diff --git a/schema/course.schema.json b/schema/course.schema.json
index d755b19..e2fe24a 100644
--- a/schema/course.schema.json
+++ b/schema/course.schema.json
@@ -55,7 +55,6 @@
               "properties": {
                 "_src": {
                   "type": "string",
-                  "isObjectId": true,
                   "title": "Source",
                   "description": "This image will appear above the menu page title",
                   "_backboneForms": {
@@ -81,7 +80,6 @@
               "properties": {
                 "_xlarge": {
                   "type": "string",
-                  "isObjectId": true,
                   "title": "Extra large",
                   "description": "Extra large background image, e.g. hd laptop/desktop computers",
                   "_backboneForms": {
@@ -91,7 +89,6 @@
                 },
                 "_large": {
                   "type": "string",
-                  "isObjectId": true,
                   "title": "Large",
                   "description": "Large background image, e.g. laptop/desktop computers",
                   "_backboneForms": {
@@ -101,7 +98,6 @@
                 },
                 "_medium": {
                   "type": "string",
-                  "isObjectId": true,
                   "title": "Medium",
                   "description": "Medium background image, e.g. tablet devices",
                   "_backboneForms": {
@@ -111,7 +107,6 @@
                 },
                 "_small": {
                   "type": "string",
-                  "isObjectId": true,
                   "title": "Small",
                   "description": "Small background image, e.g. mobile / cellphones",
                   "_backboneForms": {
@@ -232,7 +227,6 @@
                   "properties": {
                     "_xlarge": {
                       "type": "string",
-                      "isObjectId": true,
                       "title": "Extra large",
                       "description": "Extra large background image, e.g. hd laptop/desktop computers",
                       "_backboneForms": {
@@ -242,7 +236,6 @@
                     },
                     "_large": {
                       "type": "string",
-                      "isObjectId": true,
                       "title": "Large",
                       "description": "Large background image, e.g. laptop/desktop computers",
                       "_backboneForms": {
@@ -252,7 +245,6 @@
                     },
                     "_medium": {
                       "type": "string",
-                      "isObjectId": true,
                       "title": "Medium",
                       "description": "Medium background image, e.g. tablet devices",
                       "_backboneForms": {
@@ -262,7 +254,6 @@
                     },
                     "_small": {
                       "type": "string",
-                      "isObjectId": true,
                       "title": "Small",
                       "description": "Small background image, e.g. mobile / cellphones",
                       "_backboneForms": {