Hello nusaki,
There is simple step around using PixelGetColor(). However, it will lose the ability to use shade-variations for searching. If you need the shade-varietions. then try defining 4 seperate PixelSearch() controls searching 0,0,100,9 and 0,10,9,20 and 21,10,100,20 and 0,21,100,100.
However there is another more simple way if you need to find a specific pixel color using loops:
For $row = 0 To 100
For $col = 0 To 100
If $row >= 10 And $row <= 20 And $col >= 10 And $col <= 20 Then ContinueLoop
$search = PixelGetColor( $row, $col )
If $search = $color_to_find Then
;do something here
EndIf
Next
Next