by steps
000000 000000
000000
ffff7f ffff7f
ffff7f
00007f 00007f
00007f
0000ff 0000ff
0000ff
007f00 007f00
007f00
007f7f 007f7f
007f7f
fbff7e fbff7e
fbff7e
007fff 007fff
007fff
00ff00 00ff00
00ff00
00ff7f 00ff7f
00ff7f
f7ff7e f7ff7e
f7ff7e
00ffff 00ffff
00ffff
7f0000 7f0000
7f0000
7f007f 7f007f
7f007f
f3ff7e f3ff7e
f3ff7e
7f00ff 7f00ff
7f00ff
7f7f00 7f7f00
7f7f00
7f7f7f 7f7f7f
7f7f7f
efff7e efff7e
efff7e
7f7fff 7f7fff
7f7fff
7fff00 7fff00
7fff00
7fff7f 7fff7f
7fff7f
7fffff 7fffff
7fffff
ebff7e ebff7e
ebff7e
ff0000 ff0000
ff0000
ff007f ff007f
ff007f
ff00ff ff00ff
ff00ff
e7ff7e e7ff7e
e7ff7e
ff7f00 ff7f00
ff7f00
ff7f7f ff7f7f
ff7f7f
ff7fff ff7fff
ff7fff
e3ff7e e3ff7e
e3ff7e
ffff00 ffff00
ffff00
ffffff ffffff
ffffff
dfff7e dfff7e
dfff7e