by steps
000000 000000
000000
7f7f7f 7f7f7f
7f7f7f
00007f 00007f
00007f
0000ff 0000ff
0000ff
007f00 007f00
007f00
007f7f 007f7f
007f7f
878888 878888
878888
007fff 007fff
007fff
00ff00 00ff00
00ff00
00ff7f 00ff7f
00ff7f
8f9191 8f9191
8f9191
00ffff 00ffff
00ffff
7f0000 7f0000
7f0000
7f007f 7f007f
7f007f
989a9a 989a9a
989a9a
7f00ff 7f00ff
7f00ff
7f7f00 7f7f00
7f7f00
a0a3a3 a0a3a3
a0a3a3
7f7fff 7f7fff
7f7fff
7fff00 7fff00
7fff00
7fff7f 7fff7f
7fff7f
7fffff 7fffff
7fffff
a8acac a8acac
a8acac
ff0000 ff0000
ff0000
ff007f ff007f
ff007f
ff00ff ff00ff
ff00ff
b1b5b5 b1b5b5
b1b5b5
ff7f00 ff7f00
ff7f00
ff7f7f ff7f7f
ff7f7f
ff7fff ff7fff
ff7fff
b9bebe b9bebe
b9bebe
ffff00 ffff00
ffff00
ffff7f ffff7f
ffff7f
ffffff ffffff
ffffff
c2c7c7 c2c7c7
c2c7c7