied effects. Just simply add the Effects.cs to your camera and give a boost to your development workflow.