sample usage of the centerImageView.js file

index.js

var win, parentView, imageView;
var initView;

// copy the centerImageView code here

initView = function() {
    win = Ti.UI.createWindow({
        backgroundColor: "#cccccc"
    });
    parentView = Ti.UI.createView({
        height: Ti.Platform.displayCaps.platformHeight,
        width: Ti.Platform.displayCaps.platformWidth,
        borderRadius: 0
    });
    imageView = Ti.UI.createImageView({
        image: "/images/my_image.jpg"
    });

    // we assume here that the image has a dimension of 600x400, therefore the ratio is 3:2.
    // then you can pass {width: 3, height: 2} or {width: 600, height: 400} as the first argument.
    // you can also call this after postlayout if you don't know the dimension of the image.
    // you can then pass the imageView itself as the first argument.
    centerImageView({
        width: 3,
        height: 2
    }, parentView, imageView);

    parentView.add(imageView);
    win.add(parentView);

    win.open();
};

initView();