%!
54 112 translate % Locate lower-left corner of square
20 20 scale % Scale 1 unit to 120 points
0 0 moveto 0 1 lineto % Fill square with gray background
1 1 lineto 1 0 lineto closepath
..9 setgray fill
0 setgray % Paint mask black
24 23 % Dimensions of source mask
true % Paint the 1 bits
[24 0 0 -23 0 23] % Map unit square to mask

{<003B00 002700 002480 0E4940 114920 14B220 3CB650 75FE88 17FF8C 175F14
1C07E2 3803C4 703182 F8EDFC B2BBC2 BB6F84 31BFC2 18EA3C 0E3E00 07FC00
03F800 1E1800 1FF800>} % Mask data
imagemask
showpage
.