Hi Nithish,
I guess it's a good idea to read through the threads in this and other forums. You'll find a lot e.g. on image processing.
for "disk image" look e.g. at Wikipedia Disk image - Wikipedia, the free encyclopedia
Linux for embedded devices is pretty common. However, if you run only Arduino you probably won't care the underlying system anyways.
Why not start with https://software.intel.com/en-us/iot/getting-started?
Good luck and have fun