The roasting process pre-stresses the wood, changing the cellular structure of the wood, sealing the pores and rendering them more resistant to moisture and movement. The caramelizing color pervades throughout the board thus enhancing the figure.
Boards have been wiped with a damp rag to reflect wood with a finish. Roasted color permeates throughout the wood.
Here is an example of a light golden and dark roasted curly maple, with and without water applied: