You execute the first loop twice with $x set to 0 and 1. You build entries 0 and 1 in @para1 and @para2. When you leave the first loop, $x = 2. You then attempt to execute the second loop with $x set to 2 but you never defined that entry in the arrays. Move the decrement to the beginning of the loop.

while ($x >= 0){
    $x--;
    $image->filledPolygon($para1[$x], $black);
    $image->filledPolygon($para2[$x], $yellow);
}
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print map { my ($m)=1<<hex($_)&11?' ':'';
$m.=substr('AHJPacehklnorstu',hex($_),1) }
split //,'2fde0abe76c36c914586c';
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