892370.fig.002a
(a) 𝜑 ( 𝑛 , 𝑎 ) = 0
892370.fig.002b
(b) 𝜑 ( 𝑛 , 𝑎 ) = 1
892370.fig.002c
(c) 𝜑 ( 𝑛 , 𝑎 ) = 2
Figure 2: The figure gives the different combinations of pixels available for each category. The pixels are designed as follows : black pixel ( C D M ( 𝑛 , 𝑝 ) = 0 ) , gray pixel ( C D M ( 𝑛 , 𝑝 ) = 1 ) , white pixel ( C D M ( 𝑛 , 𝑝 ) = 2 ) .