If I put this tag in my HTML:

```
<img src="http://server/imageHandler.php?image=someImage.jpg" />

```

instead of 

```
<img src="http://server/images/someImage.jpg" />

```

and use the imageHandler.php script to read the image file, output expire headers and print the image data, i expect it to be slower. Is this a viable way to manipulate image headers or the performance penalty is too much since images are all around.
Are there other ways to set expire headers on images through my php code?