Windows 10 Login Screen Background Changer! Updated Script

$priPath = "$env:windir\SystemResources\Windows.UI.Logon\Windows.UI.Logon.pri"
$outputPath = ".\Windows.UI.Logon_new.pri"
$replacementPath = "C:\Windows\Web\Wallpaper\Theme1\img1.jpg"

try
{
    $inputStream = [System.IO.File]::OpenRead($priPath)
    $outputStream = [System.IO.File]::Create($outputPath)
    $replacementStream = [System.IO.File]::OpenRead($replacementPath)

    $inputReader = New-Object System.IO.BinaryReader $inputStream
    $outputWriter = New-Object System.IO.BinaryWriter $outputStream

    $inputStream.CopyTo($outputStream)

    $replacementLengthAligned = ([Math]::Ceiling($replacementStream.Length / 8) * 8)

    # header
    $inputStream.Seek(0x14, "Begin") | Out-Null
    $headerLength = $inputReader.ReadUInt32()
    $inputStream.Seek(0xB8, "Begin") | Out-Null
    $dataitemOffset = $inputReader.ReadUInt32()
    $origDataitemLength = $inputReader.ReadUInt32()
    $dataitemLength = $origDataitemLength + $replacementLengthAligned
    $outputStream.Seek(0xBC, "Begin") | Out-Null
    $outputWriter.Write([int]$dataitemLength)

    # dataitem
    $outputStream.Seek($headerLength + $dataitemOffset + 0x18, "Begin") | Out-Null
    $outputWriter.Write([int]$dataitemLength)
    $inputStream.Seek($headerLength + $dataitemOffset + 0x24, "Begin") | Out-Null
    $stringCount = $inputReader.ReadUInt16()
    $blobCount = $inputReader.ReadUInt16()
    $origDataLength = $inputReader.ReadUInt32()
    $outputStream.Seek(0xC, "Current") | Out-Null
    $outputWriter.Write([int]($origDataLength + $replacementLengthAligned))
    $outputStream.Seek($stringCount * 4, "Current") | Out-Null
    $blobTableOffset = $outputStream.Position
    $dataOffset = $blobTableOffset + $blobCount * 8
    $wallpaperBlobs = @()
    for ($i = 0; $i -lt $blobCount; $i++)
    {
        $inputStream.Seek($blobTableOffset + $i * 8, "Begin") | Out-Null
        $offset = $inputReader.ReadUInt32()
        $length = $inputReader.ReadUInt32()
        $inputStream.Seek($dataOffset + $offset, "Begin") | Out-Null
        if ($inputReader.ReadUInt16() -eq 0xD8FF)
        {
            $wallpaperBlobs += $i
        }
    }
    if ($wallpaperBlobs.Count -ne 10)
    {
        Write-Error "Not compatible with this PRI file."
    }
    foreach ($id in $wallpaperBlobs)
    {
        $outputStream.Seek($blobTableOffset + $id * 8, "Begin") | Out-Null
        $outputWriter.Write($origDataLength)
        $outputWriter.Write([int]$replacementStream.Length)
    }

    # data
    $outputStream.Seek($dataOffset + $origDataLength, "Begin") | Out-Null
    if ($outputStream.Length - $outputStream.Position -ne 0x18)
    {
        Write-Error "Not compatible with this PRI file."
    }
    $replacementStream.CopyTo($outputStream)

    # footer
    $outputStream.Seek($replacementLengthAligned - $replacementStream.Length, "Current") | Out-Null
    $outputWriter.Write(0xDEF5FADE)
    $outputWriter.Write([int]$dataitemLength)
    $outputWriter.Write(0xDEFFFADE)
    $outputWriter.Write(0x00000000)
    $outputWriter.Write([char[]]"mrm_pri2")

    $outputStream.Seek(0xC, "Begin") | Out-Null
    $outputWriter.Write([int]$outputStream.Length)
    $outputStream.Seek(-0xC, "End") | Out-Null
    $outputWriter.Write([int]$outputStream.Length)
}
finally
{
    if ($inputReader -ne $null)
    {
        $inputReader.Close()
    }
    if ($outputWriter -ne $null)
    {
        $outputWriter.Close()
    }
    if ($replacementStream -ne $null)
    {
        $replacementStream.Close()
    }
}