var scrollSpeed = 1; 		// Speed in milliseconds
var step = 1; 				// How many pixels to move per step
var current = 0; 		// The current pixel row
var imageWidth = 50; 	// Background image width
var headerWidth = 50; 	// How wide the header is.

//The pixel row where to start a new loop
var restartPosition = -(imageWidth - headerWidth);

function scrollBg() {
    //Go to next pixel row.
    current -= step;

    //If at the end of the image, then go to the top.
    if (current == restartPosition) {
        current = 0;
    }

    $('#loader-img').css("background-position", current + "px 0");
}

//Calls the scrolling function repeatedly
var init = setInterval("scrollBg()", scrollSpeed);