I need to send some illustration concepts to a company for appraisal. I've watermarked the images, but as they are black and white and not particularly complicated, it has occurred to me that it's quite easy to be able to remove said watermarks in Photoshop. Firstly, what format should I send them across in - EPS, PDF, JPEG etc? Secondly, is there something that can physically be done to the file in order to make it readable, but uneditable in any way, shape or form?