No offense to the other people who answered, but their answers are incorrect.
1) You can definitely store images in a database, the data type is a Binary Large Object (BLOB), google it and you will find help in any RDBMS of your choice on how to implement.
2) The overhead of storing the BLOB in the database is often no more than storing it in the filesystem. A byte, is a byte is a byte. A database is only a mechanism to store data, but the data is not really any larger then if you stored the raw file.
There are always two ways to handle your problem. Storing on the filesystem has a couple of downsides. One of which is how to make sure the DB is in sync with the Filesystem. If a file were to be deleted from the Filesystem, and you tried to retrieve if from the db, you would have an error. Not catastrophic, just needs to be coded for. The alternate problem, is how do you clean up the Filesystem, when a file is removed and the DB column isn't updated.
Another set of issues is how do you manage security when you are using the DB for storing the image file name and the filesystem for storing.
On the other hand storing the BLOB in the database can be a little more difficult to code, and there might be issues around moving the images. Sometimes people want to store the images on the webserver or SAN for computer ops reasons.
For a simple DB/app, putting it in the db is perfectly ok.