The imagery team just posted a blog on the LERC technology we released today for making it fast, accurate and easy to share imagery and raster data over the web.
The new approach to data compression enables you to set a tolerance for how much the compressed values can change from the original values. We call the algorithm that does this LERC (Limited Error Raster Compression). Using LERC, you can set a tolerance of 10 cm when you compress the data, and the result is a dataset that is compressed as much as possible while remaining true to that 10cm tolerance that you set. You can also set the tolerance to 0 which makes the compression lossless. In most cases LERC provides better lossless compression than traditional lossless compression methods such as LZW and deflate.