tell application "Finder"
set theSelected to the selection as alias
set duplicatedFolder to duplicate theSelected to path to desktop folder
set duplicatedFolder to duplicatedFolder as alias
end tell
set longSide to the text returned of (display dialog "Set a size in pixels for longest side of images." default answer "1920")
set foldPath to quoted form of POSIX path of duplicatedFolder
set finalPath to foldPath & "*.jpg"
set shellScpt to "sips -Z " & longSide & " " & finalPath
do shell script shellScpt