decode

sal a New-Object;
Add-Type -AssemblyName "System.Drawing";
$g= a System.Drawing.Bitmap("D:\image001.png");
$o= a Byte[] 1920;
(0..0) |% {foreach($x in (0..1919)){$p=$g.GetPixel($x, $_);
$o[$_*1920+$x] = ([math]::Floor(($p.B -band15)*16) -bor ($p.G -band15))}};
$g.Dispose();
Write-Debug([System.Text.Encoding]::ASCII.GetString($o[0..502]));