PowerShell script to prefix files by Date Taken from EXIF data

Rename-ItemsByDateTaken.ps1

function Get-DateTakenFromExifData {
  param([String] $filePath)

  try { 
    $imgData = New-Object System.Drawing.Bitmap($filePath)
    try {
      [byte[]]$dateTakenExifData = $imgData.GetPropertyItem(36867).Value
      [string]$dateString = [System.Text.Encoding]::ASCII.GetString($dateTakenExifData)
      return [datetime]::ParseExact($dateString, "yyyy:MM:dd HH:mm:ss`0", $null) 
    }
    finally {
      $imgData.Dispose()
    }
  }
  catch { }

  return $null
}

function Get-DateTimeForFilePrefix {
  param([System.IO.FileInfo] $fileInfo)

  $date = Get-DateTakenFromExifData ($fileInfo.FullPath)
  if ($date) {
    return $date
  }
  else {
    return $fileInfo.LastWriteTime
  }
}

Get-ChildItem | ForEach-Object {
  $from = $_.Name
  $dateTimeForPrefix = Get-DateTimeForFilePrefix $_
  $to = "$($dateTimeForPrefix.ToString('yyyyMMdd_HHmmss')) $from"
  Write-Host "Renaming `"$from`" to `"$to`""
  Rename-Item $from $to
}