A photo of DVD movies in a display case served as the basis for this Liquib example.  The Mosaic Tool was applied with Tile Shape set to Rectangular and Averaged Colors/Shadows as the Tile Content, which fills each tile with a solid color calculated to be the average of the image pixels within the tile, mixed with a vague impression of the image itself.  Tile Size was set to 18 and Shape Regularity % to just 11%, which makes it possible for the tile shapes to be distorted as needed to align with detected image edges.  It can be very helpful to use the Adjust function after a Tool or Effect has been rendered to experiment with changing parameter combinations until the most satisfactory results are achieved.  The Image Manipulation History screen (the Hist button) provides even greater potential for altering rendered Tool and Effects.
Liquib Mosaic