Small PowerShell script to bulk upscale all files within a directory using Real-ESRGAN

upscale.ps1

# Requirements:
# 
# You need to have Real-ESRGAN installed and within your PATH.
# You can get Real-ESRGAN at the offical repository at
# https://github.com/xinntao/Real-ESRGAN
# 
# Installation:
# 
# Copy the script into any directory that is in your PATH variable. 
# You can call it from PS using the file name i.e. upscale.
#
# You can find more information on how to edit the PATH and other 
# environment variables on the offical Microsoft documentation:
# https://learn.microsoft.com/en-us/windows/win32/procthread/environment-variables
#
# Usage:
#  > upscale
#  > upscale -needle *.png
#  > upscale -needle *.png -extension webp -subdirectory ./target
#
# Author: Patrick Henninger
# License: GNU GPL v3
#
PARAM (
  [string]$needle='*.jpg',
  [string]$extension='png',
  [string]$subdirectory='./upscaled'
)

if ($subdirectory) {
    # Create folder if does not exist
    if (-Not (Test-Path -Path $subdirectory)) {
        New-Item -Path $subdirectory -ItemType 'Directory' -Force
    }

    # Make sure the path is good
    $subdirectory = (Resolve-Path $subdirectory).Path
}

Get-ChildItem -Path (Get-Location).Path -Filter $needle | Foreach-Object {
    # Only process files
    if ($_.GetType().FullName -ne "System.IO.FileInfo") {
        # We have to use return instead of continue here
        # see: https://stackoverflow.com/a/7763698/5703628
        return
    }

    # Build the target file name
    [string]$target = $_.Name + ".$extension"

    # Prepend the subdirectory in case it is defined
    if ($subdirectory) {
        $target = "$subdirectory\$target"
    }

    # Upscale using Real-ESRGAN
    realesrgan -i $_.FullName -o $target
}