Open up your picture and a blank image 800×600 in Photofiltre.
Copy the picture of Miley and go to the blank image. Press Ctrl-V to paste it.
Press Ctrl-V to paste it again and move it like mine:
Go to Edit >> Fade Paste >> 80%.
Go to Edit >> Define Pattern.
Go to Filter >> Stylize >> Mosaic >> 25.
Go to Edit >> Fade Mosaic >> 50%.
Using the Clone Stamp tool erase the parts of the mosaic on top of Miley’s face and where ever you want on the left half of the picture.