scale.js

function scaleImage($img, w, h, targetWidth, targetHeigth) {
    var ratio = targetWidth / w;

    var height = h * ratio;
    var width = w * ratio;

    if (targetHeigth && height > targetHeigth) {
        ratio = targetHeigth / h;

        height = targetHeigth;
        width = w * ratio;
    }

    height = Math.floor(height);
    width = Math.floor(width);

    if ($img) {
        $img.css({
            height: height,
            width: width
        });
    }

    return {width: width, height: height};
}