Expanding on Gist:5414535 this is a simple script to pull the kernels and ramdisks from a raw image with expected partitions.

rip_kernel_and_ramdisk_from_raw_img.sh

#!/usr/bin/env bash

# set -x
# DEBUG='echo'

device=$1
[ ! -f "${device}" ] && exit 1
output_dir=$( echo "${device}" | sed 's/.img//g' )
[ -d "${output_dir}" ] && exit 1
mkdir -p "${output_dir}"
start_block=$( parted ${device} unit b print | grep ' 1 ' | awk '{print $2}' | sed 's/B//g' )
${DEBUG} losetup /dev/loop0 "${device}" -o "${start_block}"
${DEBUG} mount /dev/loop0 /mnt
# ${DEBUG} file -s /dev/loop0
# ls /mnt
${DEBUG} cp /mnt/initr* /mnt/vmlinuz* "${output_dir}"/
${DEBUG} umount /mnt
${DEBUG} losetup -d /dev/loop0