Convert all images to base64

htmlImagesToBaseSixtyFour.ps1

$md = <# PATH TO MARKDOWN FILE #>
$images = Select-String -Pattern "(?<=!\[[^\(]+\()[^\)]+(?=\))" -Path $md | ForEach-Object { $_.Matches.Value }
$html = <# PATH TO HTML FILE #>
$images = Select-String -Pattern "(?<=src=`")[^`"]+(?=\))" -Path $html | ForEach-Object { $_.Matches.Value }
$imagesBase64 = [string[]]::new($images.Count)
foreach($image in $images){ 
  try {
    # $filehandle = [System.IO.File]::Open((Join-Path -Path (Split-Path -Path $md -Parent) -ChildPath $image),[System.IO.FileMode]::Open)
    $filehandle = [System.IO.File]::Open($image,[System.IO.FileMode]::Open)
    $bytes = [byte[]]::new($filehandle.Length)
    $filehandle.Read($bytes,0,$filehandle.Length) | Out-Null
  } 
  finally {
    $filehandle.Dispose()
  }
  $base64 = [System.Convert]::ToBase64String($bytes)
  $i = $images.IndexOf($image)
  $imagesBase64[$i] = "data:image/png;base64,$base64"
  $base64 = $null
 }
Get-Content -Path $html | ForEach-Object {
  $line = $_
  foreach($image in $images){
    $imagePattern = "(?<=src=`").*$([regex]::Escape($image))"
    if($line -match $imagePattern) {
      $i = $images.IndexOf($image)
      $line = $line -replace $imagePattern, ($imagesBase64[$i])
    }
  }
  $line | Write-Output
} | Out-File $env:TEMP\uow.html