[XeTeX] XeTeX, PdfTeX and graphics

[Philip TAYLOR]

Rather naively, I had thought that as well as including the
e-TeX extensions and enhancements, XeTeX had included the
PdfTeX extensions as well; I have just discovered that it
does not :-(

Could some kind soul please tell me what the XeTeX equivalent
of PdfTeX's

	\immediate \pdfximage width 3 true in {Signature.png}
	\pdfrefximage \pdflastximage

would be, please ?

** Phil.