Finds image in a folder with the suffix "-hd.png", shrinks them by 50% and exports them as a file with the "-hd" removed.

png_batch_resize.js

/*
*
*  Finds image in a folder with the suffix "-hd.png", shrinks them by 50% and exports them 
*  as a file with the "-hd" removed.
*
*  Rob Seward 2011
*/

$.level=2; //activate debugger if there are problems

var dlg=
"dialog{text:'Script Interface',bounds:[100,100,500,220],"+
"folder:EditText{bounds:[10,40,310,60] , text:'' ,properties:{multiline:false,noecho:false,readonly:false}},"+
"recurse:Checkbox{bounds:[260,10,361,27] , text:'Recurse Folders' },"+
"Browse:Button{bounds:[320,40,390,61] , text:'<<' },"+
"statictext0:StaticText{bounds:[10,10,240,27] , text:'Please select Folder' ,properties:{scrolling:undefined,multiline:undefined}},"+
"Process:Button{bounds:[10,80,190,101] , text:'Process' },"+
"button2:Button{bounds:[210,80,390,101] , text:'Cancel' }};"
var win = new Window(dlg,'test');
win.center();
win.folder.enabled=false;
win.Browse.onClick = function() { 
	selectedFolder = Folder.selectDialog( "Please select a folder to process");  
	if(selectedFolder != null) win.folder.text =  decodeURI(selectedFolder); 
}

win.Process.onClick = function() { 
	if(win.folder.text == '') {
		alert("No folder has been selected!");
		return;
	}
	win.close(1);
	folderList=[];
	if(win.recurse.value){
		processFolder(selectedFolder);
		folderList.unshift(selectedFolder);
	}else{
		folderList.unshift(selectedFolder);
	}
	ProcessFiles();
	function ProcessFiles(){
		for(var a in folderList){
			var fileList = folderList[a].getFiles(/\.(jpg|png)$/i);
			for(var s in fileList){
				var startRulerUnits = app.preferences.rulerUnits;
				app.preferences.rulerUnits = Units.PIXELS;
				var file = fileList[s];
				open(file);
				var Name =activeDocument.name;//.match(/(.*)\.[^\.]+$/)[1];
				//alert(Name);
				if(/-hd.png/.test(Name)){
					halveImage();
					var saveFileName = activeDocument.name.replace(/-hd.png/,".png");
					var saveFile = File(activeDocument.path+"/"+saveFileName);
					SavePNG(saveFile);
				}
				app.activeDocument.close(SaveOptions.DONOTSAVECHANGES);
				app.preferences.rulerUnits = startRulerUnits;
			}
		}
	}
	function processFolder(folder) {
		var fileList = folder.getFiles()
		for (var i = 0; i < fileList.length; i++) {
			var file = fileList[i];
			if (file instanceof Folder) {
				folderList.push(file);  
				processFolder(file);
			}
		}
	}
}

win.show();
function halveImage() { 
	var doc=activeDocument;
	var newWidth = doc.width * 0.5;
	var newHeight = doc.height * 0.5;
	doc.resizeImage(newWidth, newHeight, undefined, ResampleMethod.BICUBIC);
}

function SavePNG(savefile){	
	opts = new ExportOptionsSaveForWeb();
    opts.format = SaveDocumentType.PNG;
    opts.PNG8 = false;
    opts.quality = 100; 
	activeDocument.exportDocument(savefile, ExportType.SAVEFORWEB, opts);
}