Threading

I wanted to convert a large HD image to Black and White
with this small library:

http://www.b4x.com/forum/basic4andr...018-how-grayscale-color-bitmap.html#post67295

This seems to take more than 5 seconds, so I would like
to not clog up the UI, how would I do this in the threading
library, can someone point me in the right direction

thanks in advance