property |NSURL| : a reference to current application’s |NSURL|
property NSArray : a reference to current application’s NSArray
property NSPredicate : a reference to current application’s NSPredicate
property NSURLTypeIdentifierKey : a reference to current application’s NSURLTypeIdentifierKey

set zoomPercent to 0.5

tell application "Finder"
　　set inFiles to selection as alias list
end tell

–指定のAlias listのうち画像のみ抽出
set filRes1 to filterAliasListByUTI(inFiles, "public.image") of me
if filRes1 = {} then return

–選択中のファイルのうちの１つから親フォルダを求め、出力先ファイルパスを組み立てる
set outPathTarg to POSIX path of (first item of filRes1)
set pathString to current application’s NSString’s stringWithString:outPathTarg
set newPath to (pathString’s stringByDeletingLastPathComponent()) as string

repeat with i in filRes1
　　set outPOSIXpath to newPath & "/" & (current application’s NSUUID’s UUID()’s UUIDString()) as string
　　set fRes1 to resizeImage(i, outPOSIXpath, zoomPercent) of me
end repeat

on resizeImage(imagePath, newPath, aZoom as real)
　　–ファイルパスの拡張子を取得する
　　set pathString to current application’s NSString’s stringWithString:imagePath
　　set fileExt to (pathString’s pathExtension()) as string
　　
　　–画像ファイルをNSImageに読み込み
　　set theImage to current application’s NSImage’s alloc()’s initWithContentsOfFile:imagePath — load the file as an NSImage
　　
　　— calculate required sizes
　　set theSize to (theImage’s |size|()) as record
　　
　　set oldWidth to width of theSize
　　set oldHeight to height of theSize
　　
　　set theWidth to oldWidth * aZoom
　　set theHeight to oldHeight * aZoom
　　
　　set newImage to current application’s NSImage’s alloc()’s initWithSize:(current application’s NSMakeSize(theWidth, theHeight))
　　
　　newImage’s lockFocus()
　　theImage’s drawInRect:{origin:{x:0, y:0}, |size|:{width:theWidth, height:theHeight}} fromRect:(current application’s NSZeroRect) operation:(current application’s NSCompositeSourceOver) fraction:1.0
　　newImage’s unlockFocus()
　　
　　set theData to newImage’s TIFFRepresentation()
　　set newRep to current application’s NSBitmapImageRep’s imageRepWithData:theData
　　
　　–元画像のファイルファイルフォーマットに合わせて同じフォーマットに
　　if fileExt is in {"png", "PNG"} then
　　　　set theData to (newRep’s representationUsingType:(current application’s NSPNGFileType) |properties|:{NSImageGamma:1.0})
　　else if fileExt is in {"jpg", "jpeg"} then
　　　　set theData to (newRep’s representationUsingType:(current application’s NSJPEGFileType) |properties|:{NSImageCompressionFactor:1.0})
　　else if fileExt is in {"tif", "tiff"} then
　　　　set theData to (newRep’s representationUsingType:(current application’s NSTIFFFileType) |properties|:(missing value))
　　else if fileExt is in {"bmp"} then
　　　　set theData to (newRep’s representationUsingType:(current application’s NSBMPFileType) |properties|:(missing value))
　　end if
　　
　　set newPath to newPath & "." & fileExt
　　return (theData’s writeToFile:newPath atomically:true)
　　
end resizeImage

–Alias listから指定UTIに含まれるものをPOSIX pathのリストで返す
on filterAliasListByUTI(aList, targUTI)
　　set newList to {}
　　repeat with i in aList
　　　　set j to POSIX path of i
　　　　set tmpUTI to my retUTIfromPath(j)
　　　　set utiRes to my filterUTIList({tmpUTI}, targUTI)
　　　　if utiRes is not equal to {} then
　　　　　　set the end of newList to j
　　　　end if
　　end repeat
　　return newList
end filterAliasListByUTI

–指定のPOSIX pathのファイルのUTIを求める
on retUTIfromPath(aPOSIXPath)
　　set aURL to |NSURL|’s fileURLWithPath:aPOSIXPath
　　set {theResult, theValue} to aURL’s getResourceValue:(reference) forKey:NSURLTypeIdentifierKey |error|:(missing value)
　　
　　if theResult = true then
　　　　return theValue as string
　　else
　　　　return theResult
　　end if
end retUTIfromPath

–UTIリストが指定UTIに含まれているかどうか演算を行う
on filterUTIList(aUTIList, aUTIstr)
　　set anArray to NSArray’s arrayWithArray:aUTIList
　　set aPred to NSPredicate’s predicateWithFormat_("SELF UTI-CONFORMS-TO %@", aUTIstr)
　　set bRes to (anArray’s filteredArrayUsingPredicate:aPred) as list
　　return bRes
end filterUTIList