Easy way to extract all pixel Lab values - please help!

File.prototype.readByte = function() {
  return this.read(1).charCodeAt(0);
};
function convertByteToSignedByte(num){
     var dec = (num | (num % 256))-128
     return dec;
};
function convertByteToLum( num){
     var dec = Math.round((num/256)*100);
     return dec;
};
function main(){
if(!documents.length) return;
if(activeDocument.mode != DocumentMode.LAB) {
    alert("Please convert this document to Lab mode\r Then re-run this script");
    return;
    }
var Name = decodeURI(app.activeDocument.name).replace(/\.[^\.]+$/, '');
try{
var Path = activeDocument.path;
}catch(e){var Path = '~/Desktop';}
var rawFile = new File(Path +"/"+Name +".raw");
saveAsRaw(rawFile);
var csvFile = new File(Path +"/"+Name +".csv");
var W = activeDocument.width.as('px');
scan_pixel=50;
CountW=0;
CountH=0;
rawFile.encoding = 'BINARY';
rawFile.open('r');
csvFile.open('w');
csvFile.writeln('X,Y,L,a,b');
while(!rawFile.eof){
    csvFile.write(CountW+',');
    csvFile.write(CountH+',');
     csvFile.write(convertByteToLum(rawFile.readByte())+',');
     csvFile.write(convertByteToSignedByte(rawFile.readByte())+',');
     csvFile.writeln(convertByteToSignedByte(rawFile.readByte()));
     if(CountW >= 3776){
         CountH=CountH+scan_pixel;
         CountW=0;
         }else if (CountH <=2520){
     CountW=CountW+scan_pixel;
     } else { return;}
}
csvFile.close();
}
main();
function saveAsRaw(file) {
var desc1 = new ActionDescriptor();
var desc2 = new ActionDescriptor();
desc2.putString( charIDToTypeID('FlCr'), "8BIM" );
desc2.putBoolean( charIDToTypeID('ChnI'), true );
desc1.putObject( charIDToTypeID('As  '), charIDToTypeID('Rw  '), desc2 );
desc1.putPath( charIDToTypeID('In  '), new File( file ) );
desc1.putBoolean( charIDToTypeID('Cpy '), true );
executeAction( charIDToTypeID('save'), desc1, DialogModes.NO );
};

It would have to be done differently as an average needs to be done. The following script will do 50pixel squares and write the results to the CSV file...

main();
function main(){
if(!documents.length) return;
if(activeDocument.mode != DocumentMode.LAB) {
    alert("Please convert this document to Lab mode\r Then re-run this script");
    return;
    }
var Name = decodeURI(app.activeDocument.name).replace(/\.[^\.]+$/, '');
try{
var Path = activeDocument.path;
}catch(e){var Path = '~/Desktop';}
var csvFile = new File(Path +"/"+Name +".csv");
csvFile.open('w');
csvFile.writeln("X,Y,L,a,b");
snapShot();
var startRulerUnits = preferences.rulerUnits;
preferences.rulerUnits = Units.PIXELS;
doc = app.activeDocument;
app.displayDialogs = DialogModes.NO;
doc.flatten();
var tilesAcross =activeDocument.width/50; //50 pixels
var tilesDown =activeDocument.height/50; //50 pixels
var tileWidth = parseInt(doc.width/tilesAcross);
var tileHeight = parseInt(doc.height/tilesDown);
ProcessFiles(tilesDown,tilesAcross,tileWidth,tileHeight);
revertToLastSnapshot();
app.preferences.rulerUnits = startRulerUnits;      
csvFile.close();
function ProcessFiles(Down,Across,offsetX,offsetY,SaveFiles){
var solidColour = new SolidColor();
TLX = 0; TLY = 0; TRX = offsetX; TRY = 0;
BRX = offsetX; BRY = offsetY; BLX = 0; BLY = offsetY;
 for(var a = 0; a < Down; a++){
  for(var i = 0;i <Across; i++){
    activeDocument.selection.select([[TLX,TLY],[TRX,TRY],[BRX,BRY],[BLX,BLY]], SelectionType.REPLACE, 0, false); 
    activeDocument.activeLayer.applyAverage();
                getColour(TLX,TLY);
    app.activeDocument.selection.deselect();
TLX = offsetX * (i+1) ; TRX  = TLX + offsetX; BRX = TRX; BLX = TLX;  
    }
TLX = 0; TLY = offsetY * (a +1); TRX = offsetX; TRY = offsetY * (a +1);
BRX = offsetX; BRY = TRY + offsetY; BLX = 0; BLY = (offsetY * (a +1)+offsetY); 
 }
}
function getColour(X,Y){
solidColour=app.activeDocument.colorSamplers.add([new UnitValue( Number(X)+1,'px'),new UnitValue(Number(Y)+1,'px' )]).color;
                var L = Math.round(solidColour.lab.l);
                var a = Math.round(solidColour.lab.a);
                var b = Math.round(solidColour.lab.b);
                csvFile.writeln((Number(X)+1)+","+(Number(Y)+1)+","+L+","+a+",",b);
                app.activeDocument.colorSamplers.removeAll();
}
function snapShot() {
    var desc9 = new ActionDescriptor();
        var ref5 = new ActionReference();
        ref5.putClass( charIDToTypeID('SnpS') );
    desc9.putReference( charIDToTypeID('null'), ref5 );
        var ref6 = new ActionReference();
        ref6.putProperty( charIDToTypeID('HstS'), charIDToTypeID('CrnH') );
    desc9.putReference( charIDToTypeID('From'), ref6 );
    desc9.putEnumerated( charIDToTypeID('Usng'), charIDToTypeID('HstS'), charIDToTypeID('FllD') );
    executeAction( charIDToTypeID('Mk  '), desc9, DialogModes.NO );
};
function revertToLastSnapshot() { 
   var doc = app.activeDocument; 
   var hsObj = doc.historyStates; 
   var hsLength = hsObj.length; 
   for (var i=hsLength - 1;i>-1;i--) { 
     if (hsObj.snapshot) { 
       doc.activeHistoryState = doc.historyStates.getByName('Snapshot ' + i); 
       break; 
     } 
   } 
}
}