RGB values into array?

There is yet another way and that is to use a bitmap in Bridge.

Here is an example it requires a file selected in Bridge, then run the script from ExtendScript Toolkit.

//To be run from ExtendScript Toolkit
#target bridge
getImage();
function getImage() {
var image, bit, data;
image = app.document.selections[0];
bit = new BitmapData( image.spec );
//resize
bit = bit.resize( 100, 'bicubicSharper' );
//get pixel data
data = readColorData( bit );
//example of geing the hex value at x,y
alert(data.x40y34);
//save object to file for later use.
var f = new File(Folder.desktop +"/objData.dat");
f.open('w');
f.write(data.toSource());
f.close();
//empty data object
data={};
//example of loading and using the object
f.open('r');
var newOBJ = eval(f.read());
f.close();
alert("X = 20 Y = 23 Hex Value = " + newOBJ.x20y23);
alert("X = 19 Y = 33 Hex Value = " + newOBJ.x19y33);

};
function readColorData( bitMap ) {
   var pix, row, x, y;
   //create and populate dynamic object to hold pixel data
   mainObj = {};
   for ( y = 0; y < bitMap.height; y++ ) {
      for ( x = 0; x < bitMap.width; x++ ) {
           mainObj ["x"+x+"y"+y] = new Color(bitMap.getPixel(x,y)).toString().match(/[A-Fa-f0-9]{6}$/);
      };
   };
return mainObj;
};

It's a bit of a hack, but you could probably save it as Photoshop Raw and then read the values directly from the file as binary stream.

Only way I know of, just using javascript is to use the eyedropper tool, which would be beyond slow for this purpose. I've done it with sampling various areas, at the most every 50px, and that can still take up to a half hour for a full 4000X3000 image.