javascript: function GabeN(ratio, imageurl) {
    this.ratio = ratio;
    this.imageurl = imageurl
}
var getGabeN = {
    init: function(myGabeN) {
        this.myGabeN = myGabeN
    },
    horizontal: function() {
        return this.myGabeN.filter(function(myGabeN) {
            return myGabeN.ratio === "horizontal"
        })
    },
    vertical: function() {
        return this.myGabeN.filter(function(myGabeN) {
            return myGabeN.ratio === "vertical"
        })
    },
    square: function() {
        return this.myGabeN.filter(function(myGabeN) {
            return myGabeN.ratio === "square"
        })
    }
};

function Randomize(images) {
    return Math.floor(Math.random() * images.length)
}
var myGabeN = [new GabeN("horizontal", "http://i.imgur.com/uLMbKmj.jpg"), new GabeN("horizontal", "http://i.imgur.com/5DXQ7tx.jpg"), new GabeN("horizontal", "http://i.imgur.com/dldrXOf.jpg"), new GabeN("horizontal", "http://i.imgur.com/8uH9TQb.jpg"), new GabeN("horizontal", "http://i.imgur.com/7wU40jQ.jpg"), new GabeN("horizontal", "http://i.imgur.com/ajxvdWo.jpg"), new GabeN("vertical", "http://i.imgur.com/aRCPVmX.jpg"), new GabeN("vertical", "http://i.imgur.com/FU2unZO.jpg"), new GabeN("vertical", "http://i.imgur.com/3brJDRx.jpg"), new GabeN("vertical", "http://i.imgur.com/j9KOnWm.jpg"), new GabeN("square", "http://i.imgur.com/sWCcEwV.jpg"), new GabeN("square", "http://i.imgur.com/ecbdpfL.jpg"), new GabeN("square", "http://i.imgur.com/lDkMf5P.jpg"), new GabeN("square", "http://i.imgur.com/qkcP48v.jpg")];

function imageRatio(image) {
    var proportion = image.height / image.width;
    if (proportion > 1) return "vertical";
    else if (proportion === 1) return "square";
    else if (proportion < 1) return "horizontal"
}(function(document) {
    getGabeN.init(myGabeN);
    var images = document.getElementsByTagName("img"),
        length = images.length;
    for (var i = 0; i < length; i++) {
        var ratio = imageRatio(images[i]);
        if (ratio === "horizontal") {
            var number = Randomize(getGabeN.horizontal());
            var img = getGabeN.horizontal()[number];
            images[i].src = img.imageurl
        } else if (ratio === "square") {
            var number = Randomize(getGabeN.square());
            var img = getGabeN.square()[number];
            images[i].src = img.imageurl
        } else if (ratio === "vertical") {
            var number = Randomize(getGabeN.vertical());
            var img = getGabeN.vertical()[number];
            images[i].src = img.imageurl
        }
    }
})(document);