Some interesting features in this hi res jpg image

Just down from the top right of the image there are four or five domes, two of which appear to be almost perfectly circular and very smooth. There doesn't seem to be any central vent or crater, but they have a skirt or ridge a ways out from the base for part of the perimeter. I estimate they are about 1-2 km in diameter (the total image is 54.5 x 22.2 km)

Are these some kind of pressure dome? Eroded remnants of highland terrain?

There is a distinct "island" of highland area in the lower part of the image, but it looks as if there are some similar domes on top of this highland plateau.