Something interesting about the San Francisco test image is that if you start to look into the details, its clear that some real changes have been made to the city. Rather than losing texture or grain or clarity, the information lost in this is information about the particular layout of a neighborhood of streets, which has now been replaced as if some one were drawing the scene from memory. A very different kind of loss that with out the original might be imperceptible because the information that was lost isn't replaced with random or systematic noise, but rather new, structured information..