Alle Pixel eines PNGs mit Formel neu einfärben

# Load needed assemblies
Add-Type -A System.Drawing
Add-Type -A System.Windows.Forms
Add-Type –MemberDefinition '[DllImport("user32.dll")]public static extern bool ShowWindow(IntPtr hWnd, int nCmdShow);' -name Window -namespace W32  

# hide powershell console
[void][W32.Window]::ShowWindow((Get-Process -id $pid).MainWindowHandle, 0) 

# show file chooser dialog
$odlg = New-Object System.Windows.Forms.FolderBrowserDialog
$odlg.Description = "Select source folder"  
if($odlg.ShowDialog() -ne 'OK'){  
    return
}
# show file chooser dialog
$sdlg = New-Object System.Windows.Forms.FolderBrowserDialog
$sdlg.Description = "Select target folder to save modified files to"  
if($sdlg.ShowDialog() -ne 'OK'){  
    return
}

# show color dialog
$colorDialog = New-Object System.Windows.Forms.ColorDialog -Property @{FullOpen = $true}
if ($colorDialog.ShowDialog() -ne 'OK'){  
    return
}
# assign color from dialog to variable
$color = $colorDialog.Color

# Show info
[void][System.Windows.Forms.MessageBox]::Show("Color filter will be applied when you press OK, please wait until the save dialog will be shown!","Color-Filter",0,64)  


foreach($file in (ls $odlg.SelectedPath -Filter *.png -File)){
    # create system drawing image
    $img = [System.Drawing.Image]::FromFile($file.FullName)
    # parse als pixels from image
    for ($x = 0; $x -lt $img.Width; $x++){ 
        for ($y = 0; $y -lt $img.Height; $y++){
            $p = $img.GetPixel($x,$y)
            $img.SetPixel($x,$y,[System.Drawing.Color]::FromArgb($p.A,[int]($color.R/255*$p.R),[int]($color.G/255*$p.G),[int]($color.B/255*$p.B)))
        }    
    }
    $img.Save((join-path $sdlg.SelectedPath $file.Name),'Png')  
    # cleanup handle
    $img.Dispose()
}