Revert "Rely on opts being pre-populated"

This reverts commit bf1f3b8d.

javascript/imageviewer.js

@@ -102,7 +102,14 @@ onUiUpdate(function(){
 		fullImg_preview.forEach(galleryImageHandler);
 	}
 
-    if(Object.keys(opts).length == 0) return;
+    if(Object.keys(opts).length != 0) return;
+
+    json_elem = gradioApp().getElementById('settings_json')
+    if(json_elem == null) return;
+
+    textarea = json_elem.querySelector('textarea')
+    jsdata = textarea.value
+    opts = JSON.parse(jsdata)
 
     if(!window.lightbox_settings_applied){
         window.lightbox_settings_applied = true;