Matching patterns in a JPEG file

Hi!
Is there a way to match a definite pattern in a JPEG file given the original image and the image pattern to be matched. Also I would like to know whether there is a way to recognize the text in a image file?
Am I ambitious?

Yes, you are ambitious, but image processing and text recognition are possible in Java. However, you will have to deal with the pixels of a fully expanded image from the JPG. The compression in a JPG would make it very hard to find patterns.
The "Machine Learning / Artificial Intelligence" area that covers such tasks is HUGE. To get you started, here is a link to a recent survey:
http://www.developer.com/java/other/article.php/1559871
The following site has Java code
http://www.cs.waikato.ac.nz/~ml/weka/index.html
There are many many more, this is a very active area.
Bill

Thanks for those links Bill! Seems to be a big and time-eating task. If there are any implementation efforts already, that would be helpful
sudharsan