Photoshop says image is centered but it's not

I made the message in my script easier to understand You can have Photoshop show your layer center relative to the document center.

// enable double-clicking from Mac Finder or Windows Explorer
#target photoshop 									// this command only works in Photoshop CS2 and higher
app.bringToFront();									// bring application forward for double-click events
var startRulerUnits = app.preferences.rulerUnits;	// Save the current preferences
app.preferences.rulerUnits = Units.PIXELS;			// Set Photoshop to use pixels 
try{
	var LB = activeDocument.activeLayer.bounds;
	var LWidth = (LB[2].value) - (LB[0].value);
	var LHeight = (LB[3].value) - (LB[1].value);
	//MarkX(activeDocument.width.value/ 2);
	MarkX((LB[0].value + LWidth/2));
	MarkX(LB[0].value);
	MarkX(LB[2].value);
	//MarkY(activeDocument.height.value/2);
	MarkY((LB[1].value + LHeight/2));
	MarkY(LB[1].value);	
	MarkY(LB[3].value);
	alert("'" + activeDocument.activeLayer.name + "' Layer Bounds\nTop Left " +  LB[0].value + "X," +  LB[1].value + "Y   Bottom Right "  +  LB[2].value + "X," +  LB[3].value
		+ "Y\nWidth " +  LWidth + "px   Height " + LHeight +"px" 
		+ "\nLayer center " + (LB[0].value + LWidth/2) + "X," +  (LB[1].value + LHeight/2) +"Y"
		+ "\nDocument center  " + (activeDocument.width.value/ 2) + "X," +  (activeDocument.height.value/2) +"Y"
		+ "\nRelative difference  " + ((LB[0].value + LWidth/2) -(activeDocument.width.value/ 2) )+ "X," + ((LB[1].value + LHeight/2) -(activeDocument.height.value/2)) +"Y"		
		, "Layer Bounds Info");
}
catch(e){alert("Requires a layer targered");}
app.preferences.rulerUnits = startRulerUnits;			// Return the app preferences
function MarkX(x) {
// =======================================================
var idMk = charIDToTypeID( "Mk  " );
    var desc61 = new ActionDescriptor();
    var idNw = charIDToTypeID( "Nw  " );
        var desc62 = new ActionDescriptor();
        var idPstn = charIDToTypeID( "Pstn" );
        var idPxl = charIDToTypeID( "#Pxl" );
        desc62.putUnitDouble( idPstn, idPxl, x);
        var idOrnt = charIDToTypeID( "Ornt" );
        var idOrnt = charIDToTypeID( "Ornt" );
        var idVrtc = charIDToTypeID( "Vrtc" );
        desc62.putEnumerated( idOrnt, idOrnt, idVrtc );
    var idGd = charIDToTypeID( "Gd  " );
    desc61.putObject( idNw, idGd, desc62 );
executeAction( idMk, desc61, DialogModes.NO );
}
function MarkY(y) {
// =======================================================
var idMk = charIDToTypeID( "Mk  " );
    var desc63 = new ActionDescriptor();
    var idNw = charIDToTypeID( "Nw  " );
        var desc64 = new ActionDescriptor();
        var idPstn = charIDToTypeID( "Pstn" );
        var idPxl = charIDToTypeID( "#Pxl" );
        desc64.putUnitDouble( idPstn, idPxl, y );
        var idOrnt = charIDToTypeID( "Ornt" );
        var idOrnt = charIDToTypeID( "Ornt" );
        var idHrzn = charIDToTypeID( "Hrzn" );
        desc64.putEnumerated( idOrnt, idOrnt, idHrzn );
    var idGd = charIDToTypeID( "Gd  " );
    desc63.putObject( idNw, idGd, desc64 );
executeAction( idMk, desc63, DialogModes.NO );
}

Zooming in to 100%, it does appear to look how it should. It's puzzling to me how my eyes see it differently when I'm zoomed out. The image itself is an even 1500 x 1500.