base64 coding is used to embed images inside the XML input/output. Taverna has internal services based in beanshell script that code and decode base64 into byte (binary) structure allowing for the image to be viewed as result or saved in a file.
The histogram process accepts an image as input and calculates the images histogram and returns a PNG image. The PNG image will be automatically encoded in base64
Adding a base64 decoding service (located in Local services > base64), its possible to see the PNG image as a result
Notice that the result is no longer a base64 string but a pure PNG image
--Wikiadmin 17:13, 10 January 2011 (UTC)