Change Sitecore Media Items Template Type using Powershell Without loosing Data.

$master = [Sitecore.Configuration.Factory]::GetDatabase("master");

$entryTemplate = $master.Templates["System/Media/Unversioned/Jpeg"];

cd master:"\media library\FCL\Illustration";

Get-ChildItem -recurse | ForEach-Object { if ($_.TemplateName -eq "Jpeg") { $_.ChangeTemplate($entryTemplate);Write-Host "Item id: " $.ID " - Template id: " $.TemplateId } };