Get image url from model good practice?

the autoloader only loads files from the application/objects directory
if the proprietati_model was inside of this directory than remove it and copy it to the application/models directory, because a model should not be there

You did not understand, public function autoloadCoreObjects($class) where $class is the name of the model yes?

Well my model name was: Proprietati_model because in my models folder this is how I use to name my models:

Properties_model.php with class Properties_model
Products_model.php  with class Products_model

Maybe your models was

Properties.php with class Properties
Products.php with class Products

and you did not need that explode for underscore.