Using java script in Adobe Livecycle Designer ES how can I refer to a specific field (Picture) in a subform which has been repeated a few time to allow me to make that specific occurrence of that field visible or invisble when required when a user clicks on a button for that purpose. .
that should be all you need. If the picture is wrapped in a subform and you want to hide the subform they you would change the reference from Picture or whatever your field is. Based on your hierarchy it looks like it would be: