jquery validation Rules depends on another field

 $('#fu_ImageUpload').rules('add', {
                required: {
                    depends: function () {
                        if ($("#chk_Upload").is(':checked')) {
                            return true;
                        }
                        else {
                            return false;
                         }
                    }
                },
                ImageFormat: {
                    depends: function () {
                        if ($("#chk_PRP").is(':checked')) {
                            return true;
                        }
                        else {
                            return false;
                        }
                    }
                },
messages: {
                    required: "Please  Page.",
                    ImageFormat: "Invalid Image Format"
                }
            });

 jQuery.validator.addMethod("ImageFormat", function (value, element) {
                var ext = value.split('.').pop().toLowerCase();
                switch (ext) {
                    case 'jpg':
                        return true;
                    case 'jpeg':
                        return true;
                    case 'gif':
                        return true;
                        break;
                    default:
                        return false;
                }
            }, "Invalid Image Format.");