Tapping the menu icon on the lower right of the layer menu (1) will bring you to “Filters” (2).

Filter List

A list showing hue, Gaussian blur, mosaic, monochrome, line extraction, and reverse colors will be displayed.

Hue Saturation Brightness

This will allow you to adjust the hue/saturation/brightness of the layer you have selected.

Gaussian Blur

This will blur the layer you have selected.

Mosaic

This will add a mosaic to the layer you have selected.

Monochrome

This will turn the layer you have selected monochrome.

Line art extraction

This will extract the line from the image of the layer you have selected.

Conveat layer

This will convert the layer you have selected to a color layer, 8bit layer, or 1bit layer.