My call would beUpdate (origianlly said to change all the instances of 256 to 512 except the last which definespng definition)
Taking a look at your update and the image type. My reading is thatcode a bit more carefully, you were right originally - if you also leave the first 256 is used to map the pixelsc = 256
in the imageGoogelProjection
initialisation you will get the tiles back at the correct resolution. However your tile naming convention will be changed compared to the projection256 tiles, so it needs towhich depending on your application may or may not be upped as wellimportant (x and y are halved). Good luck!