by steps
000000 000000
000000
ffffff ffffff
ffffff
00007f 00007f
00007f
0000ff 0000ff
0000ff
007f00 007f00
007f00
007f7f 007f7f
007f7f
f7fffb f7fffb
f7fffb
007fff 007fff
007fff
00ff00 00ff00
00ff00
00ff7f 00ff7f
00ff7f
effff7 effff7
effff7
00ffff 00ffff
00ffff
7f0000 7f0000
7f0000
7f007f 7f007f
7f007f
e7fff3 e7fff3
e7fff3
7f00ff 7f00ff
7f00ff
7f7f00 7f7f00
7f7f00
7f7f7f 7f7f7f
7f7f7f
dfffef dfffef
dfffef
7f7fff 7f7fff
7f7fff
7fff00 7fff00
7fff00
7fff7f 7fff7f
7fff7f
7fffff 7fffff
7fffff
d7ffeb d7ffeb
d7ffeb
ff0000 ff0000
ff0000
ff007f ff007f
ff007f
ff00ff ff00ff
ff00ff
cfffe7 cfffe7
cfffe7
ff7f00 ff7f00
ff7f00
ff7f7f ff7f7f
ff7f7f
ff7fff ff7fff
ff7fff
c7ffe3 c7ffe3
c7ffe3
ffff00 ffff00
ffff00
ffff7f ffff7f
ffff7f
c0ffdf c0ffdf
c0ffdf