I have successfully created a RESTful web service to GET a Blob object (photo) and then created a RESTful service reference to call it from an application. However, I cannot get the Blob to render as an image, because the Blob Column attributes won't recognize the collection that gets populated by the web service reference as a table--I keep getting an error that 'apex collection' can't be found. Is the only option to create a table and load the collection into the table, and then set the attributes?
See here on working with APEX Collections from Web Services: http://www.apexninjas.com/blog/2011/05/using-rest-web-services-in-apex/
And rendering images from BLOB: http://www.apexninjas.com/blog/2011/09/uploading-and-displaying-images-in-apex/