yet another image: db or filesystem ? question

I've read the earlier threads on whether to store images in the database
or filesystem.  I think I understand the pros and cons of each method,
but I have a question on a specific use case.

Let's say I have a web app, and I want to display the images in a web page.

a) if the images are in the filesystem (and also under the web root), no
problem.  Just use <img src="filename.jpg" />

b) if the images are in the database...do I need to create a temporary
file first in order to use the <img> tag?  Or is there some other HTML
way of doing this?