2-bit   3-bit   8-bit      hex   dec
00      000     00000000   00      0
        001     00100100   24     36
        010     01001001   49     73
01      011     01101101   6D    109
        100     10010010   92    146
10      101     10110110   B6    182
        110     11011011   DB    219
11      111     11111111   FF    255

ULAplus colours are stored as 8-bit big-endian GRB values.

The green and red channels are encoded in 3-bits, while the blue channel is
encoded in 2-bits (multiplexed to 3-bits by using the logical OR of the bits to
determine the least significant bit).

The 8-bit value for a channel is determined by repeating the 3-bit value and
discarding the 9th (least significant) bit.