[Feature] sliders for filters

[test2a]

Hi. The new filters are nice but the b/w is unusable if there is any shade on paper. I should be able to adjust levels using a slider. Same for magic color. Its right now all or nothing. Adjustable would be so much better

[VesperLlama]

It would be great if we can get sliders for brightness, contrast, saturation, etc and if possible ability to make our own presets.

[Iey4iej3]

Is it possible now to force the black and white mode? Open Note Scanner seems to support this.