Problem supplying Byte array input(Internally base64 encoded data) to WebService

Hi Forum,

I am new to SOAP UI Tool. I am testing a WebService  through SOAP UI.

The WebService accepts one attachment and some meta data.

The signature of the exposed method is public String uploadDoc(byte[] encodedContentByteArray, String[] indices)

The first argument is a byte array which is internally base64 encoded content.

My problem is how should I convert the data first to byte array and then encode the data to sent.

Is there any tool available to conert a document or image to byte array?

I m able to call the WebService with the Java client. I am able to get the document image.
Any help is highly appreciated.