Welcome!
With κ tiles selected, the image you provide will be reduced to κ colors, and each color will be assigned to one of the selected tiles.
Landfill tiles appear transparent in the preview. You can make silhouettes from 2-color images by selecting 2 tile types, or from 1-color images with PNG alpha channel.
Higher κ yields more detail. You can select and re-order the tiles in the list below to tune the aesthetics of the resulting blueprint. Have fun!