El siguiente script desarrollado en PowerShell y dependiente del programa de terceros IrfanView, sirve para convertir todos los archivos de imagen del directorio actual, a formato JPG.

En la sección "Variables" dentro del script pueden personalizar la calidad de codificación JPG y los tipos de archivos de imagen a procesar entre otras cosas configurables.

---

<#
===========================================================================================
|                                                                                         |
|                                        Variables                                        |
|                                                                                         |
===========================================================================================
#>
 
$inputDirectoryPath = "$PSScriptRoot"
$fileNameSearchPattern = "*.*"
$imageExts = @("avif", "bmp", "jp2", "jpg", "png", "tga", "tif", "webp")
$recurse = $false
 
$irfanviewFullPath = "C:\Program Files\IrfanView\i_view64.exe"
$jpgQuality = 95
$overwriteConfirm = $true
$sendToRecycleBinConvertedFiles = $true
 
<#
===========================================================================================
|                                                                                         |
|                                    Functions                                            |
|                                                                                         |
===========================================================================================
#>
 
function Show-WelcomeScreen {
    Clear-Host
    Write-Host ""
    Write-Host " $($host.ui.RawUI.WindowTitle)"
    Write-Host " +===========================================+"
    Write-Host " |                                           |"
    Write-Host " | This script will search for image files   |"
    Write-Host " | in the current working directory, and use |"
    Write-Host " | IrfanView to convert them to JPG format.  |"
    Write-Host " |                                           |"
    Write-Host " +===========================================+"
    Write-Host ""
    Write-Host " Script Settings         " -ForegroundColor DarkGray
    Write-Host " ========================" -ForegroundColor DarkGray
    Write-Host " Input Directory Path....: $inputDirectoryPath" -ForegroundColor DarkGray
    Write-Host " Recursive File Search...: $recurse" -ForegroundColor DarkGray
    Write-Host " Search File Name Pattern: $fileNameSearchPattern" -ForegroundColor DarkGray
    Write-Host " Search File Extensions..: $($imageExts -join ', ')" -ForegroundColor DarkGray
    Write-Host " IrfanView Full Path.....: $irfanviewFullPath" -ForegroundColor DarkGray
    Write-Host " JPG Quality.............: $jpgQuality%" -ForegroundColor DarkGray
    Write-Host " Confirm Overwrite JPG...: $overwriteConfirm" -ForegroundColor DarkGray
    Write-Host " Recycle Converted Files.: $sendToRecycleBinConvertedFiles" -ForegroundColor DarkGray
    Write-Host ""
}
 
function Confirm-Continue {
    Write-Host " Press 'Y' key to continue or 'N' to exit."
    Write-Host ""
    Write-Host " -Continue? (Y/N)"
    do {
        $key = $Host.UI.RawUI.ReadKey("NoEcho,IncludeKeyDown")
        $char = $key.Character.ToString().ToUpper()
        if ($char -ne "Y" -and $char -ne "N") {
            [console]::beep(1500, 500)
        }
    } while ($char -ne "Y" -and $char -ne "N")
    if ($char -eq "N") {Exit(1)}
}
 
function Validate-Parameters {
 
    if (-not (Test-Path -LiteralPath $inputDirectoryPath -PathType Container)) {
        Write-Host " Input directory path does not exists!" -BackgroundColor Black -ForegroundColor Red
        Write-Host ""
        Write-Host " Press any key to exit..."
        $key = $Host.UI.RawUI.ReadKey("NoEcho, IncludeKeyDown")
        Exit(1)
    }
 
    if (-not (Test-Path -LiteralPath $irfanviewFullPath -PathType Leaf)) {
        Write-Host " Irfanview file path does not exists!" -BackgroundColor Black -ForegroundColor Red
        Write-Host ""
        Write-Host " Press any key to exit..."
        $key = $Host.UI.RawUI.ReadKey("NoEcho, IncludeKeyDown")
        Exit(1)
    }
 
    if ($imageExts.Count -eq 0) {
        Write-Host " No image file extensions were specified!" -BackgroundColor Black -ForegroundColor Red
        Write-Host ""
        Write-Host " Press any key to exit..."
        $key = $Host.UI.RawUI.ReadKey("NoEcho, IncludeKeyDown")
        Exit(1)
    }
 
}
 
function Convert-Files {
    Clear-Host
    Add-Type -AssemblyName Microsoft.VisualBasic
 
    $imageFiles = $null
    if ($recurse) {
        $imageFiles = Get-ChildItem -LiteralPath $inputDirectoryPath -Filter $fileNameSearchPattern -Recurse | Where-Object { $imageExts -contains $_.Extension.ToLower().TrimStart('.') }
    } else {
        $imageFiles = Get-ChildItem -LiteralPath $inputDirectoryPath -Filter $fileNameSearchPattern | Where-Object { $imageExts -contains $_.Extension.ToLower().TrimStart('.') }
    }
 
    foreach ($imageFile in $imageFiles) {
        Write-Host " Converting to JPG: $($imageFile.FullName.Replace($inputDirectoryPath, "."))"
 
        $fileNameWithoutExtension = [System.IO.Path]::GetFileNameWithoutExtension($imageFile.Name)
        $outputFilePath = Join-Path -Path ($imageFile.Directory.FullName) -ChildPath "$fileNameWithoutExtension.jpg"
 
        if ((Test-Path -LiteralPath $outputFilePath -PathType Leaf) -and ($overwriteConfirm)) {
            # El archivo no existe o no se debe sobrescribir
            Write-Warning " Output JPG file already exists but `$overwriteConfirm variable is disabled."
            Write-Warning " The output JPG file will be overwitten if you continue."
            Write-Host ""
            Confirm-Continue
            Write-Host ""
        }
 
        $exitCode = $null
        try {
            $procStartInfo = New-Object System.Diagnostics.ProcessStartInfo
            $procStartInfo.FileName = $irfanviewFullPath
            $procStartInfo.Arguments = "`"$($imageFile.FullName)`" /jpgq=$jpgQuality /convert=`"$outputFilePath`""
            $procStartInfo.UseShellExecute = $false
            $process = New-Object System.Diagnostics.Process
            $process.StartInfo = $procStartInfo
            $process.Start() | Out-Null
            $process.WaitForExit()
            $exitCode = $process.ExitCode
        } catch {
            Write-Host ""
            Write-Host " Error running IrfanView process." -BackgroundColor Black -ForegroundColor Red
            Write-Host ""
            Write-Error -Message ($_.Exception.Message)
            Write-Host ""
            Write-Host " Press any key to exit..."
            $key = $Host.UI.RawUI.ReadKey("NoEcho, IncludeKeyDown")
            Exit(1)
        }
 
        if ($exitCode -eq 0) {
            Write-Host " File converted successfully." -ForegroundColor DarkGreen
            if ($sendToRecycleBinConvertedFiles) {
                [Microsoft.VisualBasic.FileIO.FileSystem]::DeleteFile($imageFile.FullName, 'OnlyErrorDialogs', 'SendToRecycleBin')
                Write-Host " File sent to recycle bin." -ForegroundColor DarkGray
            }
            Write-Host ""
        } else {
            Write-Host " Error converting file to JPG. IrfanView Exit Code: $exitCode" -BackgroundColor Black -ForegroundColor Red
            Write-Host ""
        }
    }
}
 
function Show-GoodbyeScreen {
    Write-Host " Operation Completed!" -BackgroundColor Black -ForegroundColor Green
    Write-Host ""
    Write-Host " Press any key to exit..."
    $key = $Host.UI.RawUI.ReadKey("NoEcho, IncludeKeyDown")
    Exit(0)
}
 
<#
===========================================================================================
|                                                                                         |
|                                         Main                                            |
|                                                                                         |
===========================================================================================
#>
 
[System.Console]::Title = "Convert image files to JPG - by Elektro"
#[System.Console]::SetWindowSize(146, 27)
[CultureInfo]::CurrentUICulture = "en-US"
 
try { Set-ExecutionPolicy -ExecutionPolicy "Unrestricted" -Scope "Process" } catch { }
 
Show-WelcomeScreen
Validate-Parameters
Confirm-Continue
Convert-Files
Show-GoodbyeScreen