Yeah... I do know that K2 stores images in a, lets say, "strange" way. Can we than do something like this:
1. Make extra field with name IMAGE that would be a text field, or radio button with "yes" and "no" choice. All the items with image will have value "yes" and all without image will have value "no"
2. Check the value for this extra field in NSP and show only the items with value YES

Or if the extra field is too complicated to use, can we use the "image_credits" or "image_caption" field in similar way?