Info about each of the options:

Normalize - This will round each RGB value to the nearest N value specified (eg 57, 123, 245 rounded to nearest 50 will result in 50, 100, 250).
This slightly alters each color present, but allows the algorithm to have a smaller selection of colors to choose from. Range is 0 - 255. Default is 50 and off.

Soften - This will go through pixel by pixel and round each pixel to the average of its neighbors.
This results in a slightly blurred image with the goal of allowing the algorithm to again have a smaller selection of colors to choose from. Default is off.

Clean - A quick algorithm that goes through and removes any insignificant areas of color (ie color areas that are smaller than 4 pixels).
Default is on.

Sim Distance - AKA Similarity Distance is the value used to determine whether two colors are similar. The lower the number the more similar colors must be as determined by their CIELAB color.
Lower this number if you want more colors, raise it if you want want fewer. Range is 0 - 100. Default is 28.0.

Color Count - The maximum number of colors that you'd like to paint with.
Default is 25.

Outline Darkness - Lower this number for lighter lines, raise for darker lines and numbers. Range is 0 - 255.
Default is 64.

Resize First - This will resize the image to it's final size before calculations (Final size is scaled to fit a 720px x 960px pdf document).
On means a faster calculation, but less detailed result. Default is on.

Debug Info - Slightly misleading as this doesn't really provide any true debug info. If on, it will return all the different stages instead of just the original, and final result (eg it will also return the Normalized image if on).
Default is off.