ConvertTo-AsciiArt

ConvertTo-AsciiArt.ps1

<#
.DESCRIPTION
  Converts an image to ASCII art.

.PARAMETER Path
  The path to an image file to convert to ASCII.  This can be any image format supported by System.Drawing.Bitmap.
  
.PARAMETER Uri
  The URI for an image to download and convert to ASCII.  This can be any image format supported by System.Drawing.Bitmap.
  
.PARAMETER Bytes
  A byte array representing an image to convert to ASCII.  This can be any image format supported by System.Drawing.Bitmap.

.PARAMETER Invert
  Invert the colors so they show up correctly on the PowerShell console (which usually has a dark background with light text).

.PARAMETER Width
  The width to resize the image to.  If width is specified but not height, then the image will be scaled proportionately.  If neither width nor height are specified the image will be displayed at it's native resolution.
  
.PARAMETER Height
  The height to resize the image to.  If height is specified but not width, then the image will be scaled proportionately.  If neither width nor height are specified the image will be displayed at it's native resolution.
  
.EXAMPLE
  ConvertTo-AsciiArt -Uri http://bit.ly/1fUuN72 -Width 100 -Invert
  
  Downloads an image from http://bit.ly/1fUuN72 and displays it in the console.

.EXAMPLE
  Get-ChildItem -Path c:\Windows\Web -Include *.jpg,*.png -Recurse | Get-Random | ConvertTo-AsciiArt -Invert -Width 119
  
  Grabs a random image included with Windows and displays it in the console.  Note the default console window is 120 characters, but the last one does not print so this sets the width to 119.

.LINK
  http://msdn.microsoft.com/en-us/library/system.drawing.bitmap.aspx
#>
function ConvertTo-AsciiArt {
  param(
    [Parameter(ParameterSetName="File",ValueFromPipeline=$true,ValueFromPipelineByPropertyName=$true)]
    [Alias("Fullname")]
    [string]$Path,
    
    [Parameter(ParameterSetName="Bytes")]
    [Byte[]]$Bytes,
    
    [Parameter(ParameterSetName="Uri")]
    [Uri]$Uri,
    
    [switch]$Invert,
    
    [int]$Width,
    
    [int]$Height
  )
  begin {
    $CharMap = "█▓▒░#+-. "
    $WtoB = $BtoW.ToCharArray()
    [Array]::Reverse($WtoB)
    if($Invert) {
      $CharMap = $CharMap.ToCharArray()
      [Array]::Reverse($CharMap)
    }
  }
  process {
    switch($PsCmdlet.ParameterSetName) {
      "File" {
        $Bmp = New-Object System.Drawing.Bitmap($Path)
      }
      "Bytes" {
        $MS = New-Object System.IO.MemoryStream(,$Bytes)
        $Bmp = New-Object System.Drawing.Bitmap($MS)
        $MS.Close()
      }
      "Uri" {
        $Response = Invoke-WebRequest -Uri $Uri -UseBasicParsing
        $MS = New-Object System.IO.MemoryStream(,$Response.Content)
        $Bmp = New-Object System.Drawing.Bitmap($MS)
      }
    }
    if($Width) {
      if(!$Height) {
        $Height = ($Width * $Bmp.Height) / $Bmp.Width
      }
    }
    if($Height) {
      if(!$Width) {
        wb/h = a
        $Width = ($Bmp.Width * $Height) / $Bmp.Height
      }
    }
    if($Width -and $Height) {
      $Bmp = New-Object System.Drawing.Bitmap($Bmp, $Width, $Height)
    }
    
    for($x = 0; $x -lt $Bmp.Height; $x += 2) {
      $RowBuilder = New-Object Text.StringBuilder($Bmp.Width + 2)
      for($y = 0; $y -lt $Bmp.Width; $y++) {
        $TopBrightness = $Bmp.GetPixel($y, $x).GetBrightness()
        if($x + 1 -lt $Bmp.Height) {
          $BottomBrightness = $Bmp.GetPixel($y, $x + 1).GetBrightness()
          $Brightness = ($TopBrightness + $BottomBrightness) / 2
        } else {
          $Brightness = $TopBrightness
        }
        $Char = $CharMap[ [int](($CharMap.Length - 1) * $Brightness)]
        $RowBuilder.Append($Char) > $Null
      }
      $RowBuilder.ToString()
    }
  }
}