Dear Shanmuga,

I would suggest you visit the websites of journals that focus on publishing research papers in the field of Image Processing and download their recently published articles. By studying some these articles, I believe you would have some information about the state-of-the-heart research topics in Image Processing.

For instance, you can visit the site of the following journals:

1. IEEE transactions on Image Processing

2. IEEE Transactions on Multimedia

3. Computer Vision, IET

4. Journal of Graphics, Vision and Image Processing

5. Journal of Real-Time Image Processing

6. Signal & Image Processing 

Good luck

In addition to Williams comment, this document will help you to navigate the published work in an organized manner.