The present disclosure relates generally to signal encoding for containers such as shipping boxes, food containers, wrapped items such as pallets. One aspect of the technology relates to an image processing method for determining spatial dimensions of an encoded surface. The method comprises: obtaining an image depicting the encoded surface, in which the encoded surface comprises one or more raw data signal tiles printed thereon, with each tile comprising a side length N in inches or centimeters; detecting each of the one or more raw data signal tiles from the obtained image; determining a total number of tiles in a vertical direction, and determining a total number of tiles in a horizontal direction; determining a height and length of the encoded surface by multiplying each of the total number of tiles in a vertical direction and the total number of tiles in a horizontal direction by the side length N. Other aspects are described as well.