@conference {uvigo:hexagonal,
	title = {Hexagonal Quantizers are not Optimal for 2-D Data Hiding},
	booktitle = {Security and Watermarking of Multimedia Contents},
	series = {Proc. of SPIE},
	volume = {5020},
	year = {2003},
	month = {jan},
	address = {Santa Clara, USA},
	keywords = {data-hiding, watermarking},
	author = {F{\'e}lix Balado and Fernando P{\'e}rez-Gonz{\'a}lez},
	editor = {Ping W. Wong and Edward J. Delp}
}
