Subject: Get Info about XObjects images

Hello. How to get width and height of XObject images in mm or in user space
units? I have sizes of this images only in samples. Two metods:
page.getPageImages, than images.get(0).getWidth. Its will be in samples.
And page.getResources().getXObject()..getStream().getCOSObject().toString()
i will get sizes in samples when i parse it.