Phd research in CS

Iam yet to register for phd..need to help to select the domain..

Iam BE in EEE and Mtech CS..with ..average fundamentals in both..However iam inclined
towards CS.. so i have glanced through IEEE papers in data mining, Bigdata, Deep learning,
and imageprocessing. More I go through , i get confused about the domain to be selected.
Image processing is interesting but highly mathematical..Deep learning was easy to understand.. as it dealt with neural networks..but my question is :is it outdated topic..or
what are the recent topics..in it ? similarly with Data mining and Big data .?
How should i go about it ?

I am a MS Mechanical Engg., so take my advice (if you can call it that) with caution. I have heard (through 'CS layman' channels) when I was in the university and even through peers that data mining and Image processing are always hot topics. I studied DSP in my Masters and found it deeply satisfying! Big Data seems to be a buzzword as well. But the best advice I can provide is to contact professors at the universities you have shortlisted and ask them about the research they do in their areas of interest. Make sure to tap on professors doing research in all the areas you are interested in. Why ask people who "might" have the correct information, tap the source instead! Best of luck and do keep us all updated.