[U-Boot-Users] Multi-Image File Creation

I think I've seen this question posted before but I haven't been able to find it.

Is there a way to extract the vmlinux.gz image from a U-Boot multi-image? I think it's something like this but I'm guessing I need the original vmlinux.gz size -

# strip the wrapper dd if=uImage.initrd bs=76 skip=1 of=uImage_initrd.stripped

# extract the gzipped kernel dd if=uImage_initrd.stripped of=vmlinux.gz bs=??? count=??? skip=???

Thanks in advance for any info.