There is HSSFFooter.PICTURE_FIELD in HSSFFooter, which has a sequence field "&G", that assumes that picture is someway attached to the proper section of footer/header and should be displayed by Excel. But the only way of attaching image to worksheet is patriarch.createPicture method which has HSSFClientAnchor parameter. HSSFClientAnchor supposes that image can be attached to cell(s), but there is no way to add it to header/footer section.
Header and footer pictures are attached in a different way. Excel seems to store this data in the Header / Footer Picture Record (866h) which is not yet supported. I'm going to look into it but now sure how soon. Regards, Yegor
Created attachment 25192 [details] Trintech examples
Related open bugs: bug 53309 - similar request for XSSFWorkbooks bug 58422 - similar request for SXSSFWorkbooks bug 58237 - similar request for slideshow presentations