This task is not as easy as it may seem to you.
I suggest you have a look at docx4j or apache poi. I believe those libraries are capable of doing what you want.
It is not an easy task to convert the doc files to images using barebone programming. You might use some component for that matter. You may try Aspose.Words for Java. Aspose.Words for Java provides feature of converting doc files to images. This is a simple Jar having an easy to learn and implement API. Please see if this might help in your scenario.
Developer Evangelist @ Aspose. I love to explore and learn new technologies and help other developers along the way.
Can you really tell me that we aren't dealing with suspicious baked goods? And then there is this tiny ad: