Question about the principle of texture mapping

  1. i would like to ask what is texture scanning and pixel order scanning???
    based on my notes it said that texture scanning is map texture pattern in texture space to image space,
    pixel order scanning is map texture pattern in image space to texture space,
    how we will use these two method to map texture pattern??
  2. And I want to ask what is the advantages and disadvantages of this two method.
    THANK YOU!!!