Spirit and the mars-wonder

As the german SPIEGEL reports in its online issue, the mars roboter „opportunity“ sent wonderful pictures to earth having a resolution of about 8000 x 3000 pixels. It is said, that details are from such high quality that you can see even sandkorns. Well, it was very interesting to know in which format the pictures are sent: How can you transfer such big pictures in such short time over millions of kilometres? It would be a very nice format for the internet, too 😉