Joining Beta testing here: https://play.google.com/apps/testing/com.redlee90.imagekitchenforandroid
DISCLAIMER: MAY NOT WORK WITH YOUR IMAGE. Due to the fragmentations among Android vendors, this app may or may not work with your boot image, and don't be frustrated when it does not. I am also not responsible for any damage to your phone.
BOOT/RECOVERY: Use this tool to unpack/repack a boot/recovery image. This part is built on top of osm0sis's Android image kitchen but added support for some MTK devices. You can use "dd" or apps such as "Flashify" to flash image back.
SYSTEM: Make sure you have root and a loop device enabled kernel to make the magic happen. If the system image is a sparse image, the app will try to convert it to a raw image in the same directory and then mount the raw image; if the system image is a raw image, the app will mount it directly. You can use "dd" to flash image back.
EDITING: You can edit plain text files with the built in file editor or your favorite file editors such as "QuickEdit" or "DroidEditor". You can also view images from the built in image viewer or other viewers. If you want to edit image or binary files, you need to first export the files out and edit them with other apps. "HexEditor" has a limitation which prevents my app from sending binaries for direct editing.
Shoot me an email at firstname.lastname@example.org for any bug reports or feature request. Please spare a second to rate the app and please DO CONSIDER donation if you love this app and want to support further development, Thanks!