spots on underside but it turned white when it sat on the concrete. good blend into surrondings. i have seen this type of frog arounhd shoalhaven heads before they have turned up sitting in the gas bbq and in pots etc
This is a Peron's Tree Frog - distinguishing features are the criss-cross pupil, tiny emerald green spots on the back (just discernible in the photo) and the black and white/yellow blotches in the groin. They're good at changing tone as you mention, tending to become paler at night and darker during the day, depending on the background.