Expose css image filtering options to UI

[njwitthoeft]

Modern browsers seem to hardware-accelerate basic image filtering via css.

This chrome extension is being used, but it makes me sad, because it modifies the whole screen and makes text contrast poor.

It would nice to expose a pop-up or collapsing menu to allow users to apply basic css filter properties, like brightness, contrast, hue-rotate, invert, and saturate. Each of these values accepts a continuous value and could be exposed via a slider.